Evaluation of the flood resilience and flood damage assessment for the Ggaba area

Abstract

Ggaba is a parish in the Kampala city suburb located in Makindye division, on the northern shores of Lake Victoria, at the southern tip of the city of Kampala. It is a low-lying area, which is prone to flooding and experiences floods frequently in events of heavy rainfall, with a recent flood in 2019, which lasted over two years and caused destruction of property, displacement of people and increased water-borne diseases in the area. This study focused on conducting a flood resilience and flood damage assessment through the utilization of software and these were ArcGIS 10.8, HEC-HMS, SWMM and excel. ArcGIS 10.8 was used to delineate the catchment, hydrological and hydraulic models for the river catch-ment were developed in HEC-HMS and SWMM respectively. The curve number method was used as the loss method with the Muskingum method adopted as the routing method to simulate runoff from the catchment. We used to excel functions to plot flood depth-damage curves and develop the damage functions. Stream flows were simulated for the different return periods of 10, 25, 50 and 100 years after which we basin model was calibrated and validated in HEC-HMS by using observed stream flow data of from the DWRM, Ministry of Water and Environment. EPA SWMM version 5.2 was used to carry out the hydraulic modelling for the catchment using simulated stream flow results from HEC-HMS 4.8 and the subsequent flood plain maps were developed for each return period. Field surveys using questionnaires were done in order to establish the flood depth damage rela-tionship and to evaluate the flood resilience in the area. Recommendations for further studies that establish a better flood management plan have been made at the end of the report.