Hydrological Simulation of Surface Runoff in the Wadi Al-Raml Basin Using Snyder’s Synthetic Unit Hydrograph

Abstract

Numerous studies have addressed the utilization of Snyder’s Synthetic Unit Hydrograph model to determine runoff values, as this model relies on employing time coefficients that aid in evaluating morphometric characteristics. Remote Sensing (RS) and Geographic Information Systems (GIS) techniques facilitate the analysis of satellite imagery and the extraction of spatial parameters from Digital Elevation Models (DEM). In this research, a 30-meter resolution DEM was acquired for the Wadi Al-Ramil watershed, which extends from the Al-Garabulli region in the north to the Tarhuna mountains in the south. Analysis within the ArcMap10.8 environment revealed that the elevation of the area ranges from 1 to 514 meters above sea level. Furthermore, the total area of the Wadi Al-Ramil basin reached 442.95 km², with a main channel length of approximately 53.05 km. The hydrological response of the basin varies significantly the average lag time (T_p) was estimated at 9.78 hours, while the average time base (T_b) for floods was around 39.14 hours. The potential annual runoff volume in the basin was estimated at an average of 8.96 million m³ with a peak discharge intensity ranging between 49.39 m³/s, and 112.85 m³/s. The findings of this research confirm the existence of real hazards manifested in soil erosion and channel bank degradation, which have led to vegetative cover depletion and the loss of some forests surrounding the wadi.