Optimization of Rainwater-Harvesting Dam Placement in Iraq’s Western Desert: A GIS and Mathematical Modeling Approach

Abstract

This study introduces a novel methodology for optimizing the design of small dams in the Western Desert of Iraq, a region characterized by its vast expanse and significant flood water influx, particularly in the Horan Valley. The approach integrates Geographic Information Systems (GIS) with a custom-developed Visual Basic program, termed the Optimal Height and Location Model (OHALM), to determine the most effective dam height and location. The initial phase of the study involved utilizing GIS to identify potential dam sites in Horan Valley, based on a set of defined criteria. Subsequently, OHALM was employed to ascertain the optimal dam height, taking into account economic factors such as minimal evaporation losses and maximal water storage capacity. The study culminated in the selection of 13 proposed small dam sites, with height estimations ranging between 12.5 to 14 meters, allowing for a total water storage capacity of approximately 303 million cubic meters. This capacity expansion resulted in an increase of the valley's water body area from 15 square kilometers to 90 square kilometers. Comparative analysis of these proposed dam heights with those of existing structures in the valley revealed a relative variance of 10.4% in the upstream, 7.2% in the midstream, and a comparable percentage in the downstream areas. The research highlights the efficacy of integrating GIS and Visual Basic programming for the strategic development of water resource management systems, particularly in arid regions. This innovative approach demonstrates the potential for significant improvements in water storage and management, addressing the critical need for sustainable water resources in arid environments.