Assessment of future water demand in the Umbeluzi river basin in Mozambique

Abstract

The management of water resources in the Umbeluzi River basin is an important issue due to the worsening of water scarcity in urban centres and in agriculture, which can jeopardize socio-cultural, ecological, and economic values. Even more important is the fact that it is an international basin, whose demand for water has been increasing due to agricultural expansion, population growth and possible failures in the integrated management of water resources. The study evaluated the allocation of surface water to meet different needs using Water Evaluation And Planning (WEAP) model.  WEAP model was validated in the period from 2005 to 2011 with NSE of 0.69 and Bias of 5.2% in the volume of the reservoir and 2005 with an NSE of 6.7 and Bias of 6.0% in the flow. Four scenarios were evaluated taking into account the domestic, agricultural and industrial sectors. The results show that the unmet demand is 33.6 hm3 and 57.3 hm3 in domestic supply and 3.5 hm3 and 7.4 hm3 in industry for the Reference and Highest Growth scenarios in 2040. In agriculture, unmet demand is estimated at 12.9 hm3 and 22 hm3 in 2040. These results emphasize the need to implement demand-side management strategies to minimize the impacts of water scarcity.