Optimal Surface Water Resources Allocation Using Water Evaluation and Planning (WEAP) Model: The Case Study of Gojjeb River Catchment

Abstract

Water resources scarcity has become one of the determinants which restricts social and economic sustainable development. Improving water use efficiency by means of optimizing water resources allocation nowadays has been considered as the fundamental method for solving water scarcity in river basin. Therefore, water allocation decisions that consider equity, efficiency, and sustainability in every water sector should be treated as the main goal of decision-makers in the river basin. The objective of the research is to model surface water resource of Gojjeb river catchment for optimal surface water allocation and to propose water resource management strategies in a sustainable manner for social, economic and environmental benefits. The WEAP model has been used throughout the world to analyze a diverse set of water management issues for small communities and large managed watersheds, therefore for this study Water Evaluation and Planning (WEAP) model was used to model the current situation of water supply and demands and also to create scenarios for future water demands and supply. All the required data by the model was collected from different sources and the model was set up for a current account year in 2017 and the scenarios persists in 2045 based on the available data. The water resources system of the area were modeled and evaluated while giving consideration for existing developments in relation to current and future water demands among multiple water users in the catchment. Water demand was simulated for three different sectors, domestic, livestock and agriculture. The result from the current situation of water demands among water users were indicated that all demands were satisfied fully and there was no unmet demand under the base year (2017). Currently the catchment has the surface water availability of 2.01BCM. Three scenarios for future water demand were created namely reference scenario, scenario one and scenario two. The results of scenarios one and two were 48.57MCM and 58.51MCM water demands and 1.22MCM and 5.52MCM unmet water demands. The results of these scenario showed that the increment of water demands and unmet water demands from year to year due to reduction of crop water requirement, increment of irrigation area and increment of population growth as well increment of consumption rate. Finally further researches on groundwater availability as an alternative water sources to meet the unmet water demands were suggested.