Findings
To summarize our case study of SUDS applicability in informal settlements, we documented in a report, “guidebook”, and website key findings, including both the physical and social conditions that arose as a result of stormwater management issues. Below we discuss major results and findings from each of our four main objectives.
IDENTIFYING AND CATEGORIZING FLOODING AREAS
Our first objective was identifying and categorizing flooding areas along the road. We accomplished this by identifying the different types of flooding conditions and the contributory factors that perpetuate said conditions. We have categorized three main factors that contribute to current flooding conditions along the road. The three categorizations include: 1) Taps 2) Toilets and 3) Road Topography; and a description of and how each category contributes to the flooding conditions follows:
TAPS –Houses located near taps (abused by residents) have an increased chance of suffering from flooding. The flooding is not severe, but can lead to problems such as health hazards and distress of the residents.
TOILETS – Communal toilets leak due to a lack of proper, routine maintenance and emptying of conservancy tanks. Health hazards are created as waste water pools in roads and near houses.
ROAD TOPOGRAPHY – Conditions inherent to the natural and human influenced topography of the road can contribute to and augment flooding in areas along the road. The team has further delineated this categorization into four designations or subcategories: 1) Gentle or Steep Slopes 2) Winding Roads 3) Divots and 4) Low-lying Valleys. A description of how each of these subcategories contributes to the road topography and its affect on flooding follows:
1. Gentle or Steep Slopes – Depending on the gradient of the slopes in the road, the flooding can be characterized in a variety of ways. Steep gradients cause faster water runoff and create greater potential for infrastructure damage. Gentle slopes result in slower movement of water, but result in pooling of water.
2. Winding Roads – Bending roads frequently result in the disruption of the natural flow of water. The water won’t flow along the road and will flood into the houses.
3. Divots – Irregularities in the road can cause problems during rainstorms, as the water flow becomes erratic due to the divots. It changes course and flows into residents’ houses and accumulates and becomes stagnant.
4. Low-lying Valleys – The natural landscape of Monwabisi Park poses a flood risk, since water naturally flows with gravity to the lowest point possible (this area).
ANALYZING THE IMPACT OF FLOODING
Our second objective was analyzing the impact of flooding. This analysis included a consideration of the overall impact of flooding within Monwabisi Park as well as the deeper physical and social impacts associated with flooding, which are entrenched within the settlement. Results of these considerations are shared below:
OVERALL: PREVALENT, BUT NOT LONG-LASTING, VARIABLE, EPISODIC, NOT AS SEVERE AS OTHER SETTLEMENTS (CAPE FLATS)
Initially, 17 areas were identified as prime flooding spots, and through interviews, these areas were narrowed down to 4. Flooding has been described as prevalent, but not long-lasting. In Monwabisi Park, it has been identified as a problem, but it is only episodic in nature, when compared with other settlements, specifically in the Cape Flats.
PHYSICAL: SOME INFRASTRUCTURAL DAMAGE, EROSION OF THE ROAD, POOLING OF WATER.
Flooding has specific physical consequences, such as erosion of the road resulting in movement of sand from one location to another. The shifting of sand allows water to seep into homes along the road. Pooling of water also results in flooding due to sand becoming oversaturated, leading to the runoff water spreading to low-lying areas.
SOCIAL: CAN CREATE COHESION OR TENSION (MORE TENSION), HEALTH HAZARDS, DISTRESSING
Many areas have a high prevalence of tension resulting from stormwater problems, witnessed to lead to a high level of distress among residents. Pooling of water, and its mixture with grey and black water, creates significant health hazards in various areas as well.
DETERMINING CURRENT RESPONSES TO FLOODING
Our third objective was determining current responses to the flooding issues and conditions we identified and how these interventions contributed to the physical and social impacts we analyzed. A chart of the physical interventions currently employed by the residents has been included below. For organizational purposes and in order to orient the reader, we have shared a bulleted summary- illustrating the observations the team has gathered regarding current interventions- preceding the chart of physical interventions. The chart itself is followed by a specific description of each intervention and an overview of the social reactions to the use of said interventions (detailed information following objective four).
SUMMARY:
Many stormwater techniques are already in place and used by the local residents. These include fences, tyres, culverts, vegetation, accumulation of sand, wooden ledges/boards, raised platforms, and plastic. The majority of these techniques are widespread throughout the settlement, while other interventions which are more complicated to design, like raised platforms and plastics, are less commonly used by the residents.
Interventions found within Monwabisi Park serve to do three main things; create a barrier against the water, create a path of redirection for the water, and assist in the absorption of water into the ground. These three functions can all help minimize flooding in one aspect or another, but the manner in which they do this varies depending on the size, location and effectiveness of the system.
The effectiveness of informal stormwater interventions varies widely, both by intervention type and the intention of specific applications. These depend on factors such as whether the underlying strategy of the technique is intended to prevent flooding, what level of maintenance it entails (on both a long-term and short-term basis), and what extent of construction it requires. If the intervention is relatively simple to design and install, such as the stacking of tyres or the creation of ditches, then the chance of it being built correctly and effectively is higher than if it entails a greater amount of assistance to set up.
Socially, existing interventions cause numerous problems within the community. Techniques beneficial to one resident often negatively affect others, and residents expressed emotions ranging from subtle annoyance to vociferous frustration, resulting in distress and lack of trust. Our SUDS-informed recommendations to encourage cooperation among neighbours are designed to reduce these problems, and to assist in creating solutions that can benefit a large group of people all at the same time.
DETERMINING APPROPRIATE RESPONSES TO FLOODING ISSUES
Our fourth and last objective was determining appropriate responses to the flooding issues and conditions we identified and to the physical and social impacts we analyzed. We considered the interventions currently used and sought to create models for proposed solutions which incorporate SUDS and adapt it to informal settlements. A discussion of our findings follows:
The implementation of SUDS in informal settlements requires much preparation in order to identify all of the technical, institutional, economical, and social factors that may affect the development objectives of the proposed systems. Land constraints and potential interferences caused by preexisting conditions and systems need to be recognized before beginning the project, so that resources can be mapped out and the overall cost can be minimized to the greatest extent (Micou, 2006). A series of oral surveys and field studies can aid not only in the identification of these physical restraints, but also in the generation of maps that lay out which areas are suitable for new drainage systems and methods. These maps can take into account the topography of the area by looking at the varying depressions and elevations. Upon review, an analysis of these land features can determine which areas will be able to successfully accommodate specific methods and systems. Due to the low-income environment within informal settlements, these restrictions are crucial to the implementation of the project. If they are not correctly defined, the proposed costs could be too high and the sustainability of the proposed systems could be negatively affected.
In Monwabisi Park, the preventative measures that the residents have implemented are only partially successful. To help increase the effectiveness of stormwater management plans in an informal setting and to work alongside these interventions, we proposed four different SUDS methods that we have adapted to work in an informal settlement. These solutions included artificial swales, soakaways, infiltration trenches, and a wetland. One main philosophy behind SUDS interventions is obtaining community involvement. By encouraging collaboration among community members, it is possible to create a plan that can benefit a larger group of people. By promoting community-wide efforts and teamwork, the management demands, which are greater than the demands of the current interventions, will become more reasonable and easier to satisfy.
Chart of Physical Interventions:
Physical interventions- Some of the current interventions present along the studied road included: fences; culverts and holes; accumulation of sand bordering the sides of the roads; vegetation; wooden boards and ledges; tyres. The functionality of these methods and techniques vary greatly, as summarized below.
Fences:
Fences serve as a barrier against both rainwater and communal tap water runoff and are designed to prevent household flooding. They are built around the perimeter of individual yards and are often incorporated with other interventions to reinforce their stability and functionality. Due to them being built directly into the sandy ground, over time they sink into the sand and become lowered.
Key Features: Varied Materials
Thin boards of wood are used commonly as poles to hold the fences up, while the materials that hold these poles together vary from house to house. Some use strands of wire to hold the wood together, while others use scrap pieces of metal siding to keep the poles standing. With regards to stormwater management, the fences that are the most successful in preventing water from entering yards and houses are the ones that are metal. They create a barrier against the water, and help to redirect it around the yard. However, it usually directs it into another nearby, neighbouring yard.
Shadecloths, large pieces of material with a dark green tint that serve to help block the sun and provide privacy to residents, are another resource used in fences. Shadecloths are commonly not used as a method of stormwater management, but some people do consider this technique, and claim that it does help to create a small barrier against the water. In most cases it allows water to enter yards, but it helps to slow the overall flow of water.
Tyres:
When incorporated with the sand found along the road, tyres can be very useful in producing a stable road surface that is able to withstand the pressures of water runoff. Tyres are used to stabilize the sand and prevent it from moving and shifting during a rain storm. They can also be used to form a barrier against water by being stacked on top of one another, ultimately forming a wall-like structure that is similar to a fence.
Key Features: Incorporation with Sand
Burying the tires into the sand stabilizes the sand limiting the creation of unwanted natural paths and channels that redirects water into houses. Stacked designs allow the tyres to form a barrier against the water, and the sand inside of the tyres creates a sturdier base for the tyres to stand upon. Without the sand in the tyres, they would not be strong enough to redirect the water, as the flow would be too powerful for the tyres to withstand.
Culverts:
Culverts (ditches) can be found bordering yards and alongside the road to help redirect water away from houses and into a communal area where no one currently resides. Some of these culverts work very well, as they are built along a sloped area, allowing them to work with gravity to aid the proper direction of water. However, there have also been culverts dug along the perimeters of various residents’ yards that redirect the water into the yards of neighbouring residents.
Key Features: Varied Size
Culverts are adaptable to different conditions, and can be created in numerous, varying areas. Some culverts are approximately a half meter in width, and are commonly found alongside the road, while other ditches are only a quarter of a meter wide and are found in smaller, narrower areas (between houses, along yards). The ability of these interventions to vary in size allows them to be used very commonly by residents who live in different areas and in different conditions.
Vegetation:
Grassy areas are commonly located alongside the road, and bordering the fronts of residents’ yards. They serve to help catch excess water and redirect it to various places both on and off the road. Shrubs frequently resemble a small fence, but they have much greater open space throughout them, which allows water to easily flow through.
Key Features: Grass and Shrubs
The most common grass found in this area is referred to as Buffalo Grass (S. secundatum), which is indigenous to Cape Town. This grass is found sporadically alongside the road and throughout residents’ yards. Unfortunately, the grass is not well maintained, so there are only a few prominent strips, while the rest is found in small patches.
Shrubs are often placed along the border between yards and the road, and they serve to provide a barrier against water runoff as well as to provide privacy and isolation to many residents.
Accumulation of Sand:
Many residents strategically pile sand along the perimeter of their yard and at the base of their house to create a barrier against runoff. The accumulation of sand along the perimeter of yards is commonly incorporated into an existing fence to cover up any holes and to stabilize the fence. Piling sand around the base of a house also serves to reinforce the foundation, and provide a shield between the water and the walls of the house. This helps to keep water from coming in contact with the house, eliminating the amount of water damage seen by floors and furniture.
Key Features: Temporary Nature of Sand Piling
The use of sand as a preventative method against stormwater is often seen as counterproductive. The buildup of sand is much stronger than loose sand found within the road, but it is still not strong enough to form a barrier against powerful stormwater flow. Over time, the sand begins to shift, and the barrier that the residents had formed with it eventually breaks down and begins to allow water to penetrate. Thus, sand barriers require continual upkeep.
Wooden Ledges/Boards:
These ledges are made from long, thin scraps of wood and are positioned either along the perimeter of yards, or directly in front of doorways. They serve not only to block water from entering the unwanted areas (yards and houses), but they also assist in redirecting water into either neighbouring yards or central areas where water accumulates and pools.
Key Features: Permanency
Wooden ledges and boards are built securely into the ground, so that they are able to stand upright and endure the forces of water witnessed during the heavy rain seasons. Due to these slabs of wood being positioned deeply into the ground, they are often hard to remove. This is often seen as an added benefit, because they do not need to be replaced after each rainstorm. Unfortunately, some see this permanency as an obstacle and problem. If the ledge is not working properly, or it was placed in the wrong area, the time and labour that must go into removing and relocating it is sometimes excessive.
Raised Platforms:
Raised platforms are found at the bottom of hills and in low-lying areas, where flooding is the most prominent. The raised platforms incorporate scrap pieces of wood found throughout the settlement to create a border along the entirety of the yards, enclosing an area of excess sand. The risk of flooding is highly decreased due to the entire house being raised above the ground.
Key Features: Permanency and aesthetic appeal
Similar to wooden ledges and boards, raised platforms are long lasting. They are often time consuming to initially implement, but once in place, they are very hard to remove. The boards primarily act as a support to keep the sand in one area, but after the first rainfall, the sand becomes saturated and compacted, creating a firm and sturdy layer.
Even though they are not frequent in this area, the raised platforms that have been built are often well maintained and cared for. Many residents who put the time and effort into implementing and maintaining a raised platform often incorporate other aspects of design into their overall intervention, such as vegetation and shrubs.
Plastic:
Plastic is used to help stabilize sand and protect houses from coming in direct contact with water. The plastic is intended to create a barrier between the sand and the walls of the houses, to eliminate the amount of damage caused by stormwater. It can be located either between a layer of built up sand and the outside walls of a house, or it can be placed between the outside walls and inside walls. When placed between the sand and walls, the primary purpose of the plastic is to stabilize the sand and assist in preventing it from shifting around and breaking down around the houses. When located on the inner portion of the houses, the plastic serves to block the water from entering.
Key Features: Thickness
Plastics range from thin, garbage bag-type consistency, to thick, unbendable forms of plastic that are commonly used in high-strength industrial products. The thick plastics perform better overtime when it comes to forming a steady, reliable barrier against water, but they are often more expensive and harder to find. The thin plastics are much more assessable, and they are consistently less expensive. Unfortunately, these plastics tend to disintegrate with time, and they begin to break down, preventing them from creating a sturdy, reliable barrier.
Social reactions
Socially, it was noted that in hot spots A and D, there was relatively low tension between the neighbours and they were willing to work together to create a community-wide stormwater management system that would have the potential to benefit many people. Specifically in hot spot D, the residents had developed a small water redirection system along the road that resembled a ditch. They created this system by working together in a large group, sharing tools and other resources, and by organizing a collaborative effort to ensure that it was properly implemented. Unfortunately, this willingness to work together was not present in either hot spot B or C. The residents in these areas experienced conflict with one another and were not as eager to work as a collaborative community to design a new stormwater management plan.