Double Assessment of Dam Sites for Sustainable Hydrological Management Using GIS-Fuzzy Logic and ANFIS: Halabja Water Supply Project Case Study

The Halabja Water Supply Project (HWSP) in northern Iraq, relies predominantly on the Sirwan River for its water supply. However, the new dam constructions upstream on the Sirwan River within Iranian territory have led to a marked decline in water availability, thereby jeopardizing the sustainability of HWSP operations. This research focuses on pinpointing the most strategic location for erecting a new dam to secure a reliable and consistent water supply for the HWSP, mitigating the adverse effects of upstream water management practices. In the initial phase of this study, ArcGIS was employed in conjunction with the Fuzzy gamma overlay method and weights derived from the Fuzzy Analytic Hierarchy Process (FAHP). Several critical factors were evaluated, including rainfall, slope, land use/land cover, drainage density, geology, and proximity to the intake point. Through this comprehensive analysis, it was determined that only 3% of the study area was highly suitable for dam construction. In the second phase, three highly suitable locations—Gryana, Zmkan A, and Zmkan B—were assessed within the identified areas using the Adaptive Neuro-fuzzy Inference System (ANFIS) approach. The evaluation considered reservoir volume, watershed area, peak discharge, dam length, sedimentation, and cost factors. The analysis ultimately identified Zmkan B as the most suitable site for dam construction. The study's novelty is the integrated and multi-faceted approach to dam site selection. This approach addresses the complexities of site selection, integrating additional assessments to ensure the site’s suitability. This methodology offers a robust dam site selection framework which is highly recommended.