East African Sustainability

EAST AFRICAN SUSTAINABILITY Plant based systems for stormwater management, erosion control and livelihood improvement

30 ECTS points MSc in Landscape Archictecture Jesper Rasmussen, gbh605 Supervisior: Marina Bergen Jensen Co-supervisor: Marten Sørensen

University of Copenhagen Facultyof Science Department of Geoscience & Natural Resource Management Section for Landscape Architecture and Planing

Jesper Rasmussen March 2019 All photos and diagrams are, unless stated otherwise made or taken by Jesper Rasmussen. For information about other photos, see Pictures.

Unless stated, all plans and maps are oriented north.

EAST AFRICAN SUSTAINABILITY Plant based systems for stormwater management, erosion control and livelihood improvement

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ACKNOWLEDGEMENTS This thesis is the result of a long process that has led me to places on this planet I did not know existed. I have seen some of the terrible impacts of climate changes and met the people who live with the consequences of them every day. I am very grateful to have been given this opportunity to see it all firsthand thanks to all the people who have helped me in the process.

First of all, a great thanks to my supervisor Marina Bergen Jensen and my co-supervisor Marten Sørensen for all the help and encouragement during the process of this thesis. A special thanks to Marina for helping me understand the problems the people of Dar es Salaam are facing now and in the future, giving me inspiration to use my knowledge to help.

Also, a special thanks to Marten for the many talks we have had about tropical botany and the challenges I faced in Dar es Salaam.

I would also like to thank all the amazing people who helped me during my visit in Dar es Salaam. First, thank you to the people at Ardhi University; Given Justin Mhina, Simon Mpyanga, Professor Wilbard J. Kombe and Stephen Emmanuel Mbuligwe for the collaboration and time spent together. I also extend my gratitude to Ronald Ndesanjo from University of Dar es Salaam, for his collaboration and the time he spent with me during my visit in Dar es Salaam.

Additional thanks to the local sub ward leader of Kibululu, Stephen Mecky, for showing me around the neighborhood, introducing me to the locals and showing me the problems that are happening right now.

A special thanks to my private chauffeur, interpreter and new African friend, Mr. Ezekiel, for taking me around Dar es Salaam, telling me stories about how he sees Tanzania and Dar es Salaam, and introducing me to the locals in the areas we visited together.

Lastly, my sincerest thanks to my friends and family for supporting me throughout this process. This work would not have been possible without your great positivity and help.

I know I cannot stop climate change, but this study has shown me how I as a landscape architect, with my specific knowledge and perspectives, can help find ways people can cope and live with the consequences.

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ABSTRACT

Climate changes are the source of many problems, one of which is heavier and more frequent rainfall that causes flooding in tropical areas like the East African regions.

Using the Mbezi river catchment in Dar es Salaam, Tanzania, as a case study, this thesis examines how landscape-based stormwater management (LSM) can create sustainable solutions that manage to combine stormwater management with erosion control and general improvement of livelihood for the area’s inhabitants. The methodology of this project is divided into three working phases; literature search, a field trip for site observations and a design and reflection phase. Through these phases, this study

finds that a combination of large-scale ornamentals and urban farming with a mix of cultivated and wild edible plants can contribute to the improvement of the ecosystem, biodiversity, food security, income, aesthetic pleasure, and thus the general livelihood of inhabitants in the examined case area, while also serving the purpose of stormwater management and erosion control. As such, this thesis lends a broader perspective on stormwater management in East African regions and contributes to its field with conceptual designs of multi-faceted LSM solutions that can potentially inspire similar, if not identical, initiatives in other likewise afflicted areas.

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS ABSTRACT

I INTRO

CLIMATE CHANGES THE UNITED REPUBLIC OF TANZANIA THE CITY OF DAR ES SALAAM FOOD SECURITY IN DEVELOPING COUNTRIES LANDSCAPE-BASED SYSTEMS FOR STORMWATER MANAGEMENT

II OBJECTIVES

11 13 15 19 23 26

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III METHODES & MATERIALS

33

IV RESULTS

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METHODOLOGICAL APPROACH DESCRIPTION OF THE CASE AREA

PLANT LITERATURE AND SELECTION CRITERIA CATEGORIES QUALITATIVE OVERVIEW OF PLANT CATEGORIES RESULTS OF MARKET ANALYSIS LSM PRINCIPLES FIELD TRIP FINDINGS CASE AREA ANALYSIS

8

5 7

35 37

45 46 49 53 54 69 76

V DESIGN PROPSALS

DESIGN CRITERIA TWO SITES - TWO DESIGNS DESIGN PROPOSAL I: THE COMMON AREA DESIGN PROPOSAL II: THE PRIVATE GARDEN

81 83 85 89 95

VI DISCUSSION

101

VII CONCLUSION

107

VIII OUTRO

FINAL REMARKS PICTURES REFERENCES

111 112 114 120

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I

INTRO

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CLIMATE CHANGES

In 2015, leaders from around the globe met up at the United Nations and created 17 sustainable development goals for the future together. The thirteenth of these goals was concerned with �Climate Action�, a goal that was set because climate changes present an urgent challenge, not only for one or two countries, but for every country in the entire world (Undp.org, 2015). Action is needed! The climate changes can still be minimized, but it requires collaboration on a global scale.

The world’s temperature is rising, and the estimation is that around 95% of these changes are the result of human activities.

Climate changes carry have high economical cost for all countries in the world, but they present even greater cost for the people facing the consequences up close and personal (IPCC, 2013). The consequences

of the rising temperature are many: shrinking of the ice sheet, sea level rising, extreme droughts, more extreme precipitation events, etc. Evidence supporting the seriousness of climate change can be found all over the globe (USGCRP, 2017).

Some of the countries that face greatest consequences related to climate changes are developing countries around the world (Mirza, 2003). It is estimated that the Gross Domestic Product (GDP) cost per capita is around 20 times more for a developing country than it is for a developed country (Freeman, 2001). This means that the consequences of climate changes affect developing countries on a different scale than it does developed countries.

Left page - Figure 1: The direct impact of what climate changes can do to the city, here close to the estuary of the Mbezi river.

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Equator

Dodoma Dar es Salaam

Figure 2: Marked in grey is the location of Tanzania in Africa.

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THE UNITED REPUBLIC OF TANZANIA

The United Republic of Tanzania (or just Tanzania) is a very young nation. The country got its name in 1964, when the old English-led colony Tanganyika was united with the old Arabic Zanzibar (Chuwa, 2012). ”Tan” from Tanganyika and ”Zan” from Zanzibar gave the country its name (Wikipedia.org, 2018). Tanganyika used to be part of a large British colony, known as British East Africa. East Africa consisted of Uganda, Kenya, Zanzibar and Tanganyika, and was established in the last part of the 19th century (Britannica.com, 2018a).

Tanzania is located in the south-eastern part of Africa (Figure 2), just below the equator, which places it in a tropical zone.

This means that the average temperature is never lower that 20° C, and temperatures below 0° C only occur in high altitudes. The climate is usually humid and warm, but not all parts of the country have the same climate (Meteoblue.com, 2018).

The country can be separated into four climate zones, mostly distinguished by its topography. The first one is the coastal climate zone which included Zanzibar, second is the central plateaus of the country, third is the north and west areas with their many lakes, and fourth is the highlands in the north-eastern part of the country. These four zones’

climates vary a lot, from warm and humid in the coastal zone, to a cooler climate at the lakes in the north and west. The rainfall is also mostly determined by these zones. In the north and east part of the country, there are two rainy seasons; an intense rainy season from March to May, and a less intense season from October to December. The west, south and central parts of the country only have one, but less intense, rainy season from October to May (USAID, 2018).

Some of the consequences related to climate changes on a national scale for Tanzania are that the central parts of the country will experience up to a 20% a decrease in rain during the rainy seasons, while the coastal and lake regions of the country will experience up to a 50% increase in rain (Hulme et al., 2001).

Short facts about Tanzania

(Wikipedia.org, 2018)

Size 942,800 sq km

Inhabitants 57.31M (2017)

Capital Dodoma

Largest city Dar es Salaam

Language Swahili/English

Independence 1964

Currency Tanzanian shilling

Climate Tropical

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This, combined with the fact that the country faces an average temperature increase of 2.5° C to 4.5 ° C before the year 2080, could mean that the country will face more extreme weather, such as heavier tropical hurricanes, heavy cloudburst and rainstorms, extreme drought and a rising sea level (Kiunsi, 2013). All these different events are likely to have severe consequences, not only for the ecosystem in the country and the agricultural sector, but also for the average person living in the country (Shemsanga et al., 2010).

Tanzania has been classified as a developing country for many years. People living in the country do not have a very high living standard, and many people live a life of outright poverty (United Nations, 2018a). The fertility rate is very high, and the mortality rate is very low (Agwanda and Amani, 2014), which means that the population of Tanzania has grown rapidly over the last 50 years; from around 11.34 million people when it became independent, to around 57.31 million people in 2017. That is a population growth of 405%. In comparison, Denmark’s total population growth in the same time period was only 22%, going from 4.72 million in 1964 to 5.77 million in 2018

(Worldbank.org, 2017). Predictions say that the population in Tanzania will have grown to over 70 million people in 2025, over 100 million people in 2050 (Agwanda and Amani, 2014).

One of the many problems with this rapid growth in Tanzania is that around 50% of the total population is under the age of 17 (Wenban-Smith, 2015). Thus, the future labour force will be huge, and it is unlikely that there will be enough work for all these people. Between 650,000-750,000 people currently get old enough to join the labour force every year, and unemployment in the country is already high; it is estimated at around 2.3 million people (Agwanda and Amani, 2014). An additional problem associated with the rapid population growth is the pressure it puts on the country’s natural resources, such as freshwater and food (Wenban-Smith, 2015). It is likely that producing enough food for the growing population will become increasingly challenging in the future.

Right page - Figure 3: The scale of the city is huge. Notice the down town in the far background of the picture.

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Bagamoyo Rd

Short facts about Dar es Salaam

M

pi ji r

ive

r

Indian Ocean

ir

A7

z be

ive

r

M

z ba sim

riv

er

M

M

ga zin

B2

Figure 4: Greater Dar es Salaam.

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riv

er

(Cia.gov, 2018)

Size Districts 1,393 sq km Ilala Kinondoni Growth rate Temeke 6.45% Kigamboni Ubungo Inhabitants 6.048M (2018)

THE CITY OF DAR ES SALAAM

The name of the city Dar es Salaam originates from Arabic and means ”Port of Peace”, a name it got in 1867 from the sultan of Zanzibar, who founded the city. The city used to be a small, peaceful harbour city that served as a caravan terminal for the sultan, but it has grown many time in size since then both in terms of area and population (Calas et al., 2006).

Dar es Salaam is located the eastern part of the country, facing the Indian Ocean (Figure 4) to the east (Britannica.com, 2018b). It lies around 6.5° south of the equator between the two rivers Mpiji north of the city, and Mzinga south of the city (Baker, 2011).

This places Dar es Salaam in the warm and humid coastal climate zone - with two rainy seasons (USAID, 2018). The city’s annual average temperature is 26.4° C, with an annual average maximum temperature of 31.1° C (Chuwa, 2012). The city has an annual rainfall of between 1,000 and 1,300 mm of rain, and the heavies cloudbursts come during the rainy seasons (Kiunsi, 2013).

estimated, that around 6.048 million people live within the city border of greater Dar es Salaam, a number which only seems to increase further in the future (Cia.gov, 2018).

Dar es Salaam is, much as many other cities around the world, facing the consequences of mass migration from rural areas to more urban areas. Estimations currently say that around 55% of the world’s population live in urban areas, and it is expected that the number will have grown to around 68% in 2050 (Un.org, 2018). In Dar es Salaam the annual urban growth rate was 6.45% in 2012 (Wenban-Smith, 2015), and it is expected to have grown to 9% per year by 2020 (Agwanda and Amani 2014). This is significantly higher than e.g. the capital of Denmark, Copenhagen, whose annual urban growth rate was only 1.76% in 2018 (Velfædsanalyseenheden, 2018).

When so many people, over such short periods of time, move to the city, it is bound to cause some challenges with regards to urban development, especially if the city does not have the necessary regulation to conDar es Salaam is not the capital of Tanza- trol and manage this development. In Dar nia, but it is still the largest city in the coun- es Salaam, a significant consequence is that try measured by population. This year, it is much of the land that used to be forest or

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farmland is now used as sites to build houses and homes for the many new inhabitants.

The authorities do not have the capabilities to handle this massive population growth (Wenban-Smith, 2015) and the city needs a new master plan to control and regulate these settlements around the city. Mainly due to the fact that the last master plan for development of the city was made back in 1979 (Kiunsi, 2013), when the population of the city was only around 807.000 (United Nations, 2018b). One of the consequences of this lack of regulation is that many new settlements in the city are built unplanned, without any consideration for future problems it may cause (Agwanda and Amani, 2014). It is estimated that these unplanned settlements make up around 50% of the total city area (Kiunsi, 2013).

to the city, both with water supply, sewers and stormwater management. Only around 10% of all inhabitants in Dar es Salaam are connected to the sewer system, and up to 70% of all inhabitants use pit latrines, since it is almost exclusively the central part of the city that has a sewer system (Kiunsi, 2013).

Most people do not have any fresh water, and therefore need to get water either by buying it, collecting it from different water sources (e.g. rivers and lakes), or through water harvesting (i.e. collecting rain water) (Baker, 2011).

The lack of stormwater management in the city is easy to see. The city only has around 600 km of piped drainage for the water, and around 1,100 km of open ditches (Kiunsi, 2013). That is not much for a city of its scale, considering that it experiences heavy cloudburst two times a year during the rainy seasons. Thus, the lack of stormwater management leads to significant pressure on the sewer systems during the rainy seasons, which causes heavy flooding around the city (Kiunsi, 2013).

Many of the unplanned settlements in the city are low to medium density and most of them are low rise. The unplanned settlements are often found away from the city centre where much of the land is not built on, and where there is no control over where people build. Many of these unplanned settlements consist of badly built houses Due to climate changes, these rain events made with low quality products. The un- will become heavier, causing more damage planned settlements cause many problems and loss in the city, and since the city is lo-

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cated in the eastern part of the country, the risk of getting up to 50% more rain in the future is substantial (Hulme et al., 2001).

The negligible sewer and stormwater management systems will not be able to handle such enormous water pressure. When heavy rain events occur, the risk of waste water from the sewer system or pit latrines getting mixing with, and thus polluting, fresh water will be great. This could lead to more frequent outbreaks of diseases such as diar-

rhea, cholera and dysentery (Baker, 2011).

Additionally, the pressure will not only be on the stormwater management and sewer systems, but also put added pressure on the existing rivers that run through the city and have their estuary in the Indian Ocean.

This thesis is concerned with the, already substantial, resulting problems and consequences by one of the many rivers in Dar es Salaam; the Mbezi river and the catchment surrounding it.

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FOOD SECURITY IN DEVELOPING COUNTRIES

With the increasing population growth in the cities and with a changing climate, food security in the developing countries is seriously impaired. For Tanzania, and therefore Dar es Salaam, climate changes appear to have substantial impact on food security, which the article Climate Change, Agriculture and Food Security in Tanzania (Arndt, 2012) presents research on. It provides an overview of the impact climate changes have on the agricultural production in Tanzania, and how the yield will be affected by them. It also provides insight into what the consequences would be for different households based on income and consumption patterns (Arndt, 2012). The article argues that the agricultural production of food will be reduced in the future due to the changes in rainfall and rise in temperatures that lead to long drought periods (Arndt, 2012).

With such a decline in the food production in rural areas, the prices on food will rise, which will have momentous influence on the economic situation of large parts of the population, and is thus likely to affect their overall livelihoods (Arndt, 2012). In this thesis, the Arndt (2012) article therefore serves as a basis for looking further into food security and agriculture in an urban perspective. One solution to the problems presented by Arndt (2012) could be the use

of urban farming, where people living in the city can produce (some of) their own food. (Figure 5) That way, fewer resources from rural areas would be needed (Jacobi, n.d.).

This thesis replies on the Plant Resources of Tropical Africa (PROTA) series of handbooks for much the plant knowledge needed to work effectively and sustainably with urban farming. The books are basically an encyclopaedia of utility plant species found in the tropical part of Africa. The encyclopaedia consists of 16 books, describing around 7,000 higher plant species, and covers both cultivated and wild plants. This thesis makes use of three of the books in the series, all of which contain knowledge specifically about plants capable of producing some kind of yield (Brink and Belay, 2007, Grubben and Denton, 2004, van der Vossen and Mkamilo, 2007). The project was stopped in 2013 due to lack of funding, but additional plants can be found online at www. prota4u.org.

The most obvious way to establish food production in urban farming would be to use common cultivated plants that have been used in the area for many years, are easy to grow, and give good yield. In Dar

Left page - Figure 5: An example on how people in the city is trying to grow crops.

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es Salaam, crops from these types of plants would be e.g. pineapples, okras, peppers, eggplants, mangos, papayas, bananas and oranges (Jacobi, n.d.). The downside of relying solely on cultivated plants is that these plants have often been modified and cultivated many times to provide the best possible yield, which makes many of these conventional plants very vulnerable to diseases and extreme weather events such as heavy rain and extreme drought (Ruffo, 2002). This is important to consider for the people growing the plants as it could easily leave them without any yield, and therefore nothing to eat or sell at markets.

Another way to establish food production in urban farming would be to grow edible wild plants (Figure 6). The book “Edible Wild Plants of Tanzania” by the Regional Land Management Unit RELMA from 2002 covers the different phytogeographical regions of Tanzania and gives a good introduction into how to use wild plants as a food source. It thus serves as an important additional source of insight. The book lists four good reason to make a book that documents the edible wild plants found in Tanzania.

First, traditional knowledge and wisdom is dying, and it is important to preserve that.

Second, wild edible plants can, during crop failure and famine, provide an alternative to

cultivated food sources. Third, many wild plants can provide the correct nutrients for a balanced diet. Fourth, that wild edible plants can provide some ”new” plant species in food production (Ruffo, 2002).

Tanzania has many wild plants with edible parts, many of which are indigenous to parts of Tanzania or Tanzania as a whole.

Some of the plants can be found as weeds in the agricultural areas, but many of them are still only found in their natural environment (Ruffo, 2002). The use of indigenous and endemic plants in urban farming would create great opportunities for enhancement of biodiversity in the city. Furthermore, many of the edible wild plants are used in the traditional Tanzanian kitchen, and adding edible wild plants to urban farming could thus contribute to the preservation of many food traditions. Many of the edible wild plants, e.g. Adansonia digitata, can also contribute to overall food security, because they can easily be preserved and eaten during seasons with less food production (Ruffo, 2002). The downside of relying solely on edible wild plants for urban farming is the uncertainty associated with only getting a little yield from each plant, or possibly not getting any yield at all.

Left page - Figure 6: The Ximenia caffra is one of the many wild edible plants of Tanzania.

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LANDSCAPE-BASED SYSTEMS FOR STORMWATER MANAGEMENT

Figure 7: An example of how the WGA project suggest a LSM approach for the Mbezi river (Fryd et al., n.d.)

Stormwater management does not necessarily have to be made using ”grey” systems (i.e. systems made in concrete, plastic or other manufactured materials, such as drainage pipes, drainage canals and other elements made in concrete). Stormwater management can also be made with the use of a ”greener” or perhaps ”blue-greener” perspective, by using landscape based stormwater management (LSM) (Khatib, 2014). One of the significant contributions to this perspective is The Water Resilient Green Cities for Africa (WGA) (Figure 7) project whose aim it was to see how larger African cities, in this case Addis Ababa in Ethiopia and Dar es Salaam in Tanzania,

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could use landscape-based stormwater management (LSM) to increase climate resilience and provide green urban spaces (Ign.ku.dk, 2017). Research in this project focused on whether LSM could provide some of the same services as sewers could have (had there been any), but also to see if LSM could improve water supply and support the general livelihood in the cities. The WGA project is the result of collaboration between three universities1, it ran from September 2013 to August 2017 and consists of several different types of publications; 8 articles, 8 WGA reports, 13 presentations and abstracts, and 3 theses (Ign.ku.dk, 2017).

The project therefore provides its research

area with a great deal of knowledge, and much of the work done in the WGA project forms the basis for how LSM can be used to create green urban spaces in larger African cities - a lot of which is highly relevant to this thesis. In other words, the project paves the way for a closer study on how LSM can be developed in the Mbezi river catchment.

LSM solutions can be part of the green infrastructure (GI), in the city. GI contributes not only to the ecosystem of the city, but also to the quality of life. It enhances biodiversity and reduces the urban heat island effect (Jim, 2012). One of the great advantages to using LSM instead of conventional sewer systems is that stormwater can be kept and used as a resource that contributes LSM solutions could be simple separate wa- to green elements, rather than be regarded ter drainage systems by themselves, or so- as a nuisance that only has to be led away mething part of a larger stormwater mana- from a given area. gement system (Mhina et al., 2018). LSM is based on four natural principles: Retention/ Which plants are used in LSM mostly dedetention, transport/conveyance, infiltrati- pends on where the system is established, on and evaporation/transpiration. Often, and on whether it has a purpose besides the LSM solution is combined with some functioning as a stormwater system. kind of water treatment meant to remove polluted particles from the water. Using LSM solutions in an upstream area of river will impact the downstream areas positively, with regards to both erosion control and flood mitigation (Fryd et al., n.d.), thus improving the livelihood conditions for the people living close to the river.

1) University of Copenhagen, the Department of Geosciences and Natural Resource Management, 2) Ardhi University, Institute of Human Settlements Studies, and 3) Addis Ababa University, Ethiopian Institute of Architecture, Building construction and City Development 1

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II

OBJECTIVES

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OBJECTIVES

The overall objective is to help the people living in the Mbezi river by suggesting sustainable LSM solutions for the area that combines control of flooding and erosion

problems with improvement of the general livelihood conditions through urban farming and large-scale ornamentals. This will be achieved by:

1 - Identifying the plants most suitable for LSM and locating the areas in which small and simple solutions can best make a great impact - both in terms of yield and control of flooding and erosion 2 - Identifying which LSM solutions will be the most sustainable fit for the area, taking the perspective of erosion control and livelihood improvement into consideration, hence reflecting the different needs of inhabitants in the area.

Left page - Figure 8: The opposite of what a sustainable LSM solution can contribute with, are large grey implementations like this stormwater drainage canal.

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III

METHODS & MATERIALS

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METHODOLOGICAL APPROACH

To reach the objectives of this study, three Case area observations studies were conducted: literature search; case area observations, and design.

The second phase involved a three weeks field trip to Dar es Salaam in the beginning Literature search of June 2018. The aim of the field trip was to explore the city and the case area of the The focus of the first phase was mainly on Mbezi river catchment. reviewing scientific literature regarding the overall subject of climate changes and mi- The methods used during the trip were gration from rural to urban areas, Dar es mainly: having talks/interviews with local Salaam, food security, tropical plants, and residents, making photo documentation, water management. Much of the literature exploring the city and case area on a human came from the WGA project and from the scale, making field registrations of plants two large books of African plants; PROTA and prices of plants, looking at challenges, and Edible Wild Plants of Tanzania. As a potentials and limitations in the area, consupplement to the literature, the case area ducting different kinds of on-site analyof the Mbezi River catchment was taken in ses, and collecting plant and map data for for further investigation. further research.

This phase also helped set up different criteria regarding which plants would be useful for urban farming in the Dar es Salaam area, resulting in a preliminary list of both wild and cultivated plants that can be found in appendixes 1 and 2. This phase also helped determine which LSM principles would be most suitable for resolving the problems in the Mbezi River catchment.

Design In the third phase all data and knowledge collected in phases 1 and 2 was analyzed and served as input and basis for the decisions made regarding design criteria for the design proposal.

Left page - Figure 9: Looking at the problems from above. Dar es Salaam seen from above.

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DESCRIPTION OF THE CASE AREA

The catchment of the Mbezi River was chosen as a case area. The area is representative of urbanizing catchments suffering from the consequences of climate change. Some knowledge about the area is already available.

of forest, open land and agricultural spaces, to more residential areas. As noted in the Intro section, these changes have been made without knowledge about the destruction of the green and blue structures of the area (Limbumba et al., 2016).

The Mbezi River is one of the rivers that run through Dar es Salaam (Figure 11). It is one of the small rivers, and it is only around 24 km long, with around 56 small valleys and tributaries, with its source west of the city.

The river runs through the northern part of Dar es Salaam and is located in the district of Kinondoni. It runs through three ward areas, Mbezi, Goba and Kawe. These areas are further separated into 13 small sub ward areas.

The Mbezi River has its estuary at Mbezi Beach, approximately 12 km north of the city centre (Mhina et al., 2018). The area around the river, the Mbezi river catchment, consists mostly of undulating hills, although it also has steeper hillsides as well as a flatter area close to the estuary at Mbezi Beach (Figure 10). The undulating hills cover around 90% of the total catchment area (Fryd et al., n.d.), which has a total size of 56 sq. km (Mhina et al., 2018). The use of the land has changed a lot, from a mixture

Settlements in the catchment area are a mix of unplanned unlicensed houses and licensed houses, with the majority built as low-rise structures. The density of the houses in the catchment is generally low, mostly consisting of small settlements or separate plots with houses. Medium- to high-rise buildings are found in the catchment, but only in the sub-city centres or at the two main roads through the area, Bagamoyo Road and Mogoro Road (Fryd et al., n.d.).

Most of the houses are built away from the river, although it is not impossible to find houses very close to the river. Most of the housing facilities in the catchment do not have any kind of stormwater management systems or drainage systems, and there is no common plan for stormwater management (Mhina et al., 2018). Most of the houses merely drain water away from their own plot (Limbumba et al., 2016) without considering whether the capacity of the river can handle the amount of water.

Left page - Figure 10: The Mbezi river shows clear signs of erosion from the last rainy season.

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Bagamoyo Rd Indian Ocean

The Mbezi River

A7

B2

Figure 11: Figure XXXX: The location Greater of Dar theesMbezi Salaam.

River in Greater Dar es Salaam.

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The catchment area does not have many public green spaces. Most of the green spaces are found along the banks of the river and consist mostly of small agricultural spaces or vegetated riverines or trenches (Limbumba et al., 2016). Along the river, two military zones provide large green spaces. Changanykeni military zone is found on the south bank of the river, close to the area of Kibululu, with approx. 3.8 sq. km of the area in the catchment, and Makongo military zone is found on the south bank of the river, close to Bagamoyo Road, with approx. 1 sq. km of the area in the catchment.

These two areas do not allow civilians access, but seen from a satellite perspective, consist mostly of dense forest.

The Mbezi River catchment lies in the zone where heavier rainstorms and cloudburst are expected in the future (Hulme et al., 2001). With people building unplanned housing and settlements along the river, without considering the existing blue and

green ecosystem of the catchment, the risk of causing further damage to the area is high. It is illegal to build less than 60 meter from the river, but many house still get built in that zone (Mhina et al., 2018). When the water pressure on the river intensifies during heavy rain events, damages along the river could therefore be highly destructive.

Based on knowledge from the WGA project, especially the work done in �Mapping the Gap of Water and Erosion Control Measures in the Rapidly Urbanizing Mbezi River Catchment of Dar es Salaam� (Mhina et al., 2018), the three areas of Luis, Kibululu and Ukwamani, all in the Mbezi River catchment, were selected for further investigation aimed at determining the best possible area to implement this project’s design proposal. Luis is located in the beginning of the Mbezi river, Kibululu in the middle and Ukwamani in the area closes to the estuary (Figure 12).

Next page - Figure 12: The Mbezi River catchment, with the locations of Luis, Kibululu and Ukwamani.

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THE MBEZI RIVER CATCHMENT

Luis

A7 Dodoma

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Bagamoyo

Ukwamani

Kibululu

Bagamoyo Rd

Dar es Salaam C

A7

Nelson Mandela Rd

1:45,000

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IV RESULTS

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PLANT LITERATURE AND SELECTION CRITERIA

Part of the way this thesis seeks to achieve its main objective is through the identification of the plants most suitable for LSM in the Mbezi river catchment. This identification process resulted in the construction of two specific plants lists; Appendix 1 (Cultivated plants) and Appendix 2 (Wild edible plants) which are based on different, but very important criteria. These were set up using existing knowledge about the Mbezi area: the Mbezi river lies at a low altitude dry area close to the coast, it has two rainy seasons, many hours of sunlight and high temperatures all year round.

One of the most important criteria for all the plants selected for the lists is that all the plants must, at least in part, be edible in some way. As such, plants used solely for fibres, fire wood or timber have not been considered. These plant groups may also be of possible use in urban farming, but the time required for these plants to grow to harvestable size would simply be too long.

By using plants with some kind of edible part, the time from planting or seeding to the first harvest can be very short, although this is dependent on which plant is used.

This means that the people growing these plants can quickly either get food for their

own consumption or get some money from selling the crops.

Another very important criterion for all the plants selected is that they can function in a sustainable LSM solution. Therefore, the ecology of the plants is very important.

Knowing that the LSM solution is not always in a wet area, but that it can also be very dry, it is important to identify a variety of plants, with different demands of soil, to grow in these areas.

It is also an important criterion that the plants not just provide an edible part and yield well, but also contribute to the general ecosystem and have the ability to enhance the overall biodiversity of the Mbezi area.

Therefore, it is important to identify a selection of both cultivated and wild edible plants that can be mixed in the LSM solutions. The cultivated plants can hopefully provide a good yield in the establishment phase, providing the inhabitant with an incentive to maintain the LSM solution. Then the edible wild plants, which contributes to the enhancement of the ecosystem and biodiversity in the area, have time to grow and over time, hopefully, they will provide new and different crops to the people maintaining the LSM solutions.

Left page - Figure 13: The importance of people being able to produce something to sell, could have a great impact on the livelihood.

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CATEGORIES

Based on the criteria for which plants would Appendix 2 are described using the followbe useful for urban farming in a sustainable ing categories: LSM solution, the plants in Appendix 1 and

Category I: Type The plants are separated into four categories: Trees, herbs, climbers or shrubs. Some plant species are marked both as a herb and a shrub. This is because some of the plants are e.g. woody herbs or shrubby perennials (such as the Abutilon mauritianum). Additionally, some plant species are marked as both shrub and tree. This is due to the fact that some of the plants are found either as a shrub or a small tree (such as the Antidesma venosum).

Category II: Size Here, the plants are described either in terms of their maximum height or in terms of their normal size/height range.

Category III: Ecology This section concentrates on the growing conditions for the plant (e.g. whether the plant prefers direct sunlight or shade), which kind of soil is most optimal for the plant, and what altitude is the most optimal, etc. For the edible wild plants, it is also important to know what their natural habitat is, and whether they are indigenous.

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Category IV: Uses This section describes which part of the plant is the edible part; whether it is a fruit, vegetable, cereal, root or tuber. Some of the plants have different edible parts (e.g. both fruit and leaves can be eaten), therefore they are accounted for in both those categories. Leaves are considered a vegetable.

Some of the plants have uses outside of just producing some kind of edible part. For example, a plant could have parts used for medicinal purposes, beverage production, or oil production. Although it is not a criterion that the plant has any uses outside of edibility, this information has been included in the list so these factors are known as well.

Many of the plants chosen can also be used for their large-scale ornamental value. Ornamental value has not been a deciding factor, but it has been considered a �bonus� for the plants and will be used in the design proposal.

Category V: Values This section sees the plant both from a practical and an aesthetic point of view. The section is focused on what the plant contributes with. This varies depending on the plant and could be anything from its max yield to its beautiful large flowers.

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Figure 14: The Ananas comosus is one of many well-known cultivated crop

Figure 15: The Ziziphus jujuba is a good example of one of the many less known edible wild plants, but have great potentials of being used in urban farming.

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QUALITATIVE OVERVIEW OF PLANT CATEGORIES

The following section (next two pages) presents an overview of the amount of suitable edible plants (both cultivated and wild) based on the criteria stated above. Each table separates the plants into four types: trees, herbs, climbers and shrubs. However, there will be overlaps as some of the plants can be classified in several ways (e.g. as a shrub and a tree) and are therefore accounted for in all relevant categories. Similarly, some of the plants can grow in different soils, while other can only grow in one specific type.

ct sunlight, while only a few can thrive in shadow. Most of the plants produce fruits or vegetables, and a few of them also have edible roots and tubers.

These numbers gives a good sense of the amount of plants that would be suitable for specific areas, and what types of yield can be expected.

The tables clearly show that there is great variety in the plants suitable for urban farming in the Dar es Salaam. Most of the plants, both the cultivated plants and the wild plants, seems to grow best in dire-

The Ananas comusus (Figure 14) and the the Ziziphus jujuba (Figure 15) on the left page, is two examples of a cultivated and a wild edible plant, which would be suitble for urban farming usage.

The numbers also show that there are more wild plants than cultivated plants suitable for urban farming in Dar es Salaam.

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Cultivated Plants - Appendix 1

Growth habitat types Abiotic factors

Growth habitat types Abiotic factors

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Wild Plants - Appendix 2

Growth habitat types Abiotic factors

Growth habitat types Abiotic factors

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RESULTS OF MARKET ANALYSIS

Registration of Plants

and the prices they are sold at. The full registration of all the plants, as well as their priAll plants registered were placed on maps ces and uses, can be found in Appendix 4. with the use of GPS in order to get the exact location, thus making it easy to find them These registrations were made in order to again. The full registration of all the plants get an idea of which plants are easily accesand their positions can be found in Appen- sible in the city, as they would be easiest to use. Their prices were registered in order to dix 3. make it easier to calculate a price estimate for the establishment of the LSM solutions.

Registration of Plant Prices However, it should be noted that the prices The small outdoor plant shops along the listed in the appendix were dubbed “white roads in the city offer a variety of different man’s prices” by a reliable local. He explaiplants (Figure 16). To get an idea of which ned that the plant prices given to a white plants are commonly sold, and at which foreigner are generally higher than what loprices, two small shops in the area were cals would be able to buy them for. Therefochosen at random. There, full registrations re, the price estimates for the LSM solutions were made concerning what plants they sell presented in this thesis are likely to be more (both crops and ornamentals), their sizes, expensive than they would be in reality.

Left page - Figure 16: The small plant shops sell many different kinds of crops and ornamentals

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LSM PRINCIPLES

LSM solutions often consist of different LSM principles. The following section shows six of the most commonly used principles; infiltration trench, swale, canal/gutter, dry basin, wet basin and rain garden.

These six LSM principles all come from four basic water principles: infiltration, transpiration, retention and conveyance (Figure 17 to 20). The LSM principles are not necessarily built on all four basic principles, e.g. a swale (Figure 30) uses three; conveyance, infiltration and some kind of transpiration.

The plants used in the six different LSM

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principles shown in this study (Figure 21, 30, 39, 48, 57 and 66) are a selection of some of the plants from Appendixes 1 and 2, and they can easily be exchanged with others from the appendixes. However, it is important to choose plants that grow under the same conditions and have the same aesthetic expression. The design proposals do not necessarily exemplify all the principles, but they are both built on them.

Figure 17: Infiltration

Figure 18: Transpiration

Figure 19: Retention

Figure 20: Conveyance

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Infiltration trench

Figure 21: Principle for an infiltration trench

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Cultivated plants

Figure 22: Allium sativum

Figure 23: Ipomoea batatas

Figure 24: Musa

Figure 25: Phoenix dactylifera

Wild plants

Figure 26: Celosia trigyna

Figure 27: Dactyloctenium aegyptium

Figure 28: Lobelia fervens

Figure 29: Ziziphus jujuba

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Swale

Figure 30: Principle for a swale

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Cultivated plants

Figure 31: Capsicum annuum

Figure 32: Cucumis melo

Figure 33: Musa

Figure 34: Zingiber officinale

Wild plants

Figure 35: Amaranthus spinosus

Figure 36: Ampelocissus africana

Figure 37: Cordyla africana

Figure 38: Ximenia caffra

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Canal/gutter

Figure 39: Principle for a canal

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Cultivated plants

Figure 40: Ananas comosus

Figure 41: Citrus sinensis

Figure 42: Praecitrullus fistulosus

Figure 43: Zea mays

Wild plants

Figure 44: Coccinia grandis

Figure 45: Englerophytum natalense

Figure 46: Hyphaene compressa

Figure 47: Kigelia africana

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Dry basin

Figure 48: Principle for a dry basin

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Cultivated plants

Figure 49: Cocos nucifera

Figure 50: Mangifera indica

Figure 51: Passiflora edulis

Figure 52: Psidium guajava

Wild plants

Figure 53: Acacia nilotica

Figure 54: Annona senegalensis

Figure 55: Sterculia africana

Figure 56: Tamarindus indica

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Wet basin

Figure 57: Principle for a wet basin

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Cultivated plants

Figure 58: Azadirachta indica

Figure 59: Carica papaya

Figure 60: Mangifera indica

Figure 61: Oryza sativa

Wild plants

Figure 62: Abutilon longicuspe

Figure 63: Dovyalis abyssinica

Figure 64: Typhonodorum lindleyanum

Figure 65: Uapaca sansibarica

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Rain garden

Figure 66: Principle for an rain garden

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Cultivated plants

Figure 67: Mangifera indica

Figure 68: Oryza sativa

Figure 69: Persea americana

Figure 70: Syzygium comini

Wild plants

Figure 71: Adansonia digitata

Figure 72: Garcinia livingstonei

Figure 73: Phoenix reclinata

Figure 74: Syzygium guineense

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FIELD TRIP FINDINGS

This section presents the field trip findings that serve as reasoning behind the final choice of specific site for implementation of the LSM solutions. It provides insight into the three areas that were considered for the project, Ukwamani, Kibululu and Luis, and analyses the challenges, limitations and potentials found in each of them.

The Ukwamani Area Ukwamani covers a total area of 4.2 sq. km, and is an entirely unplanned slum settlement populated by people with low incomes (Mhina et al., 2018). The area lies at the south bank of the river, around 1.8 km from its estuary. Many of the challenges in the area stem from the fact that many of the houses and sheds in the area lie within the 60 meter no-build zone mentioned in the previous section (see “Case Area: The Mbe-

zi River�), and that the area is very densely packed. Many of the houses in the no-build zone show clear signs of the last flooding in the area as parts of them have been destroyed. The alleys between the houses are often very narrow, and some of them have the distinct stench of faeces and urine hanging in the air. The area has almost no visible green spots, no small gardens or unbuilt land. Any open areas are most often used as waste-dumping sites. Additionally, most of the area seems very flat (i.e. there does not seem to be any notable differences in elevation). All of this presents very significant limitations that make LSM solutions largely unsuitable for this area. To better protect the area from floods in the future, action needs to be taken further upstream.

That way, LSM solutions could limit water pressure in the river, which would hopefully prevent further damages.

Left page - Figure 75: Ukwamani seen from the Mbezi river.

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The Kibululu Area Kibululu covers a total area of 4.6 sq. km, and is an unplanned settlement mainly populated by people with medium to high income (Mhina et al., 2018). The area lies at the north bank of the river, around 8,5 km away from the estuary, which places it at around the midway point between the source and estuary of the river. Besides the Mbezi river, small tributaries run through the area, many of which have their source on top of the hills in the area. Houses in the area are located on single plots surrounded by open land, or situated in small neighbourhoods that often have small common areas. Few houses (mostly sheds) are found within the 60 meter no-build zone from the riverbed, and most of these belongs to poor people living in the area. The area is very hilly, and many of the larger houses are found on top of these hills, while the small neighbourhoods are placed further down the hillsides, with small houses and sheds situated closest to the river or tributaries.

Many of the open areas are somewhat bare, with almost no high vegetation, and are mostly covered by grass. Only a few areas

close to the river are used for urban farming One of the most obvious challenges for the area is that it has immense problems with gully erosion, which means that more and more land gets washed away during heavy rain events. The challenges seem to start at the top of the hills, where many of the houses lead water away from their property, and directly out into open land. This runoff creates small gullies in the open landscape, which further downhill lead to very deep and wide gullies where they then reach the Mbezi river. Thus, the challenges in this area mainly lie in finding a way to get people in the area to manage the water on their own property instead of leading it directly out into the open land, or alternatively in finding a way to stop the water from creating the aforementioned gullies. The area offers great potential for the implementation of LSM solutions of different types and sizes that could also contribute to increasing the very limited biodiversity in the area. There are many places in the area that can be used, and quite a bit of potential for the kind of erosion control that would prevent the water from being led into open areas.

Left page - Figure 76: Woman tries to climb one of the large side of a erosion gully in Kibululu.

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The Luis Area Luis covers a total area of 7.8 sq. km, and is a semi-unplanned settlement, mainly populated by people with medium to high income (Mhina et al., 2018). The area lies at the north bank of the river, around 14 km away from the estuary, close to the source of the river. Because the area lies so close to the source of the river, many small tributaries can be found there. The houses in the area are typically located on single plots surrounded mainly by farmland, situated in small dense neighbourhoods or as built as small houses and sheds scattered closest to the river or tributaries. The small neighbourhoods do not always have a common area, because most empty spots are used for farming. Only few houses and sheds are placed within the 60 meter no-build zone.

Most of the houses are situated in the aforementioned small neighbourhoods, all of which seem to be scattered around the area.

The area is very hilly, and the hillsides are often used for farming.

erosion problems; only a few gullies can be found in the area. The reason seems to be the great amount of farming spread around the area, as these use most of the water for crop production. The crops grown in the area appear to be only well-known crops, such as Musa, Ananas comosus, Carica papaya, Persea americana and Cucumis melo.

All the farms in the area could have negative effects on the ecosystem and general biodiversity in the area. Interviews revealed that many of the small farmers use fertilizers, herbicides and pesticides, all which have negative effects on the ecosystem. Many of the plants found outside the farming areas are cultivated or ornamental plants. The area offers plenty potential for the implementation of LSM solutions of different types and sizes, but with all the farmland in the area such solutions would have to be focused on somehow keeping the water in the area, potentially by gathering it in larger ponds.

Interviews with local residents provided insight into the main challenges for this area, which is the lack of water during dry periods. The area does not suffer much from

Left page - Figure 77: A clear sign of erosion on a street in Luis.

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Based on the findings described above, the best area for making LSM solutions with great impact appears to be the Kibululu area. The area shows clear signs of immediate need of action to save the area from eroding away, and offers many places in which simple solutions can be established. The

establishment of LSM solutions in Kibululu would keep much of the rain water in that area, only leading some of the rain water that falls during heavy rain events into the Mbezi river. This will benefit both the Kibululu area and the areas further downstream.

Left page - Figure 78: A clear sign from Kibululu, of how important it is, that something needs to be done now.

The locals throw garbage in the gullies, to prevent further erosion problem. This garbage will sadly at a point, end in the Indian Ocean, when it is washed away from the area.

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CASE AREA ANALYSIS

The catchment area has a total length of around 20 km and starts in an altitude of around 230 MASL. Figure 79 shows how the river runs through the catchment, and how the top of the hills around the river lie in relation to the river itself. It also gives an idea of where in the catchment the areas of Luis, Kibululu and Ukwamani are located, and thus how the river affects these areas.

Figure 80 to 83 (next page) are the result of observations made on site.

Figure 80 shows there are some large green areas throughout the catchment. However, most of these large green areas belong to the military and are therefore not open to the public.

Figure 81 shows how the density of the settlements changes throughout the catchment.

In the western part of the catchment area, the density is very low, with a great deal of space between most houses and many of the

230 m 20 km

LUIS Figure 79: Transect over the entire Mbezi River catchment.

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small settlements. Moving further east, the density gets higher, and closest to the estuary (where Ukwamani is found) the density is highest, with little to no space between the houses.

Figure 83 shows where in the catchment most erosion related problems are found.

The center area and close to the estuary are most affected, while only a few areas in the western part of the catchment seem to have problems with erosion. This is due to the The roads in the catchment area are mostly fact that there is always more water closer just dirt roads, and as Figure 82 shows, only to the estuary than at the top of the catchthe few larger and paved roads moving th- ment. rough the area have storm water solutions.

KIBULULU

UKWAMANI

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Figure 80: Location of larger green areas.

High density Medium density

Low density

Figure 81: Settlement density in the area.

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Figure 82: Paved roads in the area with storm water drain

Figure 83: Extensive erosion problems

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V

DESIGN PROPOSALS

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DESIGN CRITERIA

In this study, design criteria are based upon the field trip experiences and findings described in detail in the sections above. They constitute a number of requirements that

the new LSM solutions in the Mbezi area must meet in order to be deemed successful, and are summarised succinctly in the following bullet points:

•

Must prevent further erosion problems

•

Must be green and sustainable

•

Must help improve livelihood

•

Must be cost-efficient - establishment must not be overly costly

•

Must include the perspective of urban farming

•

Must contribute to greater rural health

The designs are focused on erosion control focus on how to minimize, and ideally prerather than erosion carement. Therefore, vent, further erosion problems in the fututhe designs will not focus on solutions that re. manage existing erosion. Instead, they will

Left page - Figure 84: This is what the design solutions hopefully can help prevent in the future.

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TWO SITES - TWO DESIGNS

This part of the thesis proposes two conceptual LSM design solutions for two different parts of the Kibululu area where the effects of the LSM solutions would make the greatest impact. The first of these designs focuses on common areas in the small neighbo rhoods in the area, and the second focuses on private gardens on top of the hills in the area.

Both designs are conceptual and based only on some of the areas in Kibululu. There are two reasons the design proposals could not be more concrete: 1) it was difficult to obtain permission to measure and do experiments in the areas, especially in private

gardens, 2) the maps that could be obtained lacked the data necessary for more precise calculations. As such, the designs should be seen as inspiration and ideas on how to design areas with a similar purpose, not concrete suggestions that can be directly implemented.

An advantage of the conceptuality of the designs is that it makes them broad enough to draw inspiration from to create similar, if not identical, designs in other areas of Kibululu, the Mbezi river catchment, and even other catchment areas in Dar es Salaam that deal with similar problems.

Left page - Figure 85: Inside the small common areas, nothing but a single tree is often found.

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Makongo Juu - Goba Road

KIBULULU

Kibululu river

Changanykeni military zone

Figure 86: The Kibululu area.

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Private garden

Mbezi river

Dar es Salaam C

Common area

1:5,000 87

84

83

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DESIGN PROPOSAL I: THE COMMON AREA

Figure 88: The small common areas is often only used for laundry, cocking and burning of household waste.

A small common area can be found in many of the small neighbourhoods around the area. It is often found down the hillsides, but not too close to the river or the tributaries. Much of water in this area comes from the runoff of the roofs, which is led out to the common area. From there, the water can pass on freely, down towards the river or the tributaries.

The people who inhabit these places are mostly of average to low income, and they can afford to occupy a small house, often with a small garden, only because the settlement is unplanned (i.e. they did not need to buy they plot, only to build a house). Many inhabitants are unemployed.

Left page - Figure 87: Overview over the common area as it is at the moment.

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Figure 89: Concept

Concept During heavy rain events, water from the lead the water away, but to keep it as a varooftops is led into the common area from luable resource. Therefore, urban farming the houses surrounding it. The goal is to is introduced to the common area, for the inhabitants to share.

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Figure 90: Infiltration trench

Figure 91: Swale

Figure 92: Dry basin

Figure 93: Rain garden

LSM principles used Infiltration trench - Infiltration. Provides Dry basin - Detention, dealing with heavy rain events. Some infiltration. water to the surrounding.

Swales - Transport of water and infiltration

Rain garden - Infiltration, evaporation.

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84 Section 1

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+ 82

82

+ 80

.5

The new design

Before, the common area as a dry piece of land between the small houses. The new design for the area provides more water to the soil, and makes it possible to grow more edible plants. Two swales lead water to a large rain garden in the top centre of the area, while a small dry basin in the lower right corner provides great detention of storm water, until it can be lead away from

Infiltration trench

the area and into the surrounding gardens when needed. The area can still be used for cooking and laundry, but now in a greener and more pleasant environment, with many great fruits and vegetables to use.

With this design, most of the storm water will be kept inside the area, thus leading little to no water further down the Mbezi River

Rain garden

Figure 95: Section 1

Left page - Figure 94: Overview over the common area after new design is implemented.

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96

97

98

98

97

96

6

95

94

93

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DESIGN PROPOSAL II: THE PRIVATE GARDEN

Figure 97 : A high income house, well protected from the surrounding problems. Not a single tree or bush is to be seen in the garden of the house.

The Private gardens are often found on the top of the hills, where the best view over the area is, and where the problems are fewest.

Rainwater is not a problem here, mostly because when there is an excess of rain, the water is simply led away from the garden, without thought of its destination or the problems it causes there.

The people living in these areas are often of a higher income. They have jobs, which makes it possible to build large houses that protect them from their surroundings. The gardens that accompany these houses are often paved or plated with some kind of stones, to make access easier and to provide room for parking. Often, these gardens are nothing more than space around the houses

Left page - Figure 96: Overview over the private garden as it is at the moment.

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Figure 98: Concept

Concept The goal is to keep all the water on the pro- Another goal is to make the garden a place perty, both during normal and heavy rain for the inhabitants to enjoy, giving it a green events, so no water is led out into the open. and simple but exclusive feel.

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Figure 99: Infiltration trench

Figure 100: Canal

Figure 101: Wet basin

Figure 102: Rain garden

LSM principles used Infiltration trench - Infiltration. Provides Wet basin - Retention and evaporation, fish water to the surrounding. to keep mosquitos away.

Canal - Transport of water.

Rain garden - Infiltration, evaporation.

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Section 1

97

96 98

+ 93

+ 95

97

+ 99

98 95

+ 97

Section 1

+ 93

97

+ 94

96

94 + 93

95

+ 94

The new design

The new garden design has small raised paths around the garden, ending in small viewing platforms, where the owner of the garden can watch the garden without stepping into it. At the centre of the garden is a large Baobab tree (Adansonia digitata), reminding one of the wild nature that is one of the country’s greatest attractions. The plants in the garden provide many delicious fruits and vegetables, both well-known cultivated ones and wild ones.

Rain garden

The LSM solutions installed in the garden will keep all the water inside the garden, either by infiltrating through the infiltration trenches around the walls of the garden, or through the three large rain gardens.

Canals around the garden will transport water around the garden during heavy rain events.

Wet basin

Infiltration trench

Figure 104: Section 1

Left page - Figure 103: Overview over the private garden after new design is implemented.

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VI

DISCUSSION

101

DISCUSSION

The main advantage of both the design solutions is that they can help slow down or fully prevent runoff water from leaving the LSM solution areas during heavy rain events, which would diminish the risk of further erosion problems in the surrounding areas. There are, however, also disadvantages. One of these is that the areas in which the solutions would be established currently have purposes not related to LSM. For example, the common areas in the small neighbourhoods are used for many community activities (e.g. as cooking facilities, playing area for the small kids and laundry). An urban farming LSM solution would mean that some of these activities, if not all of them, would need to be done someplace else. During heavy rain events especially, as access through these areas will be impeded by excess rain water and moist soil. A way to solve this particular problem would be to create paved paths through the area, where it would be possible to walk even when the LSM area is filled up with water. However, paving costs a lot of money; money that people in these areas do not have. A different solution could be to only detain the water for a while, and then lead it away from the area in swales and gutters when the areas further downhill can take more water. This

102

would solve some of the problems with accessibility and ensure that the area’s inhabitants could still use the common areas for the activities they do now. A pronounced disadvantage of this approach, however, is that such a solution would cost more money as it is more technical. Additionally, the water would not have enough time to infiltrate the soil, which could otherwise have improved the general soil quality and created a more sustainable solution.

Regarding the private gardens, one significant concern lies in how to convince the owners of the properties lying on top of the hills, not to just lead the water away from their own properties. The LSM solution has to somehow give enough incentive to spend money on establishing the solution. One of the advantages that could be highlighted is that adding LSM solutions keeps all the water in the garden, which would provide a great amount of water to all the garden’s plants as well as create beautiful rainwater ponds. This would make the gardens visibly greener and provide beautiful private spaces for the owners. However, it does present some risk, as an exorbitant amount of rain would mean that water could fill up the LSM solution and cause problems to the

house or the garden. A risk-mitigating initiative could be to harvest the water in large tanks underground, thus saving the water for dry periods where it can then be used to water the garden. Again, however, there are additional costs associated with the solution. Underground tanks for water will increase the cost of establishing the solutions, which could affect the owner’s willingness to participate in the project. It should also be noted that the retention ponds with excess rain water could easily become a habitat for mosquitoes and other insects that would be a nuisance to the garden owners.

Again, this would not be a problem if they chose to install underground water tanks.

Should they, however, value the beauty of the ponds in their gardens, a different solution could be plants that function as mosquito repellents (e.g. the neem tree, Azadiractha indica (Appendix 1 pp. 16)) or fish that eat the mosquito larvae.

Another great advantage of both solutions is that they provide new and sustainable plant-based systems to the area. As previously stated in this thesis, many plants are not very expensive if they are purchased at the local markets. Furthermore, establishing a green LSM solution on a small scale

would not take very long. With the help of local residents, and a bit of money to buy crops at local market (this money could come from e.g. international help organizations and funds), the LSM solution could be established within a fairly short timeframe.

However, green solutions also need time to settle and grow, which could ultimately take several years. A faster alternative could be the kind of grey solutions that are already seen around the city. This way, instead of just leading the water away from the area and down to the river where it would cause even more problems (as is done now), large detention ponds would be established. All the rain water would be led into those through pipes and open gutters. This kind of solution would be very efficient and create great results very fast; maybe it could even be a way to fully prevent further problems in the area. It is, however, a very costly solution and it seems as though the authorities lack the required funds, as well as the willingness, to put in such a stormwater management solution. It is also a very bland and non-sustainable solution that contributes to nothing other than its chief purpose of removing water quickly. A grey solution like that would not contribute in any way to the biodiversity of the city, and it would

103

need to use huge areas as water ponds. Water ponds that are exactly the types of areas that provide good habitats for mosquitoes.

And without the solution of mosquito repellent plants that could be implemented in a greener initiative, problems with mosquitoes carrying malaria would likely increase.

The advantages of combining the LSM solutions in the common areas with a mixture of cultivated and wild plants for urban farming are many. The solution provides the inhabitants with greater food security, as it provides a good foundation for growing crops that could either be sold at local markets or kept for consumption. It also contributes to the ecosystem and biodiversity of the area. However, as people in the area need to maintain the plants themselves in order for the solution to work as an urban farming initiative, this carries some inherent uncertainties and risks of failure; there is no guarantee the area’s inhabitants will actually do this. For one, it requires some level of organisational skills and a willingness to learn. There is also the issue of incentive, and of adequately communicating the advantages of the initiative in a way that produces this vital incentive. Incentive could also be affected by future occurren-

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ces. For example, some of the wild plants could bring diseases with them that could affect or downright ruin the harvest of the cultivated crops. This might remove the incentive to maintain the wild edible plants at all. In essence, small failures may have large consequences. Only using cultivated crops in urban farming may lessen the risk of these kinds of failures. However, that would not contribute to the ecosystem and biodiversity, and it would weaken the inhabitants’ food security as they would not be able to try new crops that might work better and provide greater yield than the cultivated plants do. Removing the possibility of crops entirely (be eliminating urban farming in the LSM solution) would likely also greatly decrease the incentive to maintain the LSM solution, as the immediate advantage (i.e. crops) of doing so would disappear. Instead, there would only be the long-term advantage of handling rain water, and it is uncertain whether or not that would be enough. Thus, it would be less likely that the LSM solution would be successful in the long run.

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VII CONCLUSION

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CONCLUSION

Like many other cities around the world, Dar es Salaam faces the consequences of mass migration from rural areas to more urban areas. Without the regulation and control needed to manage the massive urban growth, cities like Dar as Salaam experience various associated challenges, some of which are closely packed unplanned settlements that decrease the amount of green areas, while creating a need for extra water supply, sewers and stormwater management that the country’s government cannot accommodate. Hence, consequences such as heavy floods and erosion problems are a common sight in the greater Dar es Salaam. This study aims to address these issues, using the Mbezi River catchment as a case area.

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is retained and used as a resource on-site – and is thus prevented from causing any damage further down the river. Thus, in addition to helping the local areas in which these solutions would be implemented, the fact that the LSM solutions proposed in this study keep rainwater in the local areas means that the poorer settlements further downstream, the ones who experience the worst of the flooding, will see a decrease in the amount of water they have to contend with.

Combining the aesthetically pleasing attributes of plants with a practical storm water and urban farming solution, this study designs a well-rounded LSM solution to erosion problems around the Mbezi River catchment.

Since the two designs are conceptual, it is impossible to state with certainty, that they will solve all the erosion problems witnessed by the Mbezi River. However, since most of the excess water would not enter the surrounding areas, it is very likely that there would at least be less damage caused in the future. In using both cultivated and wild edible plants for urban farming, the designs brought forth in this study also contribute to both biodiversity and food security in the city.

With implementation of LSM solutions in both the common area and at the private garden, much of the rain water which would normally be led out into the open,

On a social level, the goal is for these green areas to flourish in a way that encourages similar implementation elsewhere, hopefully creating a need for a workforce to handle

this process as well as maintenance of the plants and crops. This would provide job opportunities for the unemployed residents of the concerned areas in Dar es Salaam. At the very least, income could be achieved by selling the crops at local markets. Either way, increased income and/or increased food security, in addition to fewer issues with rain water, would certainly improve the livelihood of the poorer inhabitants of Dar es Salaam.

In conclusion, this study exemplifies how even small implementations of stormwater management, if implemented in the right places and designed with the right expertise, can have great bearing on many areas of human life in places such as the Mbezi River catchment.

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VIII OUTRO

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FINAL REMARKS

There are a lot of challenges to doing a study like this in a country like Tanzania, especially in the kind of informal settlement areas that were investigated in this study.

For one, it was difficult to get the chance to do measurements and experiments in the areas during visits. Secondly, the maps that could be obtained lacked the kind of data necessary to make precise calculations for sizing the LSM solutions. The lack of precise measurements and data made it impossible to put together a thorough and detailed design solution that took specifics like area dimensions and soil infiltration rates into account. Therefore, the design proposal in this study ended up far more conceptual than concrete.

veral locals and warned against it due to the fact that it would be extremely dangerous to go there. Therefore, the plant price analysis was instead conducted in grocery stores around the city. Upon further deliberation and the subsequent information that prices were significantly higher there than what locals would get by selling their produce on the markets (e.g. the price of a large pineapple in a grocery store was up to 9,000 TZS2 apiece and according to locals, the normal price at a market would be around 1,5002,000 TZS.), it was left out of the study due to the high degree of inaccuracy. Had this information been available earlier, there would have been time to find other, smaller but also safer, markets around the city, on which a more accurate analysis and compaAnother significant challenge this study fa- rison could be based. ced in Tanzania was the issue of safety. The initial idea has been to visit the Kariakoo This thesis has been a learning process. It Market in the central part of Dar es Salaam, has truly emphasised the importance of because that would give the best idea of remembering who a design is meant for how much money locals could get for their rather than focusing narrowly on the deurban farming crops if they were to sell sign itself. Being faced with a person who them. However, during the visit it became knows his life and home are at risk severapparent that it would not be an option; se- al times a year during rainy seasons really 2

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08-15-18: Tanzania shilling (TZS) to Danish kroner (DKK): 1000 TZS = 2.87 DKK

brings things into perspective and it has made it very clear that the functionality of a design can be just as, if not more, important as the aesthetic element. As a result, this thesis strikes a balance between the two in a way that demonstrates how important it is to not only create isolated solutions, but to consider how different elements of solutions can work together as one integral whole. In this thesis, this is done in a way that tackles problems with erosion while managing to improve livelihood in the affected area. It is simple, sustainable, easy to

establish and maintain, and still manages to provide inhabitants with something of good value.

It is not possible for one single person to stop or prevent climate changes. It is not possible to deal with all the problems these changes produce, but the aim of this project is to help generate new ideas on how to create simple and cheap solutions that can deal with at least some of the problems caused by climate changes.

“For the great doesn’t happen through impulse alone, and is a succession of little things that are brought together.� (van Gogh, 1882)

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PICTURES

Figure 1: Original.

Figure 3: Original.

Figure 5: Original.

Figure 6: http://tropical.theferns.info/image.php?id=Ximenia+caffra, 10-02-2019.

Figure 7: Fryd, O., Backhaus, A., Herslund, L., Adugna, D., Assefa, A., Jensen, M.B., Justin, G., Mguni, P., Mpyanga, S., Workneh, A. and Yeshitela, K. (n.d.). Draft landscape-based stormwater management strategies for the Jemo and Mbezi River catchments, Water Resilient Green Cities in Africa, Report 2, Work package 2.

Figure 8: Original.

Figure 9: Original.

Figure 10: Original Figure 12: Original.

Figure 13: Original.

Figure 14: https://www.livescience.com/44499-how-do-pineapples-grow.html, 01-15-2019.

Figure 15: https://www.frozenseeds.com/products/chinese-jujube-seeds-ziziphus-jujuba, 01-15-2019.

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Figure 16: Original.

Figure 22: https://www.amazon.com/Medjool-Seeds-Phoenix-dactylifera-Mejhool/dp/B 07GNMQDVL, 02-22-2019 Figure 23: https://www.indiamart.com/proddetail/allium-sativum-plant-powder-113455 98373.html, 02-22-2019 Figure 24: https://jerry-coleby-williams.net/2014/05/29/in-production-today-may-2014/ sweetpotato-ipomoea-batatas-marguerite-flowers-1/, 02-22-2019 Figure 25: https://www.videoblocks.com/video/green-bananas-on-banana-tree-plant-rxgebli4qlizrdo58u, 02-22-2019 Figure 26: https://www.mozambiqueflora.com/speciesdata/image-display.php?species_ id=122060&image_id=14, 02-22-2019 Figure 27: https://www.mozambiqueflora.com/speciesdata/image-display.php?species_ id=157800&image_id=4, 02-22-2019 Figure 28: https://flora.org.il/en/plants/DACAEG/, 02-22-2019 Figure 29: https://www.frozenseeds.com/products/chinese-jujube-seeds-ziziphus-jujuba, 02-22-2019 Figure 31: http://swbiodiversity.org/seinet/imagelib/imgdetails.php?imgid=293667, 0222-2019 Figure 32: http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:316944-2, 02-222019

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Figure 33: https://www.plantingman.com/ginger-vegetable-garden/, 02-22-2019 Figure 34: https://www.videoblocks.com/video/green-bananas-on-banana-tree-plant-rxgebli4qlizrdo58u, 02-22-2019 Figure 35: https://www.jircas.affrc.go.jp/project/africa_dojo/FakaraPlants/Contents/Species_pages/Amaraspi.html, 02-22-2019 Figure 36: https://botanyphoto.botanicalgarden.ubc.ca/2017/03/cordyla-africana/, 02-222019 Figure 37: https://calphotos.berkeley.edu/cgi/img_query?enlarge=0000+0000+0107+0231, 02-22-2019 Figure 38: https://www.zambiaflora.com/speciesdata/image-display.php?species_id=137 810&image_id=3, 02-22-2019 Figure 40: http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:12322-2, 02-222019 Figure 41: https://antropocene.it/en/2018/11/11/zea-mays/, 02-22-2019 Figure 42: https://www.gardensonline.com.au/gardenshed/plantfinder/show_929.aspx, 02-22-2019 Figure 43: https://veggiesinfo.com/tag/praecitrullus-fistulosus/, 02-22-2019 Figure 44: https://www.hyphaene.org/index.php/species-and-synonyms/hyphaene-compressa, 02-22-2019

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Figure 45: https://www.farmerstrend.co.ke/muratina-tree/, 02-22-2019 Figure 46: https://www.worldwidefruits.com/coccinia-grandis---ivy-gourd.html, 02-222019 Figure 47: https://cjmgrowers.co.za/englerophytum-natalense/, 02-22-2019 Figure 49: http://hablemosdealimentos.com/c-frutas/el-mango/, 02-22-2019 Figure 50: https://www.polynesia.com/blog/coconut-tree-climbing-samoan-style/, 02-222019 Figure 51: https://www.evergreengrowers.com.au/shop/fruit-and-edible/black-passionfr uit-passiflora-edulis/, 02-22-2019 Figure 52: http://www.tipdisease.com/2014/11/benefits-and-nutrition-of-guava-fruit.htm l, 02-22-2019 Figure 53: https://en.wikipedia.org/wiki/Annona_senegalensis, 02-22-2019 Figure 54: https://www.zambiaflora.com/speciesdata/image-display.php?species_id=1260 80&image_id=1, 02-22-2019 Figure 55: https://www.amazon.in/M-Tech-Mall-Tamarind-Tamarindus-Seedling/dp/ B07J3XP3NF, 02-22-2019 Figure 56: https://www.mozambiqueflora.com/speciesdata/image-display.php?species_ id=140050&image_id=4, 02-22-2019

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Figure 58: http://hablemosdealimentos.com/c-frutas/el-mango/, 02-22-2019 Figure 59: https://commons.wikimedia.org/wiki/File:Azadirachta_Indica.JPG, 02-22-2019 Figure 60: https://herbologymanchester.wordpress.com/tag/oryza-sativa/, 02-22-2019 Figure 61: https://commons.wikimedia.org/wiki/File:Carica_papaya_22_08_2012.JPG, 02-22-2019 Figure 62: https://www.pinterest.co.uk/pin/390546598928484341/, 02-22-2019 Figure 63: https://www.mozambiqueflora.com/speciesdata/image-display.php?species_ id=138900&image_id=6, 02-22-2019 Figure 64: https://www.zambiaflora.com/speciesdata/image-display.php?species_id=1346 20&image_id=2, 02-22-2019 Figure 65: http://www.sunshine-seeds.de/dovyalis-abyssinica-53973p.html?language=en, 02-22-2019 Figure 67: http://hablemosdealimentos.com/c-frutas/el-mango/, 02-22-2019 Figure 68: https://www.thespruce.com/growing-avocado-trees-home-garden-3269412, 02-22-2019 Figure 69: https://herbologymanchester.wordpress.com/tag/oryza-sativa/, 02-22-2019 Figure 70: https://www.planetayurveda.com/library/jamun-syzygium-cumini, 02-22-2019

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Figure 71: http://www.southcoastgrowersflorida.com/reclinata.html, 02-22-2019 Figure 72: http://phytoimages.siu.edu/imgs/paraman1/r/Clusiaceae_Garcinia_livingstonei_126688.html, 02-22-2019 Figure 73: https://en.wikipedia.org/wiki/Adansonia_digitata, 02-22-2019 Figure 74: https://www.pinterest.dk/pin/575334921132436242/, 02-22-2019 Figure 75: Photo by Lucia Moretti.

Figure 76: Original.

Figure 77: Original.

Figure 78: Original.

Figure 84: Original.

Figure 85: Original.

Figure 88: Original.

Figure 97: Original.

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