Site suitability analysis for selected flood control structures in Apeduru - Apapi Sub-catchment, Awoja catchment

Abstract

Floods are a major threat to the people of Awoja Catchment especially during the El Nino rains. The Government of Uganda through the Ministry of Water and Environment look to set up flood control structures in the near future in the catchment but information of where to locate them lacks. This study was carried out to determine suitable flood control structures and where exactly in the catchment to locate them using Apeduru-Apapi sub-catchment as a case study. Geographic Information System (GIS) tools were used to map flood prone areas in the sub-catchment and then determine suitable sites for flood control structures. This was done using the Multi-Criteria Decision Analysis (MCDA) methods with the help of the Analytical Hierarchy Process (AHP) tool. An in-depth understanding of how the locals in the sub-catchment have managed floods in the past was achieved through interviews with selected people in the sub-catchment that were permanent residents at the time of the study. A map of flood prone areas was obtained and then valley dams determined as the best option for controlling floods in the sub-catchment. A site suitability map for valley dams was then obtained. It was seen that 14.35% and 61.44% of the sub-catchment is extremely prone and prone to flooding respectively. A total of eight extremely suitable sites were obtained in the villages of Guyaguy, Acuru, Obwapesur, Osudio, Oramun, Tumtum and Okwamumwar. With the results of this study, MWE and OPM will know where to locate valley dams with a main objective of controlling floods, reducing on the costs of determining suitable sites through the conventional methods. It is recommended that feasibility studies are done on the sites determined by the study before flood control structures are constructed there. Further research needs to be done to determine suitable sites for channelization as this was ranked the second suitable flood control measure by the study.