Mapping Representation of Gully Erosion in The Al-Sijr Valley Basin, South of Al-Najaf Governorate, Using the Bergsma Model and Geographic Information System (GIS) Data

Abstract

This study applies the Bergsma model within a Geographic Information System (GIS) framework to assess the magnitude of gully erosion in the Al-Sijr Valley Basin, southern Al-Najaf Governorate, Iraq, covering an area of approximately 188.14 km². The analysis integrates Landsat 9 satellite imagery, a 30 m-resolution Digital Elevation Model (DEM), and specialized software packages (ArcGIS 10.8, PCI Geomatica 18, and RockWorks 17) to generate a detailed cartographic representation of erosion patterns and evaluate the natural factors influencing erosion severity. Five gully erosion classes were identified, ranging from slight (Class 1) to very severe (Class 5). Results indicate that severe erosion predominates, affecting 155.6 km² (82.7%) of the basin’s total area. These findings underscore the urgent need for targeted environmental management strategies, proactive land-use planning, and coordinated decision-making to mitigate ongoing land degradation and prevent further soil loss in the basin.

The region's steep slope, aridity, and sparse vegetation cover contribute to high gully erosion activity, making it highly responsive to even the weakest rainstorms. The lengths of the gully eroded in the Wadi Al-Sijr basin vary, ranging from 98.3 to 15823.5 meters, which is reflected in the spatial distribution of erosion. The Wadi Al-Sijr basin is subject to gully erosion, with the most extensive erosion cover an area of ​​155.6 km², representing 82.7% of the basin. The Bergsma model is an effective method for estimating the extent of erosion in arid basins.