Identifying Flooding Hot Spots Method

Identifying Flooding Hot Spots: (Return to “Mission and Philosophy”)

On the first day of work in Monwabisi Park, we, the stormwater management team, accompanied by co-researchers, walked along the two pilot roads designated by the VPUU: one within B-section and another within C-section. For the first week, we conducted preliminary interviews with people who lived on both roads, focusing on the effects of stormwater during heavy rain periods. Based on the resident responses, and with the direction of Dr. Kevin Winter, we concluded that the pilot road in C-section (Figure 1.1) had a greater need for the implementation of a stormwater management system, as more residents experienced greater amounts of flooding along that road. The C-Section road started at the main road, Mew Way, and ended by the VPUU kick-about (soccer field).

Figure 1.1: C-Section Road

We walked along the C-section road again, this time with Dr. Winter, and focused on the various conditions of the road. These conditions included the topography and composition of the road, density of houses on either side of the road, path of the road, which included the bends and key side roads, and lastly, the existing stormwater interventions. The topography of the road varied significantly in different sections, with gradients differing by a few meters, which created valleys that contributed to the pooling of stormwater. The road was mostly made up of sand with rocks embedded in it, and as we had learned throughout our previous research, in environments such as this, sand tends to move around and shift easily to create divots, causing unfavorable road conditions. As seen in the map (Figure 1.1), the road has one major bend about 50 meters from the start of the road, putting the shacks in that area at a higher risk for flooding.

Using these conditions, Dr. Winter and ourselves identified seventeen different spots on the road that could potentially have been affected by stormwater. Using a portable Global Positioning System (GPS), we marked these spots on a map obtained from a software program, Google Earth, and used them as a guideline to interview residents of these areas. We conducted a more formal interview composed of questions we had prepared which helped to pinpoint problems focused specifically on flooding. At the end of the week, we decided to narrow down the number of hot spots to four major hot spots that experienced the greatest amount of flooding and showed the greatest potential for improvement (Figure 1.2).

Figure 1.2: Identified Hot Spots

Hot spot A is located at the bend in the road (Figure 1.2), and experiences flooding due to the downhill slope and the uneven surface of the ground. The houses located directly on the bend of the road experience flooding because the water flows directly towards them. Hot spot B is located at a valley in the road where both sides of the road slope down into a low-lying area surrounded by houses at the bottom. This causes stormwater to flow directly into the houses and pool at the very bottom of the hills. Hot spot C is located at the bottom of a downhill slope, but the major problem in this area is the flow of greywater created by the toilets and communal water tap. The stormwater mixes with the greywater and creates unfavorable conditions for the residents who live in this region. Hot Spot D is located at the end of the road, which is also at the base of a downhill slope. This section is very important because there is an area behind the houses that could potentially be used as a location for a wetland. Analysis of these different hot spots assisted us in determining appropriate stormwater management solutions for these areas that we can also suggest to be used in other regions of Monwabisi Park that are comprised of similar conditions.

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