Morphometric Characteristics and Flooding Risk of Zhrzy Valley in the Rania Plain, Northern Iraq

Employing GIS alongside multi-criteria analysis for morphometric and flood risk mapping is an efficient method to pinpoint areas susceptible to flooding. This method helps water resource planners and decision-makers pinpoint specific regions for detailed flood risk assessments using hydrological and hydraulic models, minimizes resource demands while ensuring precision. The Wadi Zhrzy basin is located in the Rania Plain area in the Sulaymaniyah Governorate, northeastern Iraq. All river levels converge into the main valley course, with the basin containing 796 streams across five levels, totaling 952.87 km in length. The number of stream levels increases with the basin area, and variations in valley levels are associated with differences in valley sizes. The rise in secondary valleys correlates with basin size, with variations influenced by the hardness of rock formations and tectonic activity, affecting fluvial erosion and waterway efficiency. The bifurcation ratio, which reflects water discharge control in rivers, is a key drainage network characteristic. A higher bifurcation ratio, such as 4.234 in this case, indicates increased flood risk and discharge, highlighting geological and climatic consistency within the basin. The river frequency is 1.4318 valleys per square kilometer, and the cutting rate is 6.9056, attributed to the extensive basin area and numerous waterways. The drainage density, influenced by climatic factors like rainfall and temperature, is 1.71399, indicating erosion and carving by waterways. The basin's drainage pattern transitions from dendritic to parallel dendritic. The results indicated that the eastern part of the study area, as well as some western regions, are at high risk of flooding. This outcome aligns with precipitation patterns, slope degree, proximity to streams, and the nature of land cover characteristics. The study highlights GIS and multi-criteria analysis as cost-efficient tools for identifying flood-prone areas. In the Wadi Zhrzy basin, significant flood risks are noted, especially in the eastern and some western regions, due to local topography, precipitation, and land cover. Recommendations include targeted hydrological and hydraulic evaluations, sustainable land management, and improved drainage infrastructure to mitigate severe flooding.