Morphometric Analysis of Wadi Al Majinin Watershed and its Sub Basins Using GIS, Remote Sensing, and WRB Soil Data, Northwest Libya

Abstract

This study presents a comprehensive morphometric characterization of the Wadi Al-Majinin watershed (562.37 km²) and its nine sub-basins in northwest Libya using GIS, remote sensing, and WRB soil data. Drainage networks were extracted from a 30m SRTM DEM. Morphometric parameters including drainage density, stream frequency, drainage texture, shape parameters, relief parameters, and hypsometric integral were calculated to evaluate landscape evolution, hydrological behavior, and erosion susceptibility across the watershed. The findings reveal a distinct spatial gradient in landscape maturity and hydrological response from upstream to downstream. The watershed is dominated by infiltration-dominated hydrology across 93% of its area, primarily controlled by carbonate lithology and fractured limestone/dolomite permeability, with Calcisol soils providing complementary infiltration enhancement. This has significant implications for groundwater recharge potential in this arid region, where water resources are critically scarce. Upstream areas exhibit active erosion and serve as primary sediment sources, while midstream zones function as optimal groundwater recharge areas. Downstream outlet sub-basins are heavily influenced by dam-induced flow convergence and require separate hydrological interpretation. The study provides evidence-based guidance for watershed management: Sub-basin 7 is identified as the highest priority for soil conservation; Sub-basin 2 requires flood control measures; and Sub-basin 3 offers the greatest potential for managed aquifer recharge. Historical validation confirms the reliability of GIS-based methodology. This research contributes a replicable methodological framework for watershed characterization in data-sparse arid regions and offers practical tools for sustainable water resource management in Libya.