Gully Erosion in Zahlan Township, Sulaymaniyah Governorate

Abstract

This research investigates the levels of gully erosion and identifies its spatial risk in Zahlan Township, Sulaymaniyah Governorate. The intensity of gully erosion was measured based on Bergsma’s (1983) equation. To design a gully erosion intensity map, the study area was divided into squares according to the density of the drainage network derived from a Digital Elevation Model (DEM) with dimensions of 1 km². Each square was numbered and the lengths of gullies within were measured, then multiplied by the map scale using ArcGIS to convert centimeters into meters. The total length of watercourses in each square was divided by its area to determine erosion categories and their spatial extent. Based on the classification of erosion degrees according to Bergsma’s method, the region was divided into four erosion zones and further classified into five categories of gully erosion. Results show that the second largest portion of the study area lies within hill slopes, which have been subject to increased soil stripping and rainfall-induced erosion. These slopes, with an area of 53 km² (26% of the district), revealed high gully erosion activity. The findings highlight the geomorphological risks associated with erosion processes in Zahlan Township and emphasize the importance of monitoring land degradation in sloping areas.