Evaluating the impact of plot scale rainwater harvesting on flood risk reduction and water demand in Kampala industrial and business park, Namanve.

Abstract

The Government of Uganda, through the Uganda Investment Authority (UIA), is supporting the development of the Kampala Industrial Business Park (KIBP) located in Namanve, to the west of Kampala However, the Kampala Industrial and Business Park (KIBP) has over time been associated with flooding as a result of high-intensity rainfall often causing stormwater runoff that exceeds the capacity of the current drainage system. The main objective of this project was to develop a physically, rainfall-based model to assess the impact of rainwater harvesting on flood risk reduction of the industrial park In this study, a catchment area of 10.92km2 was delineated for the industrial park using Arcgis Pro, and rooftops consisting of galvanized iron sheets and pitched roof tiles were digitalized using Google earth to obtain the catchment area of 0.6 km2 for rainwater harvesting. Using Personal Computer Stormwater Management Model (PCSWMM) software, a scenario approach was taken when estimating surface runoff in the industrial park. The scenario approach took into consideration the current state of the industrial park as the baseline scenario and the second scenario involved rainwater harvesting using rain barrels. The two scenarios were analyzed and compared in terms of surface runoff to assess the impact of the rain barrels on the reduction of surface runoff. It was found that there was a 38.6% volume reduction in the surface runoff in the industrial park due to rainwater harvesting using the rooftops as catchment areas in the second scenario. The potential collectable water per annum from rainwater harvesting in the industrial park was determined as 199,950m3 and this contributes 30.3% on the water demand