Preparation of Curve Number Grid Map of Rawanduz River Basin in KRI Using GIS Techniques

Abstract

The study is being conducted with the goal of applying various models and techniques for catchment
delineation and providing the opportunity to determine the Curve Numbers (CN) for the Rawanduz
river basin (2956 Km2
), which is located in the northeastern section of Iraq, Kurdistan region, by
utilizing Geographic Information System (GIS). Satellite data (Landsat 8 OLI) for 2020 was utilized to
build land cover classes, with a classification accuracy of 90% and a Kappa index of 86.18%. The
hydrologic soil map for the region is digitized from the Iraqi soil map. In specifically, Soil Conservation
Service-Curve Number (SCS-CN) is technique that will be utilized to predict direct surface runoff. This
technique incorporates a range of significant watershed features, such as Hydrological Soil Groups
(HSG) and land use/land cover (LU/LC), to be utilized as input variables for numerous hydrologic
processes. In terms of land use and hydrologic soil group combination, the lowest CN value was found
to be 58 in forest areas, which corresponds to an increased ability of the soil to retain rainfall and will
produce much less runoff, and the highest CN value was found to be 92 in medium-residential areas,
which causes most of the rainfall to appear as runoff, with minimal losses.