HYDRO-GEOPHYSICAL ASSESSMENT OF GROUNDWATER POTENTIAL FOR IRRIGATED-AGRICULTURE IN THE SAWLA TUNA KALBA DISTRICT OF SAVANNAH REGION, GHANA.

Abstract

Despite Africa having huge groundwater potential, we are still behind in terms of groundwater irrigated agriculture. The main objective of this study is to appraise the groundwater potential in the Sawla Tuna Kalba District for irrigated agriculture. The Schoeller equation was used to estimate the groundwater storage and extractable storage within the basin. Hargreaves equation and remote sensing data from November to February (planting to maturity) in the year 2020 for tomato and maize were used to determine the total crop water requirements (CWR) using the extractable growth storage. Moreover, the Geographic Information System (GIS) was used to develop a groundwater potential map of the study area and however, used to create a groundwater quality suitability map for irrigation. Results from the hydro-geophysical survey show that the study area is predominantly underlined by the Precambrian and Paleozoic units. The groundwater storage and extractable storage were found to be approximately 2.4 × 106 Km3 and 9.8 × 106 Km3 respectively. The total Irrigation Water Requirements (IR) for a hectare of tomato and maize were 5,097 m3 /ha/growing season and 5960 m3 /ha/growing season respectively. The total land area available for agricultural use was computed to be around 1282.7 Km2 (128,270 hectares), but the total area that can be irrigated with tomato and maize using groundwater was found to be 143.6 Km2 (14,360 ha) and 196.2 Km2 (19,620 ha) respectively. The groundwater suitability map showed that areas of excellent quality for irrigation had an area of 507.88 Km2 , areas of very good quality were found to be 3277.99 Km2 , good areas was about 790.21 Km2 , less restricted areas was around 24.21 Km2 and areas of that are extremely restricted had area of 1.11 Km2 . Moving forward, an indepth geophysical survey should be conducted to determine the nature of aquifer which can be the basis of any hydrogeological study.