Effectiveness of Rainwater Harvesting as a Strategy For Flood Mitigation in Ruai Area, Nairobi County, Kenya.

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Nkirote, Doris
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Kenyatta University
Harvesting of rainwater is a strategy which primarily benefits the local human livelihoods and ecosystems. Ruai has gone through development boom and densitification, increased infrastructure such as roads, both single and multi dwellings leading to changes in the physical characteristic of the area hence increased surface run-off. Further Ruai and its environs are flat hence encouraging flooding .There has been a range of incidences of flooding in the area causing loss of property, disruption of socio amenities such as schools, hospitals and roads. Structural measures such as drainage ditches, infiltration trenches have been advanced and used to reduce flooding effects during rainy seasons.. However, these measures have not been effective due to large population growth and increased infrastructure in Nairobi. This study investigated rainwater harvesting effectiveness in Ruai as an effective method of flood mitigation and control. The objectives achieved were to evaluate the socio-economic effects of floods in Ruai area, to examine strategies used by the households and community and their success in avoiding loss and damage from floods in Ruai area, to assess household‘s RWH adoption and farmingrelated uses in Ruai, to find out the socio-economic determinants of RWH adoption and to assess RWH‘s impact on flood mitigation in Ruai. Using a descriptive research design the study sampled 99 house hold heads and 6 key informants through purposive sampling. The study employed questionnaires for households and interview schedules for key informants. The household questionnaire survey generated both descriptive and numeric information. Closed questionnaires generated quantitative data, whose presentation and analysis entailed tabulation in terms of and other techniques such as frequencies, percentages and the mean. Interviews and open-ended questionnaires helped gather qualitative data that was analysed through coding and classifying (categorising and indexing). The results indicated that floods led to destruction of property, disruption of social amenities, water borne diseases, with 56 of 94 respondents migrating to higher areas at Ruai during floods. Structural drainage systems such as dykes and culverts were used in controlling floods with only a third of the respondents using rainwater harvesting as a strategy to control floods. Socio-economic factors such as gender, age, household size, education level, income level and land ownership determined the adoption of water harvesting in a bid to control floods. More than 60% of the respondents indicated that rainwater harvesting reduced lag time for storm formation while 86% showed a reduction in overland flow. The study recommends the need for all the stakeholders in Ruai and Nairobi County to seek Rainwater harvesting strategies in ending the perennial flood problem. Rainwater harvesting is a strategy that if well instituted and implemented can help reduce and mitigate floods in Ruai and be an alternative during water scarcity period. Community awareness should be done to encourage households to think of and embrace rainwater harvesting as a strategy for flood prevention and mitigation and not only to capture water for domestic use.
A Thesis Submitted in Partial Fulfilment for the Degree of Master of Environmental Studies (Community Development) in the School of Environmental Studies of Kenyatta University
Rainwater Harvesting, Flood Mitigation, Ruai Area, Nairobi County, Kenya