Hydrological Spatial Analysis of Wadi Alkuf Catchment Area, Cyrenaica, Northeastern Libya

Abstract

Morphometric analysis reveals that the Wadi Alkuf drainage, on the northern flank of Al Jabal Al Akhdar, Cyrenaica, northeastern Libya, is characterized by dendritic to sub-dendritic drainage pattern. The development of stream segments in the basin area is apparently affected by intermittent rainfall and geological structure control such as joints set, fractures and faults, as the general area is of limestone karstic character. The analysis reveals that the total number and total length of stream segments reach maximum of 6233 segments in first order streams but decrease to 620 segments in 6th order streams. The bifurcation ratio (Rb) between different successive orders varies between 0.7 in 6th order and 3.5 for third order passing through 2.43 in second order. A mean bifurcation ratio of 1.42 indicates a partial structural control. The stream frequency (Fs) value of 8.87 exhibits positive correlation with the drainage density value of 1.97, whereas the drainage density (Dd) indicates clearly that the region has permeable subsoil and relatively moderate vegetation cover. Calculated Circularity Ratio (Rc) of 0.215 and Elongation Ratio (Re) of 0.15 suggest that the drainage basin is typically elongated in shape, has a low discharge of runoff and relatively permeable subsoil condition. Form Factor (Rf) of 0.22, represents a flatter peak of flow for a longer duration. Flood flows of such elongated basins are easier to manage than of circular basins. It becomes evident that morphometric analysis would contribute to understanding of the dominant geo-hydrological characteristics and processing of watershed planning and management utilizing geospatial techniques based on GIS application and Digital Terrain Model (DTM) analysis.