The Ordinary Nature of Landscape Design by Mengting Ren

The Ordinary Nature of Landscape Design for Flood: —— researching a series of drainage pattern to minimize waterlogging problems

MENGTING REN s3664991

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Water storage devices

pemerable street

Water storage devices on the roof garden

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pemerable street

vegetation for rain garden

ABSTRACT

Title : The Nature of Landscape Design for Flood

When floods occur in densely populated areas, human beings have to face some significant threats in the destruction of property and threaten human life. Beyond that, there are more people who have to endure the homelessness, frustration and destruction left behind after the flood. With climate change and urban development over the past few years, cities are being flooded with increasing frequency, which means the situation will worsen in the future. This visual essay list a series of methods which be used in urban design, in order to improve the drainage system of the city. Using green spaces, permeable material and green roofs to control flood which flows into public spaces, streets and buildings. In addition, these approaches guide urban planners to explore more suitable methods that controlling flood flow and achieving the goal of water resources recycling.

Author : MENGTING REN Student number : s3664991 Publication date : 2019 Publisher Studio Ltd. The Studio Publications

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Lineage Lineage Map Map of of Flood Flood Management Management

THEORY

THEORY

River flowsRiver are flows are important in important drainage.in drainage.

The properties The of properties of soil influences The interaction of The interaction ofsoil influences drainage design floods withfloods plantswith plantsdrainage design

Storage andStorage utilize and water utilize water

Rain Garden Rain Control Garden Control Water Pollution Water Pollution

Use of the Use intensity-duration of the intensity-duration urban SustainableSustainable urban formula to formula determine to the determine peak the peak drainage systems drainage systems flow rate needed flow rate to design neededato design a culvert culvert WaterCity Sensitive City Water Sensitive

KEY THINKERS

KEY THINKERS

INSTITUTIONS

INSTITUTIONS

Wetlands and Wetlands and SustainableSustainable Development Development

Froehlich, Froehlich, David C. David C.

Watabe Saburo, Watabe et Saburo, al. et al.

Billow, Lisa Billow, Lisa Ellis J.

A new permeable A new permeable pavement material pavement material

Bentarzi, Y,Bentarzi, et al. Y, et al.

Briony C. Ferguson Briony C. Ferguson

Ellis J.

Gary Austin Gary Austin

J.J. Rothwell J.J. Rothwell

Kongjian Yu Kongjian Yu

Kongjian Yu Kongjian Yu

TT KOZLOWSKI TT KOZLOWSKI Van De VenVan F.H.M., De Ven F.H.M., Nelen A.J.M., Nelen A.J.M., Geldof G.D. Geldof G.D. University University of of ManchesterManchester

DepartmentDepartment of of Forestry, University Forestry, University of Wisconsin, of Wisconsin, Madison, Wisconsin Madison, Wisconsin

Sponge citySponge city

The National ofInstitute of TheInstitute National Applied Sciences Applied(INSA) Sciences (INSA)

Monash Water Monash Water for Liveability for Liveability

Ph.D., D.WRE, Ph.D.,P.E., D.WRE, P.E., M.ASCE M.ASCE

Founder ofFounder Turenscape of Turenscape

Founder ofFounder of TurenscapeTurenscape

PROJECTS

PROJECTS

Qunli Stormwater Park Park evaluate the evaluate hydrodynamic the hydrodynamic Qunli Stormwater behaviour under behaviour real high under real high rainfall conditions. rainfall conditions.

Rain garden needed at home Rain garden needed at home Be designed Beand designed and maintainedmaintained

METHODS

METHODS

VegetationVegetation

Soil water Soil movement water movement

Rainwater Rainwater storage device storage device

Green roofGreen roof

Pemerable Pemerable street street

Drainage design Drainage design

water permeable water permeable material material Combine Sewer Combine Overflow Sewer Overflow

Establishing Establishing ecological ecological infrastructure infrastructure

Strategy goals Strategy and planning goals and planning processes processes

Wetlands Wetlands

19801980

20002000

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20102010

20152015

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1. INTRODUCTION Land and water are among the most widely used natural resources. Due to various natural and man-made factors, the contradiction between land and water is gradually revealed. Land not only can landfill and absorb water but also can be submerged in water. When the amount of water exceeds the capacity of the land, flooding problems will follow.

The most notable phenomenon is that sea level rise and fierce floods have swallowed up the land. When floods occur in densely populated areas, damaging property even threatening human life, human beings have to face and endure the homelessness, frustration and destruction left behind by floods. In recent years, with climate change and urban development, cities have been flooded with increasing frequency, which means that the situation will worsen in the future. How to deal with the flooding problems that may be encountered in the future will become a hot issue in the field of urban planners and environmental protection.

During the flooding, Melbourne's central business district, which includes Elizabeth street and Flinders street, and large areas of surrounding suburbs, such as Kensington and North Melbourne, were particularly dangerous areas where multiple floods occurred (news.com.au 2017). Victoria has suffered multiple floods of varying sizes during this period of 1863 to 2016, according to Andrew, B.(2017),75mm of rain hit Melbourne and flooded Elizabeth Street in a short period of time in 1973.

In recent years, with rising sea levels, unpredictable weather and unusual terrain, Melbourne has faced an unpredictable flood crisis.

It is necessary to use special viewing methods to guide or analyze the urban rainwater information, so as to build or start to construct a more perfect drainage system to solve the flood problem in the future.

The urban water network is affected by topography so that there are

Fig.1: Photographer Neville Bowler took an iconic photo of the Melbourne floods at the scene. The photo illustrates traffic zones was swamped in the Elizabeth street around the Melbourne central station, and cars went over the roof in the flood. Pedestrians were stranded on benches as water roars down Elizabeth Street during floods.

varies in the infiltration capacity of rainwater in different areas. Most cities did not take drainage seriously when they were first planned, and it was not until the surrounding depressions and marshes were regularly covered by rain that they began to face flooding. However, with a well-planned drainage system, the interior and surrounding villages will minimize the problem of flood erosion (Abubakar et al., 2012).

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2. ANALYSIS CONDITIONS OF FLOOD

This visual essay about developing a new way of viewing, aim to use a form of digital information ranging, from publicly accessible data through GIS and sensors to analyze the trend of Melbourne floods and try to find a reasonable drainage way to reduce the harm of floods to Melbourne. In order to achieve this goal, trying to collect the following digital information for urban flooding analysis and exploration.

Fig. 2: The photo was taken in the city of Melbourne, Elizabeth Street, where is the main road to connect commercial, university and residential centres. Rainwater pouring into Elizabeth street - along the main drainage channel that turns Melbourne's streets into canals. As the flood is raging everywhere, the residents continue to live in the water or trapped in the high-rise buildings, which has seriously damaged their lives.

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2.1 The former lakes and wetlands

2.2 Land use Fig. 4: Block for census of land use and employment. Digital information obtained using GIS Data on Census of Land Use and Employment Block (CLUE) in Melbourne, including commercial areas, green spaces and floor

Fig.3 This data delineates historic water bodies including wetlands, the ancient Yarra River and Moonee Ponds Creek alignments and lakes (presumably seasonal and generally estuarine). The location of former rivers and lakes that have been buried or submerged, can be used as a reference to find suitable catchments because of the special soil and biological structure of these places. A large number of seeds were found in former lake sediments, and the depth of existence is significantly different between different lakes, which is explained as the remains of the early vegetation stages (Skoglund and Hytteborn 1990). Therefore, the remains of former lakes and wetlands are in a good position to develop new water storage areas, because the presence of organisms can purify rainwater. Looking for the location of the former rivers and wetlands as a clue to predict where the flood will occur. These areas still have special soil and biological structures after being filled or submerged. At the same time, these areas can be considered within the scope of the catchment area when planning the urban drainage network.

space, provides an overview of the regional resident distribution structure. The spatial layer shows the location of the Land Use and Employment Census (CLUE) boundary and the employment, location and floor area of each block in 2016 (City Of Melbourne, 2019). The utilization of the land is illustrated by stratification of five different employment Numbers. Most of the places with the least employment are residential areas, and most of the places with the most employment are business centres or factories. This map provides information about which areas are densely populated and which are crowded areas. This helps to select the right drainage direction to divert the flood to the place where the crowd is sparse, avoiding large-scale life safety problems and property loss problems because the crowded area is often the place where the buildings and infrastructure are relatively perfect. During extreme flood events, important information about the type of underwater land use and land cover is quickly identified by the extended flood area, which can be used to carry out comprehensive relief efforts (Chau et al., 2013).

By understanding the land use of a city, including the distribution of commercial areas, residential areas, campus areas, green spaces and wetlands, it forms a conceptual framework that drains and surface runoff. In other words, when a flood occurs, the first place to be rescued is the public space area, because these places gather too many citizens and infrastructure. In order to prevent the occurrence of tragedy and the loss of public property, the flood problem in these places should be dealt with in the first place. On the contrary, the flood should be discharged away from the public space, looking for rivers or catchments close to the suburbs, in order to relieve the flooding pressure in the city centre first.

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2.3 Water flow routes 2.4 Existing urban drainage conditions Fig.5: These flow routes are derived from the 2008 DEM surface using ESRI Spatial Analyst stream order tool with STRAHLER ordering (City Of Melbourne, 2019). This GIS map shows the different level of water flow routes over the land in Melbourne. In urban flooding, rainwater runoff is the main reason causing flooding as well as one of the main methods to control urban flooding. The data of water flow routes over land show the flow direction and concentration area of stormwater. With the characteristics of the terrain, rainwater accumulates in low-lying areas to form flood peaks, due to the hardness and impermeability of the ground. This can block traffic and affect people's lives. This GIS map selecting five different runoff volumes shows that even with the same amount of rainfall, topographic features make runoff different from place to place. Areas with high runoff are prone to flooding because the surrounding runoff collects and ends up in low-lying areas. Many urban plans use this information to divert rainwater with garbage and pollutants into nearby streams or rivers to mitigate the effects of flooding on the city. The water flow routes reveal the direction of the temporary rainstorm flow, helps to predict the location of the catchment area so that the population and property can be transferred in advance, and also helps to select the appropriate drainage route to divert floods in the Melbourne central. Urban

Fig.6: Drainpipes map illustrates different diameters of drainage pipes, showing the underground network of drainage infrastructure(City Of Melbourne, 2019). Existing drainage systems are only adequate to handle domestic water and trace amounts of rainfall. However, heavy rains can cause drainage networks to collapse, further contribute to the process of flooding due to blocked or damaged drains. Flooding in catchment areas is usually caused by heavy rainfall in a short period of time and these catchments have the highest runoff. Clearly, figure 6 shows that where population and construction are dense, the denser the drainage pipes are. When the amount of rainwater exceeds the capacity of the underground drainage pipe, flooding will occur. Therefore, when solving the flood problem, we must first clear the blocked underground drainage pipe network, so that the city can return to normal order.

planners need to change the direction and size of stormwater runoff when managing floods. Artificial terrain and filling or digging can be used to transform the drainage system network based on the original overland urban water flow routes.

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Fig.7: Stormwater pits map with different colours for grate width. It states that most wider pits built at around central of commercial and residential areas. A large number of pits have been built along the Yarra River or other creeks to help drain rainwater from the city and further avoid casualties and damage to public property.

These visual data helps to develop more appropriate drainage methods in urban planning. The underground drainage network and stormwater pits complementing each other, help to deeply understand the whole drainage

2.5 Where does the flood comes from and flows to?

system throughout the city or region and also improve to research the amount and flow direction of underground rainwater. When stormwater flows into the underground drainage network, a large amount of rainwater cannot be discharged beyond the capacity of the drainage, which forms a flood. Floods are usually caused by insufficient drainage systems in and around the area, and heavy rains occur in a short period of time. When the rain is too much, the surface runoff will be stagnant for a period of time, which is the result of floods (cited in Abubakar et al., 2012).

This article introduces three aspects to control flood: where does the water come from, where does the water flow to and what is the water absorbed. Stormwater is a direct cause for a flood with climate change because flooding almost rarely happens in where low rainfall. It is necessary to develop and improve the drainage system to minimize stormwater damage. Flooding or waterlogging affected by stormwater and domestic water, especially for stormwater which flows into green spaces, buildings and streets. It can make the same effect when domestic water exceeds the capacity of the drain. The biggest problem of flooding in the city is that there exists an inadequate drainage system. Firstly, rainwater that falls on the buildings flows into the underground drainage pipes along with domestic water when the storm hits. A portion of street rainwater also flows into underground drains along with surface runoff. A part of the water goes into green spaces and is absorbed by plants or diverted into rivers, which followed by topography. Urban flooding occurs when rainfall far exceeds the rate of drainage. When stormwater flows into the underground drainage network, a large amount of rainwater cannot be discharged beyond the capacity of the drainage, which forms a flood. Floods are usually caused by insufficient drainage systems in and around the area, and heavy rains occur in a short period of time. When the rain is too much, the surface runoff will be stagnant for a period of time, which is the result of floods (cited in Abubakar et al., 2012).

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3.1 Green roofs and walls

3. DISCUSSION OF METHODS The Melbourne city provides a good communicative environment for residential, commercial and educational activities. The infrastructure required for these activities includes buildings, green Spaces and public places, enriching people's lives. The flood mitigation plan describes ways to ensure the quantity and quality of public and private infrastructure in urban planning. For short term goals, using a series of methods to deal with the problem of domestic drainage and to ensure the normal operation of infrastructure. There are four permeable types to meet the needs of different roads. For long term goals, parks and gardens perform many functions, including collecting, cleansing, and storing stormwater, and recharging underground aquifersďźŒin order to achieve recycling of rainwater. Potentially stormwater contributes to an environmental amenity in the city. In terms of the building where collected water, using green roof and wall to absorb a portion of rainwater. One part of the water was evaporated or drained into the streets. As for streets, using permeable material and drainage pipes absorb and drain water in order to resolve and mitigate flooding. Next, the excess volume of water flows into green spaces which include a series of ponds and rain gardens. The excess water was precipitated, exposed, purified and absorbed by plants, and eventually flowed into the creek, the river or the sea through underground pipes.

Fig.9: Green roofs and walls

Fig.10: Detail section of green walls

In Melbourne, many buildings drain rainwater from the roof into the road or the ground through the drainage pipe, which aggravates the road catchment. Flood mitigation programs should fundamentally solve and utilize water resources rather than simply divert rainwater elsewhere. For the densely built centre of Melbourne, hard pavements are larger than the green areas, which is one of the important ways to absorb and store water resources.

The advantage of the green roof is that it does not need to be changed radically to the existing urban structureďźŒ and rooftops can constitute 50% of the impermeable areVa in the high-density urban centre (cited in Speak et al., 2013). Green roofs and walls help improve stormwater management by being close to water sources and by reducing the speed and amount of runoff. The green roof consists of three layers - vegetation, substrate and Fig.8: The definition of flooding.

drainage. The deeper matrix layer allows the plants in the vegetation layer to have greater biodiversity. The runoff reduction process includes three parts: the first is to delay the start of runoff; the next is to reduce runoff; finally, runoff is distributed over a longer period of time by slowly releasing excess substrate pore water (Mentens et al., 2006).

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3.2 Permeable street

3.3 Rain garden and vegetation

As for streets using permeable material and drainage pipes to absorb and drainage water. That’s an important

Rainwater from both buildings and streets can be absorbed through green Spaces, especially rain gardens. In the

part because all residential and commercial environment is surrounded by streets. In order to better manage

processes of mitigation rainwater, some of the rainwater above the ground is replenished by permeable material,

rainwater in urban areas, permeable pavement is considered a sustainable drainage method that promotes

and some go into underground drains, the excess volume of water flows into green spaces which include a series

rainwater infiltration and transfers runoff pollutants to the receiving environment, such as rivers, lakes and

of ponds and rain gardens. As for rain garden, rainwater is absorbed through the buffer zone (3) which plants

waterways. The porous surface layer of permeable pavement is the key to receive rainwater. The most common

prefer to drier conditions, slope zone (2) which plants can tolerate occasional standing water and base zone (1)

porous surface layers include permeable concrete, permeable asphalt, interlocked concrete block paving bricks,

which plants can tolerate wetter conditions (Fig.12).

concrete mesh pavers, and plastic mesh pavers (Bentarzi et al., 2016). The permeable material is a mixture of construction wastes, like crushed concrete which is structural support, and organic matter, like compost which is used for retention and the biological treatment of stormwater pollution. They are four kinds of permeable ways on the street, including permeable surfaces that made of permeable material, gutter permeation that creating gutters on two sides of roads in order to absorb water, line type of permeable which means to create dotted lines of permeable material on roads and slot penetration like drainage pipes which constructs under the ground to store water (Fig.11).

Fig.12: rain garden absorbs rainwater through the buffer zone, slope zone and base zone.

Vegetation slope, complementing with the rain garden, is designed to handle more heavy rains (Fig. 13).

The excess water is deposited by plants, exposed to the sun, purified and absorbed by organisms, and can eventually flow through underground pipes into receiving environments such as the Yarra River. Plant growth and metabolism cannot be separated from water, which is a high value for rainwater mitigation. In addition, the growing environment of plants, such as soil, also has the function of absorbing water resources, thus vegetation is an effective tool for dealing with floods. Herbs and woody plants work together to strengthen soil structures that are not easily damaged by floods. Their branches and trunks can be lifesavers when threatened by flood.

Fig.11: permeable ways on the street However, the permeable pavement still has its limitations, and the application of permeable pavement system as the best rainwater management practice is relatively limited and slow (Kuruppu et al., 2019). In the subsequent use of pervious materials, standard maintenance procedures should be developed to restore permeability and improve the structure's carrying capacity to withstand higher vehicle loads and speeds.

Fig.13: Vegetation slope, complementing with the rain garden 18

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3.4 Groundwater recharge

The artificial groundwater recharging equipment includes three main parts. The first is natural recharge from precipitation including processes of runoff and permeate through soil, vegetation and sand. The second is natural recharge from streams flowing into groundwater reservoir. The third part is to inject water into the groundwater

Groundwater is an important source of fresh

reservoir through the drainage pipe with a control value flexibly controlling the flow rate. Groundwater recharge

water all over the world. In some areas where

as an important reservoir in water management, improves drainage efficiency by combining a variety of surface

freshwater is scarce, rainwater is an important

runoff and infiltration water methods, promotes the reuse of water resources and further achieve the long-term

source of freshwater. Rainwater recycling is a

goal of rainwater recycling.

long-term goal that requires complex processes.

In order to achieve this long-term goal, it is necessary to design a series of groundwater recharge methods. Surface runoff, permeable ground, rain gardens and vegetation slopes mentioned above are all part of the groundwater recharge method. This part will focus on Elizabeth street where is the main road to connect commercial and residential areas, in order to more specifically describe strategies for dealing groundwater.

The relative standard water flow routes are a maximum of 5 for the Elizabeth street, but the

Storm cloud

drain pipes diameter is relatively small (figure

Artificial recharge well

14). Thus heavy rainfall in the direction of

Pipe to source of recharge water

surface runoff to the rain accumulation area caused flooding in Elizabeth street. In terms of

Precipitation

groundwater charge method, some rainwater seeps into the ground through permeable surface

Runoff

to rivers through greenbelts, grassy slopes and rain gardens, and some are transported to

Sand

underground water storage layers, where it is reused when needed through pits and pipes.

including water flow routes over land, drainpipes and stormwater pits.

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Stream

Soil water table

Ground water reservoir

Sand and gravel

Fig.14: Elizabeth street existing drainage conditions,

Natural recharge from stream

Control valve injection pipe

materials, some are purified and transported

Natural recharge from precipitation

Bedrock

Fig,15: Artificial recharge under the Elizabeth street.

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4. CONCLUSION

5 REFERENCE LIST

When floods occur in densely populated areas, humans have to face the destruction of property and threats

Andrew, B.(2017) “A brief history of Victorian floods” THEAGE, https://www.theage.com.au/national/victoria/

to life. In recent years, with climate change and urban development, cities are inundated with increasing

a-brief-history-of-victorian-floods-20171202-gzxcem.html

frequency, which means that the situation will worsen in the future. This visual essay is not to criticize the drainage system of Melbourne, but to choose more suitable drainage mode, which can reduce the loss of

Abubakar, T., Ezra, E. A., & Mohammed, C. (2012). SELECTING SUITABLE DRAINAGE PATTERN TO

public property in the event of floods. This information can provide a reference for solving flood disaster and

MINIMIZE FLOODING IN SANGERE VILLAGE USING GIS AND REMOTE SENSING. Global Journal of

rebuilding water harmonious city in the future. Based on the geospatial information of Melbourne, this study

Geological Sciences, 10(2), 129-140. Retrieved from

analyzes a series of geographic and digital information, studies the impact of floods on the region, and shows how digital information provides information about urban and landscape policies to respond to natural disasters.

Bentarzi, Ghenaim, Terfous, Wanko, Feugeas, Poulet, & Mosé. (2016). Hydrodynamic behaviour of a new

By analyzing the existing urban characteristics and conditions, such as the distribution of surface runoff and

permeable pavement material under high rainfall conditions. Urban Water Journal, 13(7), 687-696.

drainage pipes, this visual essay discusses a series of methods to improve the urban drainage system in urban design. It is very important to follow the natural laws of water flow to low flow in a well-designed drainage

Chau, V., Holland, J., Cassells, S., & Tuohy, M. (2013). Using GIS to map impacts upon agriculture from

mode. And designing the drainage system according to the characteristics of the water greatly reduces the

extreme floods in Vietnam. Applied Geography, 41, 65-74.

difficulty. Control the flow of flood water into public Spaces, streets and buildings by using green roofs and walls, permeable materials, rain gardens and groundwater recharge.In addition, these methods guide urban

City of Melbourne open data. https://data.melbourne.vic.gov.au/

planners to explore more appropriate ways to control flood flows, achieve water recycling goals, and create water-harmonious cities.

Kuruppu, Upeka, Rahman, Ataur, & Rahman, M. (2019). Permeable pavement as a stormwater best management practice: A review and discussion. Environmental Earth Sciences, 78(10), 1-20.

Fig.16: rainwater recycling system

Mentens, Raes, & Hermy. (2006). Green roofs as a tool for solving the rainwater runoff problem in the urbanized 21st century? Landscape and Urban Planning, 77(3), 217-226.

News.com.au (2017) “Dramatic images show Melbourne is no stranger to floods” https://www.news.com.au/ technology/environment/natural-wonders/dramatic-images-show-melbourne-is-no-stranger-to-floods/newsstory/d56621a9b6553aee573d3eaab9879d63 Speak, Rothwell, Lindley, & Smith. (2013). Rainwater runoff retention on an aged intensive green roof. Science of the Total Environment, 461-462, 28-38.

Skoglund, J., and H. Hytteborn. "Viable Seeds in Deposits of the Former Lakes Kvismaren and Hornborgasjoen, Sweden." Aquatic Botany 37.3 (1990): 271-90.

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