Mapping groundwater availability and adequacy in the Lower Zambezi River basin

Abstract

Groundwater plays an important role as a source of water for various socio-economic uses and environmental requirements in the lower Zambezi basin in Mozambique. Hence it is important to know its availability and adequacy in space to inform decision making for sustainable water management practices. For a derivation of a Groundwater Availability map and a Groundwater Adequacy map we adapted the DRASTIC methodology in a GIS environment to determine how different parameters, such as precipitation, topography, soil drainage, land use and vegetation cover, aquifer characteristics and groundwater quality affect (i) groundwater recharge on a long-term sustainable basis, (ii) the short-term abstraction potential and (iii) the long-term adequacy of groundwater utilization for domestic use. Results showed that groundwater availability in the Zambezi basin varies mostly from medium to low, with highest potential along the perennial rivers and in the delta where it plays a crucial role in environmental preservation. The southern margin of the Zambezi River shows low groundwater availability and also presents low adequacy for domestic use due to poor groundwater quality. The results from this study will be used in determining the most promising future development pathways and select the most attractive strategic development plans of the Mozambican government for the Lower Zambezi basin.