Developing flood resilience for Kyabamba watershed in Kisiizi through flood water harvesting technology

Abstract

Flooding is the second natural disaster that affects numerous communities worldwide, causing substantial damage to infrastructure, livelihoods, and human lives. Globally, floods have recently become rampant which many writers have attributed to climate change as a result of increased human activity that produces greenhouse gases. The same factor of climate change poses a threat of increased water scarcity in diverse regions especially the Sub-Saharan African region. For this reason, flood water harvesting technologies have been developed to mitigate adverse impacts of flooding and as well enhance flood resilience. This study thus presents a process taken in Kyabamba Catchment looking at the possibility of employing flood water harvesting technology to bring about flood resilience in the community. In this study, data was collected from different sources and screening done on the rainfall and discharge datasets using the linear scaling percentage bias and linear regression respectively. Kyabamba Catchment being ungauged, physical similarity regionalization was done with Mitano Catchment as the donor. Rainfall frequency analysis with the aid of HEC-SSP 2.3, Hydrologic modeling with HEC-HMS 4.11 and continuous calibration for Mitano Catchment was done and parameters transferred to Kyabamba Catchment. Through 2-D hydrodynamic modeling using HEC-RAS 6.4.1 and Vulnerability analysis using spatial multicriterial Evaluation, flood risk assessment of Kyabamba Catchment was established. Potential flood water harvesting technologies that is to say Spate irrigation and recession farming, underground tank, valley dam, and surface reservoir were identified and a socio hydrologic approach with the help of a questionnaire was adopted to determine the most suitable technology. SPSS was used to evaluate the questionnaire and analyze the data. Information generated suggested a surface reservoir for the outcompeting technology however the local community of Kisiizi admitted to no water scarcity being rich with springs that continually flow from the hills. However, the neighboring communities of Kisiizi experience water scarcity being at a distance from the sources of water. A retarding Basin with a broad crested weir was designed on one reach and this caused a flood reduction of 11.1%.