Spatial Modeling for Estimating Surface Runoff Volume and Its Flash Flood Hazards in the Zanta Basin, Duhok Governorate Using the SCS-CN Model

Abstract

The study aims to analyze surface runoff and assess hydrological risks in the Zanta Valley Basin located in Duhok Governorate, northern Iraq, using the SCS-CN model to estimate runoff generated by rainfall. Geographic Information Systems (GIS) and a Digital Elevation Model (DEM) with a spatial resolution of 30 m were used, along with annual rainfall data for the period 2000–2024 obtained from the NASA POWER project. The analysis included soil characteristics, geological formations, land cover, and slope to calculate the Curve Number (CN). The results showed that a large portion of the basin falls within the high runoff category due to steep slopes, low-permeability clay soils, and sparse vegetation cover, which increases the likelihood of rapid flash floods. Furthermore, high rainfall events produced runoff volumes exceeding 15 million m³, particularly in areas dominated by clay formations, indicating environmental vulnerability that necessitates the implementation of water harvesting techniques and sustainable resource management practices.