Geospatial Assessment of The Potentials of Rooftop Rainwater Harvest at The Federal University of Technology, Akure, Nigeria

Abstract

Recent reports reveal water shortage at the Federal University of Technology, Akure, (FUTA), Nigeria, with possibilities to worsen if adequate measures are not taken. This research focuses on the assessment of the potential of an alternative source of water supply the Roof Top Rainwater Harvest (RTRWH) at FUTA. This study goes beyond the determination of the potential volume of RTRWH by proposing a storage plan for the RTRWH based on geospatial analysis. Data collected for the study are rainfall data covering 19 years (2000-2018), High-Resolution Satellite Image (HRSI), Ground Control Point (GCP), attribute data, Landsat 8 and Shuttle Radar Topographic Mission (SRTM) Digital Elevation Model (DEM). The rooftop areas were extracted by processing HRSI using ArcGIS software. The volumes of the RTRWH for each building were computed with the rooftop area, precipitation amount and roof's runoff coefficient of the rooftop material as variables. Suitable locations for siting the storage tanks were proposed based on Multi-Criteria Decision Making (MCDM) and geospatial analysis. Result obtained from the study reveals that the total area of rooftop catchment for all buildings considered is 164,246 m2. The study suggests 9 locations suitable for collecting and storing the harvested RTRW. The potential average daily, average monthly and total annual volumes of RTRWH are approximately 607 m3, 18,473 m3 and 221,681 m3 respectively, and thereby could potentially provide ~ 41% of water demand in addition to the existing water supply sources in FUTA. The RTRWH is therefore recommended as an alternative water source at FUTA.