Hydrological study of the Wadi Jarf basin using Geographic Information Systems

Abstract

This scientific paper investigates the hydrological and morphometric characteristics of the Wadi Jarf basin, located in the Sirte region of central Libya, utilizing Geographic Information Systems (GIS) and Digital Elevation Model (DEM) data with a resolution of 12 meters. The research aims to establish a precise database for the basin's spatial, formal, and topographical features to understand their direct influence on hydrological behavior, including runoff volume and peak discharge. The methodology integrates regional, analytical, and quantitative approaches, applying various mathematical equations to derive critical parameters. Results indicate that the basin covers a substantial area of 2519.81 km² with a perimeter of 341.69 km and a length of 103 km. Morphometric analysis reveals that the basin's shape tends toward an elongated or triangular form rather than circular, with a circularity ratio of 0.271 and an elongation ratio of 0.55. These geometric properties, combined with a low average slope of 2.9 meters per kilometer, significantly impact the flow timing. Hydrologically, the study found that the concentration time reaches 21 hours and the lag time is 12.6 hours, reflecting the slow response of the basin to rainfall events due to its large area and low relief. The estimated annual runoff volume is approximately 0.021 billion cubic meters, representing only 4.38% of the total rainfall, while the flow velocity was recorded at 4.9 m³/hour. The drainage network consists of six orders with a total of 3429 stream segments, showing a low drainage density of 1.36 km/km². The hypsometric integral of 29.18 suggests the basin has reached an advanced geomorphological stage (old age). The study concludes that the risk of flash floods is relatively low and recommends leveraging these GIS-based results for sustainable water resource management and agricultural planning in the region.