Estimating the surface runoff volume of the Al-Manziliyah Valley Basin, northeast of Maysan Governorate, using Remote Sensing and Geographic Information System (RS-GIS) techniques

Abstract

This study aims to estimate the volume of surface runoff for the Al-Manziliyah valley basin, located in the northeastern part of Maysan Governorate. The basin is a seasonal watershed with an area of (398.97) km². The analysis and processing of Digital Elevation Model (DEM) data, extracted from Landsat 8 satellite imagery, were conducted using Geographic Information Systems (GIS) and Remote Sensing (RS) techniques to derive the hydrological characteristics of the basin.To estimate the surface runoff, the study relied on the (SCS-CN) method to determine the soil types and their ability to retain water. The results showed the presence of three soil types (A, B, C).The study revealed that (65.78)% of the basin area has medium permeability, which promotes the generation of surface runoff in a short period following a rainstorm. The maximum surface runoff volume in the basin ranged between (218 and 121) m³ over an area of (217.81) km², with a surface runoff speed of (0.34) m³/second. The time of concentration was found to be 10 hours, a relatively short duration given the size of the basin, which increases the risk of flash floods in the area, particularly following sudden rainfall events characteristic of the region.