Groundwater recharge in Molepolole area, SE Botswana

Abstract

Groundwater recharge estimation using chloride mass balance (CMB) method was conducted in Molepolole area, SE of Botswana. The study area is semi-arid area with uneven distribution of rainfall throughout the year. The mean annual rainfall of the area is 423.64 mm. Climatically the area is characterized by two rainy seasons during the year separated into two by dry months. The first rainy season occurs during January, February, March and April and contributes 55.08 % of the mean annual rainfall of the area. The five months in the dry season are May, June, July, August and September and contribute 5.98 % of the mean annual rainfall of the area. October, November and December constitute the second rainy season and contribute 38.94 % of the mean annual rainfall of the area. The main source of groundwater recharge is rainfall. The computed groundwater recharge in the area is 0.82%, 3.14% and 0.09% of the mean annual rainfall of the area during the first rainy season, second rainy season and dry season, respectively.