WATER RESOURCES MANAGEMENT [N ARID/SEMI-ARID BASINS

Abstract

An effective modeling tool (WRMIASB model) was developed in this research to facilitate performing the water resources management in arid/semi-arid basins. It provides projection of water demands in the basin and compares them against available water supplies and then allows water resources management scenarios to be simulated by answering a wide range of what if? questions. Wadi Surdud in Yemen was selected as a study basin in this research because it is a typical arid/semi-arid basin in Yemen and other hydrologically similar regions. Seven scenarios for water resources management were developed on the basis of the perceived hydrological features and the water management issues in Wadi Surdud. The main decision variables considered in formulating these scenarios are classified into three categories: one category is related to sources of water supply, another category is related to infrastructure and demand management, and last one related to the basin development. Analysis of the simulation results of each scenario are made to assess their benefits and impacts to distinguish between promising options and less attractive ones, and to make comparison among different scenarios. The results of WRMIASB model will enable the decision maker to select the best scenario considering the economic and groundwater sustainability criteria. 7.2 Conclusions The main derived conclusions derived from the development and application of WRMIASB model to the case study basin are as follows: 1. The study suggests the use of the least favourable, but very frequent, 1.25-years rainfall. This conservative water supply will emphasize the lower surface water supplies, less available water for storage, and is linked to the highest groundwater abstractions. Actual yearly rainfall with higher depth makes the model predictions on the conservative side.