Rainwater Harvesting System for Water Supply in a Rural Community in Edo State, Nigeria

Abstract

Water scarcity is still a major problem in many rural communities in Nigeria. In this study, a rain water harvesting system was designed for Ogbekpen, a rural community in Edo state, Nigeria. A conceptual model for rainwater harvesting was developed using the storm water management model (SWMM), Arcmap 10.1 software and daily rainfall data (2000-2016) obtained from the Nigerian Meteorological Agency (NIMET). Runoff, rainfall intensity and change in elevation of three designated catchment zones were taken into consideration. The results revealed that the total amount of rainwater that could be harvested annually (water supply) was 14,314,351.70 L (14,314 m3) from an overall effective rooftop area of 6025.9 m2. This was three times the annual water demand (4,317,965.60 L (4318 m3)), thus demonstrating the capability of the system to meet annual water demand. The required tank capacities for zones 1, 2 and 3 were 870,412.76 L (870 m3), 955,319.4 5L (955 m3) and 788,629.88 L (789 m3) respectively. Comparative physicochemical and microbial analysis of water from rooftops in the three zones and an existing storage well showed that the latter did not comply with drinking water quality guidelines, thus highlighting the importance of a proper conveyance and storage system to improve water quality and availability in the area.