Retrieving the synchronicity between people and water_Dhaka, Bangladesh by Sanjana Ahmed

source: author

etrieving the synchronicity between people and water

Colophon

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Title: Retrieving the synchronicity between people and water A spatial study of water resilient megacity, a sprawling unplanned urban tissue Dhaka

Sanjana Ahmed I sanjana.arch@gmail.com I Student number: 4504631

Mentor Team Han Meyer, Birgit Hausleitner, Exchange University (IUAV) examiner Paola Pelligrini External examiner Leo van den Burg External advisor Mahbubur R. Meenar Thesis report, February 2017 Faculty of Architecture and the Built Environment Delft University of Technology European Post- master in Urbanism (EMU) Studio: Frontiers

source: author

Content

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1_Introduction 1.1_Motivation

1.2_Framing the context

1.3_Problem field

1.4_Problem statement 1.5_Research questions 1.6_Relevance 2_Methodology 2.1_Aim 2.2_Research structure 2.3_Methods 3_Metropolitan Fabric 3.1_Analytic Framework 3.1.1_Form / Morphological structure I People Relevant cases

3.1.2_Centralities and activities

3.1.3_Water Dynamics Relevant cases 4_Project Structural Framework

5_Design development: territorial scale

6_Design development: local scale

7_Reflections

8_Bibliography

Acknowledgements I have been exceptionally fortunate to have two of my most favorite teachers as my thesis mentor, Han Meyer and Birgit Hausleitner, whom I admired from the beginning of my EMU studies not only as brilliant educators but mostly because of the way they constantly inspired me to enjoy such an intensive semester, not freaking out and still work on such a challenging site. My external advisor, Meenar Mahbubur, who willingly helped me all through with new ideas which really helped me looking at my project from a different perspective. My external mentor, Paola Pelligrini who sincerely helped her best despite of being in China. My friends and colleagues who have been working with me with the same tension and anxiety and making this final semester full of fun. Special thanks to my parents and my brother who have supported me with every decision I take, my boyfriend, Nayeem who has been a constant support and helped me with all the beautiful pictures that he has taken of Dhaka. All the people who have supported me gathering data and actually made it possible for me to work for Dhaka. Finally, I would like to thank the faculty itself for giving us the opportunity to be a part of such a program that allowed us travel a lot and learn things from people we met that we could have never learnt from the pages of any book. It has truly turned out to be an unexpectedly wonderful journey of experience in Delft.

fig: a

4 km

fig: b

4 km

All the drawings of this report is based on the two scales of the Metropolitan region of dhaka, fig: a; and the Dhaka city corporation area fig: b. The Metropolitan region incorporates the peripheral major towns and the Dhaka city corporation area is composed of two administrative parts. The North city corporation and the South city corporation under two different mayors.

1_Introduction ______________________________________________________________________________ 1.1_Motivation The city as a landscape of a set of natural and artificial structuring elements grows as an accumulation of these traces over time in shaping the territory in its bodily form as well as the behavior of its inhabitants. The construction of the territories of these urbanized landscapes in the urbanistic discourse finds its position in different typo-morphological categories which are often termed as sprawl, diffused, dispersed, isotropy or densified compact cities. The natural features, for example water and topography by setting the course and limit of the human occupation in the initial phase, often becomes the backdrop of some cities. Over densification or unplanned urbanization leaves very little room for a porous soft layer to be traced in a spread of continuous hard/asphalt urban tissue.Therefore,this very important structuring element, the water, becomes a challenge for urban environment when it comes to extreme events like heavy rainfall or flooding. The compact urban fabric doesnâ&#x20AC;&#x2122;t allow a porous surface for the water permeability that causes unprecendet flooding events. In the present world of liquid modernity where the future is more and more uncertain, (as discussed by Bauman, 2000) and where the trend clearly shows that territories are getting urbanized and people are inclined to be more and more urbanized/modernized every day (more than 50% of the world population lives in cities, U.N. 2007), the complexity of urban processes threatens the natural structuring elements (like the waterscape) of the territory ever more than any time before which naturally backfires in the long run.Therefore, in this project, my attempt is to examine this global challenge of urbanization process and its affects on the natural water system, in a very unique context of a city, Dhaka, where the city itself struggles with a lot of challenges like limitations of resources , climate change threats, economic challenges etc apart from the process of unplanned urbanization and its adverse effects on the water system. In the end, trying to find solutions or adapting principles of the western strategies of resilient metropolitan growth keeping an adaptable greenblue system in this particular context. 1.2_Framing the context General urbanization and the growth of Dhaka: The story of the city of Dhaka, the capital of Bangladesh which is 90% urban (Islam 2006), one of the worldâ&#x20AC;&#x2122;s most densely populated megacities with a population of 17 million, is a very similar prototype of a highly urbanized city that neglects the water system to find room for its growth, if seen from a morphological point of view. The city is geographically situated in the deltaic plain of three major rivers, Padma, Brahmaputra and Meghna, (see fig:1) and surrounded by the tributaries of these major rivers. Dhaka traces back its origin in the 17th century as a trading hub of the Mughals. Water playing the major role of transportation at that time period not only made it possible for the city to structure along the course of it but also in a way created the metaphorical image of the city. The limit of the city was clearly defined by the tributaries, Buriganga in the south, Turag in the north and west, and Balu in the east, and also the swampy lands all around the initial city clearly defined the urban-rural limit of the territory. (see Fig:2 & 3) The city underwent different phases of development where the pre-Mughal period was all about dispersed settlement spreading all around the territory. (see fig:2) The 16th century during the Mughal rule, the development followed the river Buriganga on the east-west axis. The big change was noticed during the British rule of the 17th century where the city started growing slowly towards the north because of the relocation of the industrial zone up north and the connection to that by railway line, at the same time, during the second half of the 17th century, the population started decreasing as well when Calcutta started getting more importance that Dhaka. After the liberation war of 1971, the city started growing in all its direction and the tradition of a centralized capital city with a concentration of all governmental and private development started from this time period. This tradition follows the trajectory till the present day and therefore, Dhaka faces such pressure of rural to urban migation pressure for all its valid reasons.

source: author

88E

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Dhaka

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Fig 1: Location of Dhaka in the context of the country: source: https://www.researchgate.net/publication/245189640_A_wind_map_of_Bangladesh

Legend

Pre Mughal period

Pre Mughal period Built up area 1750

miles

Built up area 1750

Pre Mughal settlement

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Legend Pre Mughal period

Pre Mughal period

Built up area 1850

Built up area 1950

Built up area 1750

Built up area 1850 Built up area 1750

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Built up area 1850

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Pre Mughal period

Built up area 2006

Built up area 1980

Built up area 1950

Pre Mughal period

Built up area 1850

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miles

Built up area 1980 Fig 2: Evolution of the urban area, Dhaka: source: author, based on Dhaka, An Urban Reader; Mahbubur Rahman

Built up area 2006

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1600

1750

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1960

1980

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Fig 3: Evolution of the river course, Buriganga, Dhaka: source: author, based on Dhaka, An Urban Reader, Mahbubur Rahman

1855

1905

1999

present Fig 3.1: Buriganga, Dhaka: source: http://www.bdchronicle.com/photo/detail/36, https://en.wikipedia.org/wiki/Buriganga_River

The pictures above show the conditions of the river course over different time period. The 19th century was all about the coexistence of the city and the river where the city development respected the river course and used it as the network of main transportation system. The river bank was found natural without much man-made interventions. After the severe flooding of the 1988, the riverbank was protected by dam construction which in the later phases caused dense urbanization process along the dam, keeping no room for river and with the development of all the other infrastructures, the water eventually became the backyard of the city. This process gave rise to a lot of negative Consequences both physical and metaphorical. As placed on the back side of all the development, people started perceiving the water as an element to neglect, pollute and encroaching its banks indiscriminately without any concern of the environmental effect on the overall landscape of the city.

However, this natural logic of rationality in structuring the territory today is totally ignored by the urbanization process. The phenomenon of rural-urban migration to the city made the city double in size from 1990 to 2005 and the U.N. predicts, by 2025, the population of Dhaka will be more than 20 million (see fig: 4.1) which is larger than Mexico City, Jakarta or Shanghai. All these extra amount of population is added everyday spatially in the low lying lands, by filling up the water retention basins, in some cases filling up the rivers in extreme, reclaiming river beds etc (see fig:5). As a result of such activities, frequent flooding events have increased in the last decade to a great number. The rivers that used to clearly define the limit of the urban-rural condition of the city, today is blurred and the city keeps on growing in all its directions in different morphlogical pattern keeping bare minimum porosity or fracture in the urban tissue. Therefore, a city once called the Venice of the east struggles relentlessly for the survival of its few remaining water courses and very often fails to withstand the brutal pressure of the tremendous urbanization process that completely ignores and mostly replaces the natural system of the city with complete asphalt surfaces.

To Mymensing

To Tangail

Gazipur area

To Narshingdi

Savar area

To Aricha

Kaliganj area

To Sylhet

Fringe area

Rupganj area Keraniganj area

To Mawa

Narayanganj area

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Existing dam To Chittagong

Existing roads Existing railway DMDP boundary Existing waterbody

To Munshiganj

Fig 4: Main rivers and roads, Dhaka: source: Dhaka Structure Plan 2016-2035

Legend

Value High: 15944

Low: 684

2.5

10 miles

Fig 5: Elevation map Dhaka:

Low lying areas specifically on the eastern part of the city is mostly getting urbanized filling up the marsh areas.

The core: The core of the city is composed of the similar kind of density in a very compact situation where the morphological study of the city following the space-matrix analysis shows very highly compact ground condition. The most common tendency is to build in smaller plots which has building regulations of 60% or higher maximum ground coverage laws for built structures that creats the very compact situation keeping very low ratio of open space on the ground in each plot. As a result of this kind of development, the city grows keeping insufficient porous space for water to recharge the ground. Dhaka aerial view: source_ http://www.skyscrapercity.com/showthread.php?t=407912&page=53

Growing street scape in compact condition: source_ https://www.eca-international.com/insights/blogs/march-2015/from-rickshaw-capital-to-elevated-capital-dhaka-t

Contrast between social groups: source_ dead poet photography

On the other hand, the core also faces the challenge of accommodating highly contrasting demographic group of people in the same areas . In one hand, the increasing number of high rise developments in comparatively smaller plots with expensive commercial uses , on the other hand informal settlements in an extremely compact condition creates the metaphorical image of the city which unfolds the story of high contrast in its spatial configuration. During 1985-1993, the volume of road traffic increased by 88 % whereas the volume of water and rail traffic declined in almost equal proportion. (the daily star)

The edge: The edge of the city which today is in constant pressure of getting occupied by the expansion of the core area is composed of a landscape which is under transition. Traditionally composed of smaller viallages surrounded by agricultural fields for mostly rice cultivation is today a place of transition that is losing its productivity due to lack of labour forces which is more and more inclined to migrate to the city on one hand, and on the other, invasion of the industrial sector on the outskirts of the city. Therefore, the landscape which was originally formed by the combination of riverscape and cultivated land with small village settlements are changing very fast its functional and visual character due to constant pressure of population from the core area.

Typical productive rural landscape of the outskirts of the city: source_ dead poet photography

The occupation of the river edge by brick fields and industrial activities, the highly dense new towns occupying the marsh lands on the edge of the city and the disappearance of the agricultural lands in order to accommodate new developments is the regular story of the edge of Dhaka today.

Brick field along water course on the periphery of Dhaka: source_ dead poet photography

Housing complex in the new areas: source_ http://dhakadailyphoto.blogspot.com/2007/08/blog-post.html

As mentioned in the draft, â&#x20AC;&#x153;The vision stands upon three pillars- Livability, Functionality and Resilience. It also has two conditions, a. respect towards a local socio-cultural fabric and b. environmental sustainability.â&#x20AC;?

Fig 6: Structure plan 2035, natural protected areas Dhaka: Dhaka Structure Plan Draft 2016-2035

The structure plan of 2035 is basically composed of three major layer which later subdevides in several sublayers. The urban promotion area occupies the layer of the city that will be considered for different kind of urban development with varying densities, the urban control area will be reclaimed as flood flow zones and other natural and environmental purposes and the existing and reclaimed water bodies to flow the water from the upstream to the downstream retention areas.

0.5

Fig 7: Map of existing water network and buildings, Dhaka

The above map shows the comparative proportion of the built and the unbuild surface of the city. The few fractures on the body of the city are basically airports, army occupied areas, parlament building areas owned and restricted by government, few parks, graveyard, national zoo etc.The small scattered water bodies are the most vulnerable ones that are getting filled up illegally every passing day.

1.3_Problem Field The impacts of extreme urbanization are severe in this particular case of Dhaka. On one hand, it faces extreme fast population growth, on the other hand severe flooding issues create challenges for current and future urbanization. The city as a system fails to accommodate and drain periodical rain water causing severe flooding issues (see fig: 5 & 6) more often these days. Rural to urban migration in the recent years and also in the projected future has been a challenge to manage due to several strategic decisions concerning the whole country. For example, lack of decentralization of economic, educational, productive and administrational sectors and concentrating everything in Dhaka. Therefore, people have no choice but to come to Dhaka for better livelihood and better opportunities.

Population Growth According to the draft of Dhaka Structure plan report 2016-2035, â&#x20AC;&#x153;63% of the total growth of Dhakaâ&#x20AC;&#x2122;s population is due to migration and only 37% growth comes from natural increase. From 1961 to 2001, in each of the four decades, about 73%, 77%, 73% and 57% respectively of the total growth of population have been due to in-migration.â&#x20AC;? Therefore, among uncountable number of problematic issues, the focus of the project will be to deal with this obvious pressure of inward migration in the local scale (see fig:7 & 13) and in a territorial scale work with strategies to reduce the pressure in the long term. On the other hand, reading the waterscape of the city, the synthetic relationship between this urbanization process and degradation of the water system will be the byproduct of this process of redistribution.

Fig 8: Total population up to 2010 from UN estimates. Notes: NI= Natural Increase; NI rates for both base population and migrants assumed as same, interpolated from UN national NI rates projection source: Dhaka Structure Plan Draft 2016-2035

Water Dynamics As mentioned before, the flooding issue mainly caused by the heavy rainfall coupled with peak river flow (see fig:10, 11) creates all the challenges in the urban areas related to water. The unplanned urbanization in the low lying marsh lands (see fig: 9), illegal occupation of river banks, insufficient sewage system etc add up to this challenge creating bigger risks for the future development. The challenge of the water system in such a context of highly dense urban areas are crutial. The population growth rate is much higher for the water (increasing flooding risk) to compete with. In the densly developed urban tissue, the rainwater runoffs never get enough space to permiare or flow safely towards the water storing areas, and therefore causes flooding in the urban areas.

Ledend

Fig 9: Slope map, Dhaka source: author

Legend 4 - 10

11 - 15

16 - 21

22 - 28

29 - 43

Fig 10: Contour map of Dhaka, Dhaka source: author

Legend

Existing dam Existing roads Existing railway Area under flood, 1998 Existing waterbody

Fig 11: Flood prone areas, Dhaka(1988): source: author, based on Dhaka, An Urban Reader, Mahbubur Rahman

Legend

Depression

Madhupur Clay

Floodplain

Abandoned Channel

High Floodplain

Fig 12: Types of soil, Dhaka: source: author, based on http://file.scirp.org/Html/5-9400102_1074.htm

The above map shows the soil composition of the city where almost the half of the city on the eastern side is composed of depressed marsh lands, flood plains having the Balu river as the edge. Interestingly, the abandoned channel very much unfolds the history of the disappearance of water bodies of the city where few lakes and cannals survived till the present day as a reminiscent of the past. The western part of the city with flood prone areas close to the river and the topographically depressed areas are also either already urbanized or under the pressure of the spill out effect of the city.

Fig 13: Types of soil,Dhaka and urbanization areas: source: https://www.researchgate.net/figure/293487877_fig3_Figure-8-Historical-changes-in-type-and-depth-of-water-wells-in-Dhaka-city

Legend

existing water bodies

lower flooding areas

higher flooding areas existing major sewerage system

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3 miles

Fig 14: 1998 flooding, Dhaka: source_ author based on https://www.slideshare.net/arjenzegwaard/proposal-dhaka-wotro2112012template

For a period of two months, the flood of the year 1998 lasted. Around 75% of the whole city was inundated. The reason of this flooding was heavy rainfall together with a combination of very high levels of water flows of all the three major rivers of the country in only three days time period. After this flooding,a lot of the low lying areas on the easter part of the city got developed as urban inhabitated areas which were marsh areas before.

Legend

existing water bodies

lower flooding areas

higher flooding areas existing major sewerage system

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3 miles

Fig 15: 2009 flooding, Dhaka: source_ author, based on, https://www.slideshare.net/arjenzegwaard/proposal-dhaka-wotro2112012template

An estimated highest railfall of 333mm in 24 hours between 27th-28th of July aggravated the flooding. In 2009, the maximum rainfall estimated during this time period was around 448mm in a day. Therefore, these maps (fig : 14 and 15) both shows the risk areas that are prone to flooding in case of severe rainfall.

1.4_Problem Statement Exhaustive densification due to inward migration in Dhaka city not only resulted in degradation of the spatial quality of the city, but also severely affected the water system. The quest of this urbanization process, without thinking about the quality of the land (either water retention basin or low lying marsh) grew like moss on all possibly available land over time leaving no room for water. Successive spatial development strategies have been initiated which lacks the strength of morphological richness to ensure fair livable conditions along with a holistic water resilient system. This opens up the opportunity to rethink how to accommodate the new inhabitants of the city in 2035 without disturbing the natural structural system of the city, needless to mention, the water.

Fig 16: Pictures of flooding, Dhaka: source: http://file.scirp.org/Html/5-9400102_1074.htm

1.5_Research Questions The idea of the project is to read the city as a palimpsest of different natural and manmade infrastructures over centuries and understand the dynamics behind the growth direction of the urban area and the spatial and functional effect on water of this urbanization process. The research questions to be answered during the study could be the following. What would be the spatial requirements to imagine a future of Dhaka city in 2035 where the structure of the cityscape allows to co-exist two liquid elements, an efficient water system and increasing demographic pressure? The sub questions as a supportive element of this question are,

1_Where and how will be the additional 11 million migrants accommodated in Dhaka city in 2035? 2_How can it be possible to ensure room for water in order to address the existing flooding issue when the population reaches 26 million? 3_How can the urban structure be adapted to mediate between the need to accommodate population growth and at the same time give room for water? 4_How is it possible to redefine the traditional way of practicing strategies in a territorial scale to reduce the inward migration process? 1.6_Relevance The issue of flooding in a mega city like Dhaka with an ever increasing population, has been a discourse in both governmental and societal level in the recent years through the media (see fig: 11). The evidence of its importance is clear in the recent initiative taken by the government, which is, â&#x20AC;&#x153;Dhaka Structure Planâ&#x20AC;?, 2016-2035, where significant spatial strategies have been thought out to re-organize the future growth develpoment pattern by identifying special zones for protecting and preserving natural areas both flood management and recreational purposes. Strategies for reclaiming the illegally occupied flood-flow zones in the city is one of those strategies (see fig: 12) to be implimented in the following years according to the draft report produced by the government, that is still under process.

source: author

Fig 17: Newspaper articles,flooding in Dhaka: source: http://www.thedailystar.net/news-detail-3883

Population 2035_ 3.91 M Gross density (PPA)_ 44 Gross urban density (PPA)_ 83

Population 2035_ 1.08 M Gross density (PPA)_ 20 Gross urban density (PPA)_ 36

Population 2035_ 3.44 M Gross density (PPA)_ 55 Gross urban density (PPA)_ 98

Population 2035_ 13.05 M Gross density (PPA)_ 176 Gross urban density (PPA)_ 202

Population 2035_ 1.31 M Gross density (PPA)_ 29 Gross urban density (PPA)_ 80

Population 2035_ 3.15 M Gross density (PPA)_ 59 Gross urban density (PPA)_ 112 Legend

Population 1991 Population 2001

Population 2011

Population 2015

Population 2020 Population 2025

Population 2030

Population 2035

Fig 18: Demographic projection, 2035 Dhaka: source: author, based on Dhaka Structure Plan Draft 2016-2035

The population increase of the city naturally does not distribute equally throughout the city. Rather it follows the tendency of major jump in the core area itself where the projection for the year of 2035 is 13.05 million. The pull factor of the major service and job sector concentrating in the core area is mainly causing this process. The north and north-western part of the city falls second in this position by having a projection of 3.91 and 3.44 million subsequently, which is a very minor number in comparison to the core area. The major recent development in these areas are growing industrial sector which also attracts a lot of industrial workers from all across the country.

2_Methodology ______________________________________________________________________________ 2.1_Aim The aim of the study is to develop strategies to address the obvious pressure of inward migration towards Dhaka city from the rest of the country and to reduce the environmental affects on the waterscape of the city due to this urbanization process. The symbiotic relationship between water as a structuring element of the territory and the pressure of urban growth on it will be the key focus of this project in a projected future scenario of 2035. 2.2_Research Structure

Metropolitan growth

Elaborate spatial analysis: morphological study

Relevance cases

Structure map

Fig 19: Methodology Chart, Source: author

2.3_Methods To answer the research questions identified in the initial phase, the following methods will be used to translate the research findings in the space to guide the design process in the later phases of the project. (see fig:19) 1_Where and how will be the additional 11 million migrants accommodated in Dhaka city in 2035? According to the population projection data for 2035, I will make possible structure plan showing the new density map of the future. To do this, I will study the spatial morphological analysis to understand potential locations of development and challenges. I will also analyze the FSI, GSI from the space matrix analysis to understand the urban tissue, integration of street network by spacesyntax, etc. 2_How can it be possible to ensure room for water in order to address the existing flooding issue when the population reaches 26 million? In this step, I would study the detailed topographic configuration of the territory in order to identify the water sensitive areas and create maps for locating future reserved areas for flood mitigation. Also, understand the dynamics of the water flow in the city and identify the hidden stream lines of the city to address the issue of flooding. 3_How can the urban structure be adapted to mediate between the need to accommodate population growth and at the same time give room for water? The findings from the spacematrix analysis will be combined with the spacesyntax integration maps and take precedence from relevance cases to find solutions. 4_How is it possible to redefine the traditional way of practicing strategies in a territorial scale to reduce the inward migration process? In this final phase, I will overlap the findings/maps of a. reserved areas for room for water and b. new density/ expansion areas for 2035 and try to set boundaries or limits to regulate illegal encroachment by developing a desirable scenario and also talk about guidelines/strategies for decentralization according to the findings of the first research question. Reflection Phase: _What are the major reasons of flooding and water logging in the city of Dhaka and how can they be addressed? In order to answer this question, I will re-evaluate the planning policies, strategies in a territorial scale and overlap the findings with my research colclusion and try to answer the critical questions and fill the mising gaps between the existing structure map of the city and the one generated in my design process. This will help me identifying the overall framework of the flood management system in a territorial scale. The latter would be to re-evaluate the smallest parcels of the city and adjust some changes in the building code regulation to ensure room for water in the smallest grains of the city. _How should the future expansion take place? Which elements should be the guiding principles of the new towns of Dhaka? I will make historical reviews and understand the archetype of the traditional urban environment of the city and list the major guiding principles to be followed in the future expansion process in order to contextualize the growth of the city.

source: author

3.1.1_Form / Morphological structure

3_Metropolitan Fabric ______________________________________________________________________________ 3.1_Analytic Framework

3.1.1_Form / Morphological structure

1600s_Mughal capital, city as the trading hub

1800s_British empire, industrial zone outside connected by railway

The city as a Mughal capital in the early 1600s was mainly a trading spot with a settlement of traders along the river Buriganga. The first major change of relocating the industrial zone on the northern side of the city in the mid 1800s by the British empire initiated the process of north wards expansion. The railway connection spreading from the south to the far north catered to this process of north wards expansion where the eastern side of the city was still unoccupied till the mid of the last century. 1900s_North wards expansion along the flood free areas

4 6

7 3 2

Fig 19: Morphological structure of Dhaka and locations of case study: source: author

The morphological structure of Dhaka speaks of the urbanization process itself. The southern part of the city which dated from the 1600s still has its very narrow organic web like street pattern with smaller plots. The buildings occupying the plots are changing with the present day need but the streets mostly remain the same. On the other hand, the upper northern and eastern new towns are typical example of grid-iron pattern as a method of fast and easy expansion, still having small plot sizes but this time wider streets than the old parts of the city. The morphological patterns other than these two typologies were either grown organically, owned by the cantonment, or built illegally, and later blended with the other parts of the city. The locations chosen for the Space-matrix analysis are based on different different morphological pattern and in some cases with different economic groups based on their geographical position in the city.

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1: Keraniganj

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Keraniganj shows very high GSI (ground space intensity) values with buildings ranging from one to six storey high in a fairly integrated street grid. The FSI (floor space intensity) values are relatively low in this particular area which creates the opportunity of future densification to meet the pressure of population increase.

2: Rayerbazar

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Rayerbazar shows lower GSI (ground space intensity) values with buildings ranging from three to ten storey high in a lower integrated street grid. The FSI (floor space intensity) values are relatively higher in this case which creates the opportunity of managing excess water on the ground level.

3: Lalmatia

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Lalmatia shows moderately high GSI (ground space intensity) values with buildings ranging from two to ten storey high in a moderately integrated street grid. The FSI (floor space intensity) values vary in this case from lower to higher which shows the character of the new developments that are taking place now a days.

4: Pirerbagh

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Pirerbagh shows lower to moderately high GSI (ground space intensity) values with buildings ranging from single to six storey high in a low integrated street grid. The FSI (floor space intensity) values are mostly low which also shows the possibility of future densification.

5: Mirpur

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Mirpur shows lower to moderately high GSI (ground space intensity) values with buildings ranging from three to ten storey high in a highly integrated street grid. The FSI (floor space intensity) values are on the higher end.

6: Gulshan 1

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Gulshan shows moderately high GSI (ground space intensity) values with buildings ranging from six to fifteen storey high in a highly integrated street grid. The FSI (floor space intensity) values are on the higher end. The OSR (open space ratio) which is also on the higher end of the graph suggests the potential of using the building volume for managing water since space is scarce on the ground level.

7: Rampura

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Rampura shows lower to moderately high GSI (ground space intensity) values with buildings ranging from two to nine storey high in a low integrated street grid. The FSI (floor space intensity) values are mostly low which also shows the possibility of future densification.

8: Uttara

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Uttara shows moderately high GSI (ground space intensity) values with buildings ranging from two to nine storey high in a highly integrated street grid. The FSI (floor space intensity) values are mostly on the mid to higher end which also shows the possibility of future densification.

9: Bangshal

0.0275

0.055

0.11 miles

The space-matrix analysis to understand the composition of built and unbuilt areas is done by taking plots as the smallest aggregation unit. The location of Bangshal shows moderately high GSI (ground space intensity) values with buildings ranging from two to six storey high in a low integrated street grid. The FSI (floor space intensity) values are mostly on the lower and higher end which also shows the character of this place that is in the transition of change.

2: Rayerbazar

3: Lalmatia

4: Pirerbagh

5: Mirpur

6: Gulshan 1

7: Rampura

8: Uttara

9: Bangshal

Theoretical background: Space, Density and Urban Form, Spacematrix_the spatial logic of urban density: Meta Berghauser Pont, Per Haupt The spacematrix analysis is very important for this project to understand the scale of density of the urban tissue. The readings of the floor space index (FSI), ground space index (GSI) along with the open space ratio (OSR) shows a picture of how dense the urban blocks are and what is the amount of pressure in the open space on those blocks. These readings allow me to categorize the blocks according to different qualities to densify in the future or restrict development in the future. It also helps to understand what kind of solutions is necessary for water management in different typologies of urban densities.

Fig 20: Spacematrix parametric model: source: Spacematrix, Meta Berghauser Pont, Per Haupt

Urban density calculation is a crucial parametric measure in the realm of urbanism which can be done efficiently by the method of Spacematrix. It is a multi-variable phenomenon to understand the correlation of density and urban form. Spacematrix follows the following parameters: Floor Space Index (FSI), Ground Space Index (GSI), and Network Density (N). These three measures are represented in a three-dimensional diagram, the Spacematrix. The Open Space Ratio (OSR), the average numbers of floors (L) and the size of urban blocks (w) can be understood from that (Berghauser Pont and Haupt, 2010). FSI on the y axis gives an impression of the intensity of the built environment of a particular area and GSI on the x axis shows the compactness or openness of that area. OSR represents the spaciousness or the pressure on the unbuilt area and the L subsequently represents the average number of floors. The calculation is done as following: for details see (Berghauser Pont and Haupt, 2010)

Fig 20.1: FSI and GSI combined reading of Dhaka: source: author

Fig 21:Existing green areas: source: author

Street network integration_Spacesyntax analysis The spacesyntax analysis is important in this project to understand which parts of the city are highly integrated and to understand the relationship between this level of integration with types of urban densities. This reading will later help me identify streets that are not globally and locally highly connected and which can be converted to water carrying structures to create an integrated water system. The color range from blue to orange indicates the level of street integration from lower to higher values.

Fig 22.1: Spacesyntax axial analysis r3: source_author

Fig 22.2: Spacesyntax axial analysis for global integration: source_author

The axial analysis in the global integration method identifies the major north-south corridors as highly integrated streets in the context of the whole city. The east-west connectors that are appearing highly integrated are the ones that is basically connecting the city to the major cities surrounding the city of Dhaka. Some of the areas closer to the highly integrated main streets also appear as moderately integrated which are postly laid out in grid-iron pattern.

Fig 22.3: Spacesyntax angular analysis for global integration: source_author

The segment analysis in the global integration method identifies the areas that are composed of highly integrated streets in the context of the whole city. It is interesting to notice that in this method the level of integrity is very high in most of the cases and few streets appear as low integrated which are located in under-developed areas in the periphery.

Fig 22.4: Spacesyntax axial analysis r3: source_author

Fig 22.5: Spacesyntax angular analysis rn: source_author

Fig 22.6: Spacesyntax angual analysis r3: souce_author

The angular analysis with a radious of 3 identifies the areas that are highly integrated in the local context of the city. The areas that appear as highly integrated are mostly the areas with streets laid out in grid-iron pattern and also the southern part of the old city where the streets are also following a certain grid for functional purposes. The areas that are composed of organic or tree like street structures are relatively low in integration level in this particular exercise.

Theoretical background_Streets and patterns_Stephen Marshal The reading of the different structures of street patterns help to understand the effect of different types of street patterns in urban areas in terms of their functionality. This reading later coupled with spacesyntax analysis provide rational background for proposing new development areas and thus their effects can be presumed.

Fig 23: The Modernist inversion of the relationship between urban movement and urban place; source: Streets and Patterns, Stephen Marshal 2005

Fig 24: Different typologies of street patterns of different time; source: Streets and Patterns, Stephen Marshal 2005

Fig 25: Different typologies of street patterns of different time; source: Streets and Patterns, Stephen Marshal 2005

According to Buchanan, the founding principle of Traffic in Towns is the distniction between roads for traffic and the roads providing access to buildings. In the words of Stephen Marshal (2005) in his book “Streets and Patterns” , “Formerly major streets became backwater access roads or pedestrian precincts. The most important traffic routes were no longer streets. The relationship between main routes and central places was reversed.The historic pattern of accessibility focused on the centres of settlements became replaced by accessibility distributed around the urban periphery. Whole settlements became, in the words of the writer Alex Marshall, ‘appendages off a freeway ramp’.11 At the scale of urban streets and blocks, modern road systems also turned pockets of the urban fabric ‘inside out’, inverting streetspace as the focus of public space.” The reversal of urban movement and urban place of activity made all the changes between the old morphological arrangements and the modernistic ones. 22

Fig 26: Adminidtrative boundaries, (ward);

The city of Dhaka is divided into different administrative areas named as Wards that are incorporated under the jurisdiction of Dhaka City Corporation which is responsible for managing the different affairs of the city. Each of these Wards are managed by a ward commissioner who works under the two mayor of the city from the North and the South city corporation. There are 36 wards in the North city Corporation and 57 in the South City Corporation.

Legend: Dhaka building count Bulding density 203-1462 1463-2920 2921-4445 4446-5913 5914-8480

0.75

Fig 27: Building density map based on adminidtrative boundaries, (ward);

1.5

3 miles

source:author

3.1.2_Centralities and activities

Fig 29: Density map: Amenity

0.75

1.5

3 miles

Fig 30: Service areas: Amenity clusters

0.75

1.5

3 miles

Fig 31: Density map: Craft

0.75

1.5

3 miles

Fig 32: Service areas: Craft clusters

0.75

1.5

3 miles

Fig 33: Service areas: Parks & Recreation clusters

0.75

1.5

3 miles

The cityâ&#x20AC;&#x2122;s green landscape is only a distant memory, with the more than 1,000 ponds, canals and parks replaced by houses, workplaces and markets for its more than 8 million people. (http://www.ipsnews.net/2000/08/ environment-bangladesh-saving-dhakas-remaining-green-charm/) It is said that only 5 % in old parts of Dhaka city and 12.5 % in new Dhaka is composed of green areas,â&#x20AC;? according to Azizul Huq, Chairman of the Dhaka Development Authority.

Population distribution

Legend: Dhaka population density

0.0-33519.6 33519.6-60663.2 60663.2-88184.1 88184.1-117040.8 117040.8-157671.8 0

Fig 34: Population density based on ward

0.75

1.5

3 miles

Fig 35: Apartment units increase trend,Dhaka: source: http://www.mdpi.com/2071-1050/8/2/119/htm

According to the study named, “The Contribution of Energy-Optimized Urban Planning to Efficient Resource Use–A Case Study on Residential Settlement Development in Dhaka City, Bangladesh”, “Dhaka city is facing acute housing demand due to continuous urbanization. As a result the housing business has grown progressively over the last 20 years. Since 2006, the main reasons for exponential growth of the real estate business are mostly related to land market issues, such as vacant land scarcity, higher land value, land speculation, and remittance inflow for land purchases. The increasing number of nuclear families and growing public confidence about living standards in apartment building also have played significant roles. Studies have estimated that the housing demand may persist or even rise in the coming years. For instance, by 2020 more than five million new residents need to be accommodated in Dhaka.”

3.1.3_Water Dynamics

source: author

3.1.3_Water Dynamics

75’

95’

90’

85’

80’

Pakistan China

30’

Nepal tra pu ma

Bhutan

er riv

ah Br

India Ganges ri

ver

Bangladesh

gna Meh

25’

r rive

Dhaka

India Myanmar

Ganges basin Brahmaputra basin Meghna basin Rivers

300 km

Bay of Bengal

20’

Fig 36: Watershed map

Dhaka, being 4m over sea level is one river basin which is located in the central position of the country where tongi canal is in the northern side, Turag-Buriganga river system on the west, Balu river on the east and Shitalakhya river on the south. Flooding in Dhaka is caused by either heavy rainfall in the city or by flooding from the surrounding rivers and canals. The western part which is densely developed is protected from river flooding by raised roads and an encircling embankment built after the 1988 flood. The eastern part of the city which is more vulnerable is expanding on low-lying floodplains that are submerged during the monsoon season. High rainfall coinciding with a high water level in the river, mainly floods the city since stormwater cannot be naturally drained through the water system. Flooding normally occurs during the monsoon season from June to September. The convectional rainfall of the monsoon is increased by relief rainfall caused by the meltwater of the Himalayas.

source: author

Permanent wetland 1978

Permanent wetland 1988

Wetland Loss 1978-2009

Fig 37: Permanent wetland loss map

The above diagrams show the loss of permanent wetland of the city over the last five decades. The major wetland area on the eastern part of the city mostly got occupied over the years by private developers which resulted in severe scarcity of exposed earth for water to permeate the ground. The shrinkage of wetlands caused severe flooding problems in the following years which in the present day is a problem for the whole city. Since the surface runoff cannot accumulate on the eastern lower side of the city, it causes high water clogging all around the city during major rain events.

Fig 38: City expansion along the water

Tongi canal

Turag river

Balu river

Dhaka Shitalakhya river

Buriganga river

Dhaleshwari river

Fig 39: The main water bodies surrounding the city

Even though the city is surrounded with rivers, the inner part of the city that used to have water channels connecting the rivers on both the sides have been occupied over time. The wetlands on the eastern part also shrunk with the increasing population. Therefore, there is not sufficient surface water corridors to channel the water from the inner part of the city to the downstream areas.

Fig 40: Annual rainfall data,Dhaka: source: https://www.worldweatheronline.com/dhaka-weather-averages/bd.aspx

Dhaka has a distinct monsoonal season, the annual average rainfall is more than 1248mm where nearly 80% of the annual average rainfall of 1,854 millimeters occurs during the monsoon season starting from May till the end of September. Wetlands and water bodies around Dhaka are being filled up by real estate developers to build high rise constructions causing severe floodig issues in the present days.(Climate_of_Dhaka: wikipedia)

YEAR 1956

RAINFALL (MM) About 326 mm

INCIDENT Recorded in 24 hours in Dhaka

1970

Category 3 typical cyclone

Killed 500,000 people

1989

Tornado

1991

Category 5 typical cyclone

2004

About 341 mm

Killed 1,300 people in Dhaka division Killed 138,866 people in the country Recorded in 24 hours in Dhaka

2009

About 333 mm

Recorded in 24 hours in Dhaka

Fig 41: Extreme weather data,Dhaka: source: https://en.wikipedia.org/wiki/Climate_of_Dhaka

During the beginning of July, because of heavy rainfall around the large parts of the Ganges, Brahmaputra and Meghna catchment areas severe flooding events occured accumulating over 300mm in less than 7 days. (https://www.ncbi. nlm.nih.gov/pmc/articles/PMC4344662/)

According to the report of “Trends in water level and flooding in Dhaka”, “We hypothesized that water levels have changed in frequency, magnitude and duration during the past century, and that mortality increases with or following extreme water levels. Our analysis suggests that water levels have indeed changed over the course of the past century. While the magnitude and duration of average flood events decreased, the frequency of extreme flood events has increased. Low water levels have also changed, with a significant decrease in the annual minimum water level most noticeable when we compare the time periods 1909–1939 and 1979–2009. A rise in mortality following extreme flood events could not be substantiated, but an increase in relative risk of death was found as water levels decrease.”

Fig 42: Ground water depletion,Dhaka: source: https://www.researchgate.net/figure/259923841_fig1_Groundwater-depletion-in-Dhaka-City-1

Water crisis image_source: https://freshclick.wordpress.com/2009/04/24/water-crisis-of-dhaka-bangladesh/

Dhaka being a megacity of 1425 sqkm achieves 75% of the total demand of water in which 87% is accumulated from ground water and the remaining 13% from different treatment plants. (https://www.researchgate.net/figure/259923841_fig1_ Groundwater-depletion-in-Dhaka-City-1).Therefore, the ground water level is going lower and lower every passing day.

Fig 43: Existing topography and water bodies_source: author

Fig 44: Sub catchment areas_source: author

Fig 45: Stream delineation_source: author

Stream delineation model helps to identify the hidden water network of the area based on the topographical configuration of the city. This alanysis will help me later in the proposal phase to identify the areas following these stream lines where the peripheral water network can be conected through the existing urban fabric in order to drain extra run off during the heavy rainfall of the monsoon period.

Fig: 46 Stream links delineation_source: author

Fig 47: Overlap of existing water bodies and delineated streams_source: author

Fig 47 shows the possible options for new blue corridors combining the existing water network and the delineated streams which together can work as a system of blue network that can drain extra run off in the case of heavy rainfall and thus reduce floodin in the existing urban areas.

Fig 48: Flow directions_source: author

Fig 48 shows the the flow directions of rain water on ground based on their elevation level. This map will help me identify the locations for water retention in up, mid and down stream to slow down the process of the natural drainage system.

Fig 49: Overlap of existing water bodies, sub basins and delineated streams_source: author

Fig 50: Topographical structure of Dhaka overlapped with hidden streams: source: author

Relevance Cases

The relevance case studies will help understanding different solutions for water management for different context. Room for the river project in the Netherlands is based on the goal to provide more room for high water levels of the rivers in more than 30 locations. The idea is to create socially inclusive initiatives in order to make these projects part of the urban realm. It is mentioned that, every river is unique and needs a tailor made solution. The basic principles used in these projects are following;

Fig 60: Room for the iver, principles: source: https://www.ruimtevoorderivier.nl/english/

Room for the river project: Nijmegen, Netherlands

Fig 61: The Dutch city of Nijmengen flood - control channel for the River Waal: source: http://citiscope.org/story/2015/dutch-city-makes-room-its-river-and-new-identity

Due to heavy rainfall in the upstreams in France and Germany, where the river is known as Rhine, severe flooding issues occurred in Nijmegen waal river basin. The project in Nijmegen is known as The room for the river, that takes into account not only flood protection measures, but also urban regeneration processes included in it. This particular case is relevant for my project because some parts of Dhaka has similar context with comparatively low dense areas on the upstream with flooding problem. The solution in such urban fabric could be similar to this solution.

Fig 62: The dikes are moved back and a new channel allows more water to flow: source: http://citiscope.org/story/2015/dutch-city-makes-room-its-river-and-new-identity

Flood management: The Soft Path New Orleans

Fig 63: The Soft Path, New Orleans: source: https://www.internationalrivers.org/flood-management-the-soft-path

The Greater New Orleans Urban Water Plan is a water-based landscape and urban design proposal that illustrates how the region can live with water rather than fight against it. (GNO urban water plan) The traditional practice of putting up a dam not only creates risks of failure and severe catastrophe, but also turns into serious land speculations. The soft path project of New Orleans, in the context of climate change, proposes a flexible solution to the ever changing flood risks. According to the description of the project, “Soft-path” flood risk management is flexible, in that it seeks to reduce damage to any size of flood, and adaptive in that it seeks to respond to the hydrological changes caused by changing land use and river morphology. Flood risk management assumes that floods will happen and that we need to learn to live with them as best we can, reducing their speed, size and duration where possible, doing our best to protect our most valuable assets, and get out of their destructive path. It assumes that all flood protection infrastructure can fail and that this failure must be planned for.” (https://www.internationalrivers.org/flood-management-the-soft-path) As mentioned in the project description of the GNO urban water plan report, “Building on existing infrastructure onestep at a time, the long-term vision of the Urban Water Plan is to increase water storage capacity by layering a system of waterways on street grids that supplements the current drainage system.” This is a similar case like Dhaka where the building of a dam not only increased the urban densification on the protected areas but also increased a lot of land speculation issues. The solution of this project could also be pertinent for the context of Dhaka in particular typologies of urban fabric.

Flood management, Dong Nai river basin: Ho Chi Minh City - Vietnam

Fig 64: Flood prone areas, Ho Chi Minh City: source: PBL projects

Lack of space and short-term thinking in the process of the development of the Ho Chi Minh city caused a large amount of development on dry riverbeds resulting in water drainage flooding. Another phenomenon is that, informal urbanisation is increasing within green infrastructures: the riverbeds and canals.The new highrise developments are draining the canals and building structures onto a thick foundation of sand, with not much room for water storage. An important city strategy is that of reconstruction of the canal system. Canals are being disconnected from the Saigon River by the placement of sluice gates. that prevent the tidal flows from reaching the urban areas, which thus become polders. As a compensation measure, the government is building a system of 103 water reservoirs; some of which are designed as park-like areas with open bodies of water. (Ton Dassen; PBL)

Fig 65: City Strategy, Ho Chi Minh City: source: PBL projects

The emerald necklace, Boston, massachusetts - USA

Fig 66: The emerald necklace project, Boston: source: http://www.sustainablecitiescollective.com/kaidbenfield/199141/bostons-emerald-necklace-sets-standard-linked-city-parks

The Emerald Necklace project is a 445 hectare chain park system encompassing waterways and fluvial parks designed by Frederick Law Olmstead. The idea was to clean up the marshy area. Olmstead proposed to include the Muddy river which flowed from Jamaica pond through the Fens to be included in the system by dedging the current into a winding stream and directed into the Charles river.

Fig 67: The emerald necklace project, Boston: source: http://blog.the-bac.edu/2015/04/in-background-back-bay-fens.html

Model of Metropolitan growth

Dhaka city for the future development in a metropolitan scale requires larger scale development aeas to accommodate additional population pressure. These model of metropolitan growth will help me propose models for satellite developments. Garden City Movement: Ebenezer Howard

Fig 68: Garden city diagrams: source: https://en.wikipedia.org/wiki/Garden_city_movement

The Garden city movement was initiated in the late 1900s by sir Ebenezer Howard to create self sufficient cities surrounded by garden belts containing proportionate amount of residential areas, industrial areas and agricultural areas. The vision followed the utopian ideas of garden city that would house 32,000 people on a site of 6,000 acres (2,400 ha), organized in a concentric pattern with a combination of open spaces, public parks and six radial boulevards, 120 ft (37 m) wide. The garden city when it will reach full population, another model garden city would be developed in appropriate site. Howard projected a future where a cluster of several garden cities would be built as satellites of a central city of 58,000 people, connected by road and rail. .

Fig 69: Garden city, Svit in Slovakia: source: https://en.wikipedia.org/wiki/Garden_city_ movement

Fig 70: Garden city, Zlin in Czech Republic: source: https://en.wikipedia.org/wiki/Garden_ city_movement

Chinese New Town model: Songjiang New Town

Fig 71: Chinese new town model: Songjiang new town, location, connectivity, axes, landuse: source: master thesis report_New Town Modeling_Yu Ye_Urbanism track_Delft University of Technlogy

Songjiang is a comparatively small city in the fringe of Shanghai that was planned to reduce the pressure of the central city of Shanghai in 1999. The planned followed a hierarchical model of a city with central core towards the service sector, nine new decentralized cities (300,000-1,000,000 residents), sixty small towns, and six hundred villages (2000 residents). This model of the city was called â&#x20AC;&#x153;one cityâ&#x20AC;? and it was built along the highway which later connected by a metro line to Shanghai city centre. In ten years, the city grew in an area of 22.4 sqkm with seven universities, central green belt and a financial centre . In order to attract people from Shanghai, the living quality of this new town not only provides apartment for middle class families, but also luxurious villas for the people of the higher economic end. The town has a model of several active node based development, to increase multifunctionality.

Fig 72: Chinese new town model: Multi node based model, aerial view: source: master thesis report_New Town Modeling_Yu Ye_Urbanism track_Delft University of Technlogy

4_Project Structural Framework ____________________________________________________________________________________ APPROPRIATE SOLUTIONS FOR WATER MANAGEMENT IN HIGHLY DENSED URBAN AREAS WITH VERY HIGH FSI VALUE AND VERY LOW GSI INDEX. STRATEGIES TO IDENTIFY AREAS OF GROUND WATER RECHARGE INTEGRATED WITH THE DESIGNED BLUEGREEN NETWORK. IDENTIFYING STREETS WITH LOW GLOBAL INTEGRATION VALUE AND TURNING THEM TO CARRYING STRUCTURES OF THE BLUEGREEN NETWORK. MULTI SCALER RAINWATER STORAGE AREAS TO SUPPLY WATER IN THE URBAN AREAS AND REDUCE PRESSURE ON THE GROUND WATER RESOURCE. DETENTION AREA IN THE DOWNSTREAM INTEGRATED WITH THE HIGHLY URBAN TISSUE. nEW SOLUTION FOR BUILDINGS IN THE DOWNSTREAM. USING THE LOSE URBAN TISSUE ON THE UPSTREAM TO CREATE BIGGER RETENTION AREAS AND PRESERVATION STRATEGIES BEFORE GETTING URBANIZED

Fig 73: Framework for design phase_source : author

____________________________________________________________________________________ DECENTRALIZATION OF CENTRALITY OF AMENITIES IN THE PERIPHERAL AREAS TO REDIRECT POPULATION PRESSURE FROM THE CORE AREAS. DENSIFICATION IN THE AREAS WITH LOW FSI INDEX AND DEVELOPMENT CONTROL IN THE AREAS WITH HIGH FSI INDEX. NEW SATELLITE TOWNS INTEGRATED WITH THE PROPOSED METRO LINE STOPAGES FOR ACCOMMODATING INCOMING RURAL MIGRANTS IN THE CITY. IDENTIFYING AREAS OF PRESERVATION TO RELOCATE URBAN OCCUPATIONS TO CONTINUE THE GAP BETWEEN THE BLUE NETWORK OF THE CITY. IDENTIFYING URBAN EXPANSION ZONES AND URBAN CONTROL ZONES BASED ON THE RISK FACTORS IDENTIFIED IN THE ANALYSIS PHASE. LONG TERM STRATEGY FOR DECENTRALIZATION ON A TERRITORIAL SCALE TO REDUCE PRESSURE IN THE CITY OF DHAKA.

possible blue-green network of the city

possible locations of new satellite development following major infrastructures

existing major sewage lines

existing water bodies and green

Fig 74: Multi scalar strategies_source : author

possible option for park system following ring road

satellite cities

The framework for the design development phase needs to follow the structure of a bilateral process that adresses two major concerns of the project, the water dynamics and the metropolitan structure in terms of building density or morphological characteristics. The two issues regarding water dynamics and morphological character need to follow the multi-scaler process of solutions at the same time. Starting from a structure in a territorial scale to guide the development of the future satellite towns to channel the natural water system of the whole territory. A combination of these elements can provide a direction and limitations for the future growth pattern of the city in a logical manner focusing nature as the main guiding and limiting factor.

option for blue network in highly densed areas and a system of green roofs using existing flat roofs

The structure of the territorial scale by setting its basic parameters for future development allows me then to delve further into the local scales that vary according to their geographical locations and morphological conditions.The basic issues of the project, the water dynamics and the morphological pattern unfold their possibilities differently in different sites in a local scale following the main structure of the territorial scale. The fractal quality of the water system and the urban growth pattern thus finds its trajectory in different scales following the same logic in each case. The basic principle of looking at the city as a body of layers starting from the natural to manmade, temporal and permanent can be noticed in the whole process of the design be it a territorial or a local scale.

possible densification/infill based on FSI-GSI reading

This project is therefore an attempt to set some principles as well as physical structural methods for the city that will allow the different stakeholders to follow a sructural background for the future development of the city. The policies and the structure map of the territorial scale will help protecting and limiting development in water sensitive areas , whereas the guidelines in the local scale will guide the developers to follow a new modular system for the newly developed areas in the fringes of the city which will generate a differen morphological pattern that can coherently accommodate water and people in harmony.

5_Design development: territorial scale ____________________________________________________________________________________

Fig 75: Existing water network, road network and urbaized areas

____________________________________________________________________________________

Fig 76: Proposed metro line and locations for satellite development by government_source: Dhaka structure plan draft 2016-2035

Fig 77: Overlap of delineated streams from DEM and existing water network

Fig 77 shows the exercise of the stream generation as an idea to identify the hidden stream lines of the city and find out the possibilities of re-surfacing them to mediate the shortage of surface water channels in the core of the city. On the other hand, to identify the hidden streams on the areas where there is a high probablity of future densification, and re-surface them before those particular locations get occupied by urban inhabitation and creates flooding problems like the core area today.

Fig 78: Proposed new water corridors_source: author

Fig 78 shows the water system as a combination of the existing ones and newly proposed corridors for the blur-green network of the city. The new water corridors while crossing the existing urban areas follow different logics to find its way through the highly densed areas, sometimes following the less integrated streets, sometimes channeling underground, sometimes incorporating existing smaller open water bodies to accommodate excess water in extreme cases.

Fig 79: New structure for urban growth (green-blue network) _ source: author

Fig 79 shows the proposed green-blue structure of the city where the green network that follows the water channels have multi-functionality. Sometimes in the case of overflow of water in heavy rainfall, it can work as fluvial park, agriculture land, energy park, meadow, in some aeas closer to urban areas it accommodates collective recreational activities in order to bring people closer to green, since the public green areas of the city is diminishing each passing day, (see fig 33).

Fig 80: Locations of proposed green-blue network on the topographical figure of the city _ source: author

The blue-green corridor not only allows managing the water system of the city, but also limits the development of these particular areas that are water sensitive to get developed illegally by allowing different programs along its trajecory which are mostly related to soft porous quality that can accommodate water and work as productive and recreational areas at the same time.

Fig 81: Suitability study of appropriate areas for water management projects _ source: Meenar Mahbubur

Fig 81 shows suitable locations for possible green stormwater management projects. This is a GIS based analysis that is done using different criterias to identify the structure of the blue-green network of the project. The criterias are following, _Elevation: areas with lower elevation are highly suitable _Waterways: areas closer to waterways are highly suitable _Rivers: areas closer to rivers are highly suitable _Hidden streams: areas closer to hidden streams are highly suitable _Parks and open spaces: areas within parks and open spaces are highly suitable .

Legend

proposed blue-green corridor existing water bodies existing urbanized areas proposed locations of new towns by the government proposed metro line by the government Fig 82: New structure for urban growth (green-blue network) developed by author, infrastructure proposed by the government and locations of new satellite cities proposed by the government _ source: author

Fig 83: Urban model precedence study: source_author

Fig 84: Urban model precedence study: source_athor

The urban model precedence study is used as a tool for the project to organize the configuration of the new town developments of Dhaka. The different urban model in this case unfolds some principles and situations that were developed in different socio-political settings with specific needs to be addressed. The study of these precedence models therefore illustrates some specific methods to be tested in Dhaka as well. For example, the Garden city model that is based upon logics of expansion to be organized among clusters of Garden town, village or cities among green buffer is a way to balance the proportion of inhabited and open space. This logic of organization is tested in Dhaka for accommodating the additional population of 2030 as a test case and the possibility and effectiveness of this case was later evaluated inthe case of Dhaka (see fig 85). This model was chosen based on the fact that Dhaka as a growing megapolis has the very tendency of sprawl that is posing threat to open green space as well as open water bodies as a reaction of the extreme need of expansion. Therefore, a structuring principle or logic is needed for the city in order to protect its remaining natural environment which is not only important for environmental causes but also for maintaining a better living conditions for the residents. On the other hand, the linear city model which is originally structured along linear configuration of infrastructure, in a setting of open green environment is also applied in the expansion scenario of Dhaka as a test case. Dhaka as a growing city of rural migrants faces the problem of informal settlement along most of the negative spaces of the city (see fig 84.1) that are either underused or work as a backyard of the city. For example, the waterbodies that are not put on the fore of the urban environment are the ideal situation for these kind of informal settlement to develop. Therefore, the linear city model is applied as an expansion model for Dhaka by putting the water corridors as the linear backbone along which the city can expand and making these corridors both physically and visually connected to people and finally bringing them to the fore of the urban environment to avoid these kind of spaces to be informally occupied. The finger plan of Copenhagen is also studied and tested in the case of Dhaka to find a logic of maintaining urban inhabited land and open space in a scenario where land is extremely scarce. The major challenge of Dhaka is the scarcity of land and the threat to the open spaces remaining around the city to be occupied very fast causing severe environmental issues such as flooding and heavy pollution. Therefore, the city needs to protect its open green spaces to function as a system where the future expansion does not pose threat to the natural layer of the city. The finger plan of Copenhagen is a logical case in such situation to be applied to maintain the open spaces in a structured way for the future expansion. Similarly, the case of Ranstad and Belgium is studied to understand the distribution of polycentric form of urban areas as well as the distribution of green space in such situation which is also relevant for Dhaka. Dhaka, as a home of 17 million inhabitants naturally formed the morphology of a polycentric city for simply functional reasons. The new expansion areas therefore also need to follow similar logics to sustain as a part of such system. The functional distribution of different programs and green spaces in the territory of Ranstad therefore is a precedence example for Dhaka that can be tested to redistribute programs in a way to promote decenrality. For example, in the new expansion areas, the new towns can house universities, hospitals, public administrative programs, IT clusters etc that are booming in the city which draw flux of urban inhabitants to concentrate in an area. These programs can be distributed in a balanced manner in all the new expansion areas to avoid over densification in the future. In the end, all these urban model as a precedence study feeds the project for a structure plan of Dhaka 2030, as a combination of tools and methods that can be applied and contextualized for achieving a balanced scheme of expansion in the future. The combination of different models and principles as required for the case of Dhaka is developed further in the structure plan proposed for 2030. (see fig 89)

Fig 84.1: Informal settlements of Dhaka : source_athor

satellite garden town

rin

agriculture buffer

TOD areas

blue-green corridor

metro line blue-green corridor

New satellite development _ Garden city model

New satellite development _ Transit oriented development

Fig 85: Possible structure map of Dhaka following different urban model precedence cases: source_athor

The figure showing satellite development following the Garden city model actually follows the basic principle of the garden cities as a concentric model of polycentric satellite system that in this particular case of Dhaka also takes into account the proposed green-blue structure of the city. This option of the structure plan brings the green corridor in the forefront and uses this corridor as a soft connection as well as a corridor that accommodates different programs which is always placed in the heart of each garden satellite city. On the other hand, the size of each garden satellite will be regulated to keep the agricultural land and the woodlands in between these areas which will help creating a balance between the proportion of the built and non built areas of the city.

The figure showing satellite developme velopment method is actually the metho city. In this particular case, he developm green-blue corridor and uses it as the ar velopment. The spaces in between eac ring roads will be again kept as agricult network in this case is the proposed rin proposed metro line running north-south

linear urban corridors

ng road

agriculture buffer agriculture buffer

blue-green corridor

metro line

ent following the transit oriented deod that is most naturally seen in the ment takes into account the proposed reas to be preserved in the future dech urban corridor following the major tural land and woodland. The transit ng roads by the government and the h through the existing fabric.

New satellite development _ Linear development (filament)

The figure showing satellite development following the Linear development model focuses on the strip like development along the proposed blue-green network where this soft path is always the center of he urban corridors where all the amenities and public programs are placed along the water course. This is a strategy to bring back the use and metaphor of the water like the historical times and not let it to be treated as a garbage disposal backyard element which is neglected and exploited most of the time, rather, this option helps to bring the image of the water in the city of Dhaka in the psyche of the people as an element to appreciate and enjoy in their daily lives which has been changed over the years of unplanned growth.

Fig 86: overlap of stream delineation, urban fabric and existing water network: source_author

Legend proposed fluvial park existing water bodies re-surfaced water corridors proposed underground water channels Fig 88: growth structure to be followed for future development: source_author

Legend agricultural land proposed fluvial park existing water bodies re-surfaced water corridors proposed underground water channels proposed roads Fig 89: Proposed structure map for Dhaka, 2030: source_athor

existing road network

proposed roads in new expansion areas

existing water bodies

proposed water corridors

existing green

proposed green network

Fig 89.1: comparison between existing and proposed layers of the Proposed structure map for Dhaka, 2030: source_athor

public transportation axis underground canals retention areas

storage areas

ultra dense urban environment

existing city

1_Major public transportation connector

2_water system

existing village settlements agricultural field proposed water corridor

blue-green network

4_Existing landscape qualities of expansion areas

Fig 89.2: diagrams showing different elements of Proposed structure map for Dhaka, 2030: source_athor

main water corridor

new linear expansion areas along water corridors

proposed water corridors

multifunctional hubs

agricultural buffer area

3_Future expansion areas

proposed roads preserving existing village settlements

new urban expansion areas

agricultural fields

room for water

5_New configuration of infrastructures preserving existing landscape elements

Fig 89.2: Proposed strategic zones for Dhaka Metropolitan Region, 2030: source_Dhaka structure plan 2016-2035

Fig 89.3: Proposed flood flow zones for Dhaka Metropolitan Region,

The proposal from the government for the structure plan of Dhaka cosists of different ideas of managing future population growth a as well as the proposed ring roads to serve the flow of traffic outside the core area. This scheme is taken into consideration in the he government for flood flow zones along the main rivers. This proposal of the flood flow zones of Dhaka in my project have been of the city. Fig 89.4 basically shows the proposal from the government for a park system to improve the quality of urban environm city which works as a metropolitan park in the territorial scale and then breaks itself into different scale parks for neighborhoods, b is therefore not only for environmental purposes, but rather it serves as a place where everyday life of the city can take place in d all kind of morphological configuration of the city, starting from the edge of the city to the hyper dense core areas to the water fron

2030: source_Dhaka structure plan 2016-2035

Fig 89.4: Proposed green netwok for Dhaka Metropolitan Region, 2030: source_Dhaka structure plan 2016-2035

and flood management possibilities. Fig 89.2 shows the proposals for different strategic zones with different density of programs e project since the construction of these bypass roads are already under construction. Fig 89.3 mainly shows the proposal from n evolved based on the analysis of the water dynamics that identified the major problems and possibilities of the water structure ment in the city. This proposal of the park system in my project is actually incorporated with the main green-blue network of the blocks and individual houses and works as a multi-functional system of parks for the whole city. The idea of a park in the project different manner. The flexibility of this park system therefore houses different productive and recreational programs that reaches nt and so on.

agricultural land wetand landfill sites urban areas future urban expansion areas waterbody

urban expansion 1960

1980

1990

2002

2016

2030 gro

2002

2016

2030 gro

water body, wetland, agricultural land 1960

1980

1990

Fig 89.5: Evolution of urban areas, water network and productive green areas Dhaka, 2030: source_athor

owth scenario based on tendency of expansion

2030 growth scenario based on proposed blue-green network

owth scenario based on tendency of expansion

2030 growth scenario based on proposed blue-green network

Fig 89.6: Estimation of the number people in the future satellite developments of Dhaka, 2030: source_athor

Site area: 51 sqkm = 51,000,000 sqm Considering minimum 30% of the site is constructed as infrastructure, Buildable land area = 15,300,000 sqm As the maximum ground coverage according to the analysis is considered 50%, therefore, Built up area = 7,650,000 sqm Number of people that can be accommodated in each level = 4,25,000 person considering 18 sqm area is needer per person in a housing development (BNBC, page:63, chart:1) Therefore, if the number of floors are 6, then the number of people that can be accommodated on this site = 2,550,000

The total number of people that can be accommodated in all the satellite cities is = 12, 750,000

6_Design development: local scale ______________________________________________________________________________

The study of the transect is basically an exercise to examine the different morphological character of the proposed structure plan. The proposal consists of linear configuration of new towns along the proposed blue-green corridors which are located around the periphery of the city. These locations for new towns/ future expansion sites are identified on the higher topographic locations of the city and at the same time adjacent to the re-surfaced water corridors. The idea of these new towns is to bring water in the center of the development to bring it back to physical and metaphorical life of the city. After crossing the periphery of the new towns, the transect looks into the existing core area where the idea is to mainly recycle the low integrated streets into water corridors to channel the water inside the city. Finding the porous layer of this existing fabric to show new possibilities or scenarios of densification was another intention of studying the existing urban fabric of the city. The Western edge of the transect is kind of a repetition of the Eastern new town typology but slightly different based on their gro-morphological character. To explain the design proposals in each of these typologies, several locations are chosen on the transect to study further in detail and propose site specific solutions for water management projects and possiblities for densification for the future. Each of these projects even though different in their functionality and scale, is actually part of the structure plan which as a system works as a common platform for water and people. Based on their geographical location in the city and their relationship to their surrounding, these projects aim to house the fluid character of water and population in the coming years as the city on one hand needs to expand and on the other, needs to accomodate water and increasing population in a coherent manner.

new satellite town

agricultural field

Road layer

Water layer

zoom 3_w water front qulity of th water and relation

Green layer Fig 90: Transect area for zoom in study: source_athor

new satellite town

blue-green corridor fluvial park

western zoom 2_high dense t showing urban areas with very little porous he edge, d urban surface; mostly covered with asphalt. nship.

zoom 4_dense urban areas with potential of new densification.

zoom 1_fringe area showing new satellite development and inbetween villages and towns amidst agricultural fields.

6_Design development: local scale ____________________________________________________________________________________ The satellite development of this particular location follows the local condition of the lanscape keeping the existing village settlements in between their course of development. The blue-green network in these particular areas work as a connector between the village like character of the fringe areas as well as the new urban areas in the satellite towns.

The proposed metro line by the government on the eastern side of the city runs in the north-south direction which also creates possibility for the eastern part of the city to get developed in the future. However, the eastern side is mostly composed of low lying marsh lands (see fig: 80) which poses a threat of flooding in these areas. Therefore, the new satellite developments on the eastern side of the city are proposed in a manner that only allows development in the areas that are safe for urban development, and at the same time limitig the growth of the low lying areas by occupying them with the proposed blue-green corridor.

The fringe areas in between the inner city and the propsed satellite towns basically consist of filament like urban corridors following the main infrastructures and agricultural fields where small homesteads are configured as villages loosely spread out along the territory. These fringe areas, in the proposed structure map for Dhaka 2030 is kept as it is by maintaining its character as a buffer between the inner city and the proposed saellite areas which are connected by public transportation routes and major infrastructure corridors.

Fig 91: Zoom 1_Axonometric view of fringe area and proposed new urban area: source_athor

____________________________________________________________________________________

4 1

multifunctional hub_ metro stop, local commercial activities

agricultural fields of the local villagers

agro tourism_ interactive farming activities for residents and tourists

retention area

fluvial park

recreational park

preserving local landscape elements and village settlements.

rural areas

The street pattern of this new settlement is derrived from the co ural landscape of the site. The areas that are developed as urb are used as small agricultural fields and the green pockets consis village settlements are kept as it is by restricting main infrastruct tions so that the new urban areas cannot expand after a certai regulations in the structure map.

new urban areas

The urban fringe areas with filament like develop ricultural fields are kept as it is in the proposal an dense inner city and newly proposed moderately

new urban areas Fig 92: Zoom in study: source_athor

onfiguration of the natban are the areas that sting dense green and ture and utility connecin limit which is set by

proposed metro stop with mixed used programs

pment and villages surrounded by agnd used as a transition between hyper densed satellite towns.

urban fringe areas as buffer

Fig 93: Perspective view showing proposed green-blue corridor conditions in low water level: source_athor

The above illustration portrays the image of a city where the transition from a hyper dense inner city to new satellite towns are s very flat inhabited landscape where the main occupation of the inhabitants is farming. These areas are protected in the proposa of the city toa certain extent. The fresh produces of these areas are usually transported to Dhaka and therefore, these areas a main city, the fringe areas and the new satellite towns that are seen as a background of the image and allows recreational slow fields in the dry seasons.

series of agriculture fields, pasture lands and traditional village settlements that are commonly seen in the outskirts of Dhaka, a al not only in terms of environmental implications but also they are identified as productive landscape that ensures food security are very important to be protected in the future. The proposed blue-green corridor in a way works as a connection between the w movement of people and allows water to flow downstream in case of extreme rainfall or can be merged with the agricultural

Fig 93.1: Perspective view showing proposed green-blue corridor conditions in high water level: source_athor

Plot size: 134 sqm Road width: 6 m FAR: 3.15 MGC: 67.5 %

Plot size: 335 sqm Road width: 6 m FAR: 3.75 MGC: 60.0 %

Plot size: 804 sqm Road width: 9 m FAR: 4.75 MGC: 55.0 %

Plot size: 1206 sqm Road width: 9 m FAR: 5.25 MGC: 50.0 %

Fig 94: Visualizing different options of building code application based on Bangladesh National Building Code regulations: source_athor

Fig 95: Bangladesh National Building Code regulations for different types of residential development: source_BNBC guide

Storage area: 10% of the site area for surplus of rainwater run-off

Site area: 11 acre

MGC: 50%

Fig 96: Application of selected BNBC regulation on the proposed new blocks of the satellite developments: source_athor

Fig 97: Peak flow calculation method _ source: ftp://ftp.odot.state.or.us/techserv/Geo-Environmental/Hydraulics/Hydraulics%20Manual/Chapter_07/Chapter_07_appendix_F/CHAPTER_07_appendix_F.pdf

The storage capacity, (peak flow rate of run off) for the retention scheme/reservoirs calculated in a typical block as shown in the diagram for the newly developed areas based on the parameters (specific building code, specific MGC, in a return period of 10 years) is, 159402.9 ft3/s The sum of the different areas of different materials of this block is, 220282.979 m2 Total amount of water falling in two hours for this block is, 6608.478 mm Water flow calculation formula: (0,03-(depression storage *0,001)-(2*infiltration loss*0,001))*surface Total surplus of rainwater run-off in this block is, 1709.875 m2 when there is open water you can store 0,5 m3 per m2, therefore, the area required for surplus water storage in this particular block of 11 acre is, 3419.75 m2 which is 10% of the block.

Main infrastructure provided

Main water infrastructure provided

Fig 98: Model of public and private development strategies in each block for the new satellite areas: source_athor

Fig 94 shows different existing options of plot development in Dhaka where the majority of the residential areas have smaller plot sizes like the first two options of the image. The maximum ground coverage (MGC) of the built surface decreases as the plot size grows larger which means the ration of open green or porous space also increases as the block size increases, (see fig 95). Therefore, in the case of the new satellite towns, the proposal for the minimum block size is 1206 sqm. Fig 96 illustrates the quality of a typical block in the proposed satellite town where the MGC is 50% . The rainwaterrun-off calculation following the peak flow calculation method (see fig 97) shows that a minimum of 10% storage space is needed for surplus run-off in such block size. Therefore, the policy for these satellite towns will be regulated in a way that allows 50% MGC and a 10% of water storage area for each block. The overall impact on the open porous green surface of the city in this way will be very different from the inner city. The smaller plot sizes in the inner city with unusable ratio of green fragments which are often insufficient to infiltrate water can be altered by changing the block sizes and overall impact of this if seen in a accumulative manner is going to be a very possitive one. Fig 98 shows the main infrastructures that will be provided by the government and the inner storage areas need to be maintained by the inhabitants of each block.

4 5 1 2

Fig 99: Axonometric view showing new satellite areas with the fluvial park: source_athor

The idea of the new towns is mainly to re-create the traditional neighborhood type dwelling clusters facing the water to re-connect the physical and metaphorical relationship between people and water. The neighborhood scale clusters follow the block based development system (see fig 96) that allows maximum 50% ground coverage for the built structures and 10% water storage areas to be kept inside the blocks for extra rain water run off as a mandatory rule. The overall idea of facing all the newly constructed structures facing the water corridor close to the main backbone is actually helping the water edge to protect from informal type illegal settlements and unwanted pollution of the waterbody. One of the major reasons behind the illegal encroachment and pollution of the water edges is putting the water on the backside of buildings which is altered in this case. The network of water squares, rain gardens, bio-swales etc connects to the main blue-green corridor which is then connected to the major water corridors of the city. The main commercial activities are clustered along the most integrated streets and are facing the water. The inner courts transform themselves to water squares for surplus rain water run offs and the intermediate spaces in between the blocks are used as urban farming areas that are maintained by the local community members.

1 main blue green corridor

rain water storage space for block

2 urban farming

network of bioswales along roads

3 existing rural settlements

block based superblock development instead of typical plot based apartments

Fig 99.1: Standards for future land development: source_Dhaka structure plan 2016-2035

Fig 99.2: Standards for future housing development: source_Dhaka structure plan 2016-2035

Fig 99.3: Standards for future neighborhood development: source_Dhaka structure plan 2016-2035

Metro stop

Fig 100: Zoom 2_Axonometric view of existing urban areas highlighting elements to be addressed in design: source_athor

lin

Fig 101: Existing FSI - GSI condition of the area: source_athor

Major

axis

Fig 102: Existing road integration of the area: source_athor

ajo

xis

Fig 103: Proposed blue corridors following less integrated streets in highly densed areas : source_athor

Fig 104: Condition of the blue-green network in monsoon with high level of water: source_athor

The above image shows the condition of the network in monsoon when the water level is high and the low integrated streets that are converted to blue-green corridor are filled with water in extreme case and the pockets of green areas along their way are used for smaller retention areas. (see fig 106)

Fig 105: Condition of the blue-green network withthout high level of water: source_athor

The above image shows the condition of the network in dry seasons when the network is used as green public space in hyper dense city. These corridors in this case provides new green areas in locations where such space like recreational park or green is really scarce or a luxary. (see fig 107)

Fig 106: Perspective view showing condition of the blue-green network (low integrated street in highly dense urban environment converted to blue-green corridor) in monsoon with high level of wate

er: source_athor

Fig 107: Perspective view showing condition of the blue-green network (low integrated street in highly dense urban environment converted to blue-green corridor) without high level of water: sou

urce_athor

Edge quality: _illegal settlements along the edge of water. _mostly informal settlements along the river. _road parallel to the river in poor condition. _upper northern part of the road parallel to the river constructed as a dyke. _water quality is highly polluted with domestic waste product. _mostly lower elevation therefore flooding occurs in high level of water from the river. _water on this side of the city is mainly used for transportational purposes for the people living on the other side of the river. _the first layer of the built structures along the road mainly accommodates mixed used type programs like small local shops, kitchen market etc on the lower levels and residential facilities on the upper. _local boat stops with low frequency of water transportation. _demographic distribution is mainly middle and lower middle income group. _no proper recreational space or the water is in no way used or designed as a recreational element of the fabric. _the visual connection from the urban to the waterfront is mostly blocked by informal settlements.

Fig 108: Zoom 3_Water front area on the north of Buriganga river: source_athor

Fig 109: Perspective view showing the existing condition of the water front: source_athor

_informal settlement along the water edge

_new construction of residential uses

_small local shops on the ground levels

_illegal reclamation by filling up with sand

_local street quality

6 5

1 3

Fig 110: Proposed interventions on the water front: source_athor

1 room for the river

temporary fish selling stalls

2 water treatment plant

local boat stop

3 waterfront cafe

local boat stop

The proposal for the water front provides room for the river since the over flow of the river in this part of the city is seen in case of extreme rainfall. The road parallel to the water is constructed as a dyke which is already existing on the upper north of the city but absent in this part, whereas this part needs the same treatment which has not been done yet. The waterfront will increase the quality of public space in this area and can be used as a model for the water front of the southern and eastern part of the city.

2 3

Fig 111: zoom_4, Existing urban area,(Uttara; sector 8) identifying potential sites for future development: source_athor

The North-western part of the city, a densely built residential area, Uttara is a typical example of the residential zones of Dhaka which is comparatively new and still under development. The independent residential buildings owned by single steakholders that were built around the early 90s which are mostly 3/4 storeys high, are getting redeveloped by private builders in the context of recent booming real estate market. Fig 111 identifies these type of independent housings as well as vacant sites of this particular area as porous layer that has the high potential to be developed as high rise apartment buildings as a profitable investment of these land owners. Even though highly profitable for the real estate developers and the landowners, these kind of gated individal apartment building construction has a strong collective impact in the social landscape of the city. The traditional neighborhoods which used to have a strong sense of community is geting totally lost with the construction of these kinds of gated individual apartments. With the pressure of increasing housing need in the city, it is more and more likely that all the porous sites of the city will eventually be developed as such gated apartment buildings keeping very little or no physical or social connection to its surroundings. 2/3 storey buildings as potential

1 spaces for future densification

3 existing school area

2 vacant plots

4 existing water body

The graph shows the morphological character of this area where there is a clear distinction between the new and old buildings. The new apartments show higher FSI and GSI values which means both taller buildings and compact ground condition and which are mostly along the highly integrated streets.

Legend high value of street integration low value of street integration building location in FSI/GSI graph

The typical plot sizes of this area ranges from around 134 to 335 sqm. The building code allows construction of residential buildings with a maximum ground coverage (MGC) of 67.5% to 60% subsequently, with a floor to area ratio (FAR) of 3.15 to 3.75. The result of such code is very little open space for water to penetrate the ground in individual plots, which is most of the time not sufficient for rain water run off management system. The overall impact on the whole area of such smaller plots with high MGC values increases the amount of asphalt surface in the city that needs further attention of adjustments to increase green surface either on the ground or within the buildings.

Plot size: 134 sqm Road width: 6 m FAR: 3.15 MGC: 67.5 %

Plot size: 335 sqm Road width: 6 m FAR: 3.75 MGC: 60.0 %

To manage rain water run off within the individual plots in the context of climate change where the problem of flooding is increasing every monsoon, it is high time that the environmental factor should be integrated as a mandatory factor within the building code regulation.

Another element surrounding the plots are the boundary walls constructed with brick or concrete, usually 2 to 3 meter high, not only create a physical barrier, but also make it less transparent. As a result, most of the time, the open space on the ground that should be kept green is paved illegally keeping no room for water to penetrate the ground. Therefore, the building regulation should be altered to restrict construction of such hard barrier, rather ensure creating natural boundary with vegetation that will allow visual transparency and at the same time preserve privacy.

(a)

Original regulation: Plot size: 420 sqm Road width: 6 m FAR: 3.75 MGC: 60 %

(b)

Original regulation: Plot size: 1206 sqm Road width: 9 m FAR: 5.25 MGC: 50.0 %

Proposed regulation: Plot size: 420 sqm Road width: 6 m FAR: 3.75 MGC: 40 %

Fig 112: Proposals for individual plots for future development based on the size of each parcel; (a) single parcel, (b) combination of two or more parcels, (c) incorporating green surace within the buildings: source

Fig 112 illustrates the different options of future development possibilities based on the proposed building code regulation. The p for rain water to permeate the ground. On the other hand, if different stakeholders and land owners combine their plots and con open green space for rain water management projects, but also can provide effective usable green spaces for multipurpose use (c)

Original regulation: Plot size: 420 sqm Road width: 6 m FAR: 3.75 MGC: 60 %

Proposed regulation: Plot size: 420 sqm Road width: 6 m FAR: 3.75 MGC: 60 % Green surface within the building: 10%

The other option for future construct code regulation. The additional adju the ground level (see fig 96). The gr size for extra rain water run off man adjustment proposed here is the dem

Original regulation: Plot size: 1980sqm Road width: 12 m FAR: 5.50 MGC: 50.0 %

Proposed regulation: Plot size: 1980sqm Road width: 8 m FAR: 5.50 MGC: 55.0 %

e_athor

parcels that are less than 420 sqm with a MGC of 60% is reduced to 40% to ensue bigger open green space on the ground level nstruct in bigger parcels, they get higher MGC which will be up to 55%. This kind of parcel clustering will not only ensure more es like children play area and so on in a city where green parks are very rare and deminishing every day.

tion is keeping the 60% maximum ground coverage for the individual parcels that are less than 420 sqm as it is in the building ustment in this case would be adding a 10% of the total floor area of the building to be kept as green to substitute the green on reening of the roof is a mandatory for such kind of development. The 10% open space is a mandatory requirement for any plot nagement project in each parcel based on the calculation done following the rational method as illustrated in fig 96. The other molition of hard boundary walls and creating green screens for privacy purpose. 71

In the recent years the attempt by the notable architects of the country has been to incorporate green within the building in an extensive manner as well as finding the cultural roots in the archetypal expression of the buildings. The use of traditional material like locally made brick and re-introducing courtyard spaces within the building have been the major elements that are coming back in the architecture of the recent years.

Apartment building, Architect_Marina Tabassum, (MTA) , source_ https://www.pinterest.com/pin/548524429588176094/

Following the current building code regulations, which allows up to 60% of maximum ground coverage (MGC) or in some cases more than that for the building itself, these kind of courtyard and smaller semi public green spaces indise the plot have been impossible to propose by the architects since the owner of the plot would insist to have the maximum built up volume in their property. Therefore, the bigger plots that have a different regulation than the smaller plots allow the architects to incorporate green spaces within their site and thus bring back the traditional courtyards in the living environment. These traditional courtyards were used in the past not only as an extension of indoor space but also they had functional environmental purposes for example cooling of the interior spaces by ventilation the hotter air through these voids of the courtyards sorrounded by building masses. These self shaded courtyards by building masses would then allow semi private activities for the residents to be carried out which included play area for kids, teenagers or even meeting points for everyone on special occasions.

Apartment building, DOMUS architects , source_ http://www.skyscrapercity.com/showthread.php?t=241806&page=38

Apartment building, Shatotto rchitecture , source_ http://worldarchitecture.org/architecture-projects/pgmh/gulfeshan_apartment_building-project-pages.html

On the other hand, the typical residential apartment buildings by most of the regular real estate developers is actually a physcal manifestation of only using the building code regulation to its maximum limit. These kind of buildings occupy the maximum limit of the building code which is most of the time the demand of the client and does not have any kind of physical or visual relation to its surrounding. The open green space within the plots of these kind of apartments are not sufficient for draining extra rain water on site let alone open space for recreational purposes for the residents. The flexibility of changing the spaces of the residents or the owners residing in these kind of buildings are rather rigid. The exterior envelope should be kept intact according to the design of the developer, whereas only the interior spaces can be re-organized if required .

Apartment building , source_ http://www.skyscrapercity.com/showthread.php?t=420728&page=23

Since land value in the city of Dhaka is increasing every passing year, these kind of residential buildings are also sprawling and are the ones that are demanded the most by clients to make the full use of the land they own since they are post profitable ones. Therefore, if the regulation is altered to promote building in bigger plots and lower the percentage of the maximum buildable limits on the existing smaller plots, the overall impact on the living conditions will be a lot different than today and it will also bring environmental changes for example reducing heat of the micro-climate, ground water recharge rate etc. Most importantly, in a fast growing hyper dense city where recreational green spaces like parks are extremely scarce, these small pockets of green usable spaces can bring a change in the living conditions of the city.

Apartment building , source_ http://www.skyscrapercity.com/showthread.php?t=420728&page=23

Apartment building , source_ http://www.skyscrapercity.com/showthread.php?t=1562596&page=58

Fig 113: Future development scenario with multiple options based on the new building rules: source_athor

The idea behind the densification of the existing urban areas is ensuring construction in bigger plots in this particular case combining vacant plots that are adjacent to each other or recycling old buildings that will eventually be demolished and converted to high-rise apartment buildings. The advantage of combining plots is having more open space on the ground floor following the building code regulation (bigger plots having more open space and lesser maximum ground coverage of built structure) which will allow to provide green spaces for recreational purposes as well as for water management projects. The single plots can be developed following the existing bulding code regulation but adding 10% of green area within the building volume based on the calculation done following the rational method for excess rain water run off management. The connected system of bioswales along the sidewalks will work as a carrying structure of the surface run offs to drain the water to the main blue-green structure of the city. local commercial development on individual plot

Super blocks based on new building code ensuring bigger open space for water management project, community spaces within the building or at the ground level Demolishing barrier of boundary walls

School area, Open space infront of school for mustipurpose use, local water retention area as well as play area

Parking structure with 60% MGC to meet the need of parking spaces in these areas

Syatem of bioswales draining rain water run off from the streets to the water bodies.

Fig 114: Local water management system and new building typologies following proposed building rules: source_athor

Each of these new super blocks needs to provide 30% of its volume for accomodating housing for lower income groups to ensure social mix in these areas. Green roofs in these kind of dense urban environment will help achieving more green surface in the city where having open green is not possible on the ground level. Each of these super blocks will ensure mix of social groups as well as mix of programs by having not only residential uses but also providing recreational and local commercial uses on the lower levels. This mix of uses will help to ensure a transparent and interactive relation with their surrounding.

1 3

The new urban infills

10% open green space for excess rain water run off

30% subsidised social housing provision for social mix

ground floor for parking space and first floor for collective amenities

local commercial space

mandatory green roof in all new super block developments

multi layer parking space

Fig 115: Aerial view of local water management system and new building typologies following proposed building rules: source_athor

1 multifunctional open space for water and activities

4 side walks

2 system of connected bioswales along sidewalks

5 school playground as retention space and play area

3 main blue-green corridor

6 rain garden

4 6 5

8 9

Fig 116: Aerial view of new development areas following proposed building rules: source_athor

Fig 117: Aerial view of new development areas following proposed building rules: source_athor

blue-green 1 main corridor

existing dense urban environment

existing agricultural land

10 airport

2 hospital

transition/buffer protected area proposed water corridor

11 railway

3 secondary water

proposed metro line by govt. bigger blocks close to main corridor

corridors

12 proposed 30% land area with basic infrastructure for informal settlers

The idea of the new expansion areas of dhaka in a linear configuration along the blue-green corridor is a way to revive the neighborhood character of the traditional settlements of the city. In the wake of the market driven economy in the last decade, the new individualistic apartment construction without any relation to their surrounding, has been a common practice all around the city. This expansion model is therefore a way to retrive the sense of community that used to have in the traditional neighborhoods (mohollas), where people share open common public and semi public spaces incorporated inside each neighborhood. Another important regulation for the construction of these kind of super-blocks in the new expansion areas is to add 30% of subsidised social housing in each residential unit to ensure the possible mix of different social groups in each block. The buildings close to the blue green corridor gets more Maximum ground coverage to build on their site where as the buildings farther from the blue-green corridor get less maximum ground coverage to construct within their site boundary. This process allows the stakeholders of the buildings that are close to the blue-green corridor to invest their share of water-management investments on the corridor itself making it possible to finance the whole blue-green structure of the city. The more construction is carried out along the main corridor, the more investment can be acquired from these stakeholders. On the other hand, the plots that are further from the main corridor should follow the building code regulations recomended for the new towns or incorporate the required amount of green within the building volume. Each of these blocks therefore is composed of different social groups since 30% of these buildings are built as subsiised social housing to ensure different economic groups co-residing in the whole area. Another measure to be carried out in the expansion areas of Dhaka is to allocate 30% of the overall land as flexible area with basic infrastructure provided for informal settlers to settle for a certain period of time. This way of allocating land can help to protect the water edges from getting illegally occupied by informal settlers. On the other hand, this area can be used for future development/expansion with the increasing number of people coming to the city every day.

rain water harvsting system

Small scale water management projects at the building level feeds the block and from the block, this water is drained to the main blue-green corridor with the bioswales that are integrated with the sidewalks of each block. The proposed block level development instead of plot level development as a whole provides a different physical environment for the collective life of the residents where these different scaler green areas can accomodate people and the uncertainity of the water level rise when needed.

30% subsidised social housing

bioswale

preservation of local greenary

basic infrastructure (columns, sewage) provided

ground water recharging system

10% of the block (based on rational method) open for water management pro

community space community space

30% land for informal settlers

30% subsidised social housing

Fig 118: Section of new development areas following proposed building rules: source_athor

geound floor and first floor open for parking and amenities 10% green area incorporated inside the building

cistern

green roof

bioswale

oject, (extra rain water runoff)

30% subsidised social housing

community space

room for water

Main blue-green corridor

agricultural land

proposed water corridor

Fig 1119: Aerial view main blue-green corridor: source_athor

proposed n

fluvial park

building closer to the blue-green corridor having higher cistern MGC

neighborhoods

inner shared courtyard

room for expansion

protecting existing villages

proposed roads

building further from the bluegreen corridor having lower MGC

7_Reflections ______________________________________________________________________________ As mentioned in chapter_2 at the Methodology section of the paper, the idea was to reflect upon the following questions,

_What are the major reasons of flooding and water logging in the city of Dhaka and how can they be addressed? _How should the future expansion take place? Which elements should be the guiding principles of the new towns of Dhaka?

To answer these questions, the project initiates to attempt a design research perspective on the traditional scheme of planning and designing methods. Throughout the process, the idea was to first look at the territory as a palimpsest of layers starting from the subsoil through the topography and all the man-made and natural layers on top of them over time. The idea of time works here as a variable that suggests clue for the future proposals to be contextualized and grounded to the roots. The major reasons of flooding and water logging of the city, as unfolded through my research process are loss of wetlands mainly on the eastern side of the city which causes water logging issues all around the city in the monsoon period when there is a combination of heavy rainfall and high level of river. Another rather implicit reason is actually the morphological character of the city that is getting more and more profit oriented due to the extremely high value of land price. Each of the parcels of the city is built to its maximum limit, which needs immediate attention in order to increase the ratio of open space in the city through its smallest parcels. If not, the overall impact will never be positive in environmental aspect, livabality context or recreational purposes. The main dichotomy of the conflicting issue of inward migration in Dhaka and its effect on the water system causing serious flooding problems is addressed in all the scales. From the territorial expansion to the new development areas to the existing hyper dense inner city, it illustrates different methods that can be applied in different context of these locations. All these methods and possible solutions connect to the main backbone of the territory and spreads all around in different scales as a fractal system. The multi scalar approach of the project is equally important in this case as it not only provides a structure map as a backbone, but also zooms in a way to set limitations for the fine grain module of the urban fabric. To be particular in this case, the practice of Dhaka is to build in smaller plot sizes whereas this project sets guidelines for the new expansion areas to build blocks as the smallest module of the urban fabric as the smallest gain and creating neighborhoods as clusters as an intermediate scale. The building codes and guidelines are taken from the existing building code regulation of the city, but rather fixed by choosing certain limits to provide actual usable room for water management in each block. The project does not negate the proposals and guidelines generated by the government, rather it sheds a critical reflection on taking them to one step farther. It address the issues found in the analysis phase for example the analysis of the territory from the perspective of the layer approach, historical analysis and precedence study comparison, morphological study, hydrological study etc and thus updates and proposes a new adaptive structure for the territory that can work as a backbone of Dhaka for expanding in the future years to come. Therefore, in a nutshell, it is an attempt to take the proposals of the government as a starting point and contextualizing it on the aspect of flexibility to accommodate environmental and demographical pressure for the future. The traditional way of living in urban neighborhoods where the sense of community was strongly evident in their physical urban spaces that used to house local market place, play areas, courtyards etc are totally lost in he present day Dhaka. The new areas are mostly monofunctional, for example zoning based development strategies like residential areas, commercial areas, administrative areas etc which have shaped the city in the last five to six decades are actually very different from the traditional way of promoting multi-functionality which is still found in the old part of the city. Therefore, the idea of the future expansion areas of the project is to promote new regulations for building to ensure neighborhood kind of development and bringing water to the fore again. The major guiding principles of this project in the case of future expansion are addressing the environmental challenges as the first step, in this particular case make room to let it flood and then reviving the traditional way of living in the city by promoting clusters of neighborhood with a social mix. The way of clusturing the neighborhoods not only provides a new way of urban living, but also provides room for water in the smallest parcels of the city. In short, by creating an adaptable structure for the territory and setting some principles for accommodating nature and people coherently in the city, the project opens up whole new array of design research possibilities in all different scales respecting the main structure of the city in the future days to come.

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