DEM-BASED GIS ANALYSIS OF HYDROLOGICAL BEHAVIOUR IN THE ENUGU BASIN, SOUTH-EASTERN NIGERIA

Abstract

This study applied Digital Elevation Model (DEM) based Geographic Information System (GIS) hydrological modelling to analyse terrain-controlled hydrological behaviour within the Enugu Basin, southeastern Nigeria. Unlike earlier studies that relied largely on descriptive geomorphology, this research employs reproducible GIS procedures to quantify drainage organisation, flow convergence and terrain influence on runoff processes. A 30-m resolution Shuttle Radar Topography Mission (SRTM) DEM was processed in ArcGIS 10.8 using sink filling, Deterministic Eight-node (D8) flow-direction, flow-accumulation and watershed delineation algorithms. The results reveal structurally controlled drainage patterns, distinct runoff convergence zones and a strong topographic control on hydrological response across the basin. Flow-accumulation outputs highlight potential runoff concentration corridors rather than direct erosion magnitudes, consistent with established hydrological theory. These patterns indicate areas of heightened hydrological vulnerability linked primarily to terrain configuration and drainage connectivity, corroborating previous studies in southeastern Nigeria. The findings demonstrate that DEM-derived hydrological layers provide an objective basis for identifying erosion-prone zones, guiding flood-risk screening and informing land-use suitability assessments in data-scarce environments. The study further underscores the need to integrate DEM-based hydrological modelling into environmental planning, erosion-control strategies and watershed-scale management frameworks within the Enugu Basin. It also highlights the importance of field validation, institutional capacity building and the future adoption of higher-resolution elevation data to improve micro-scale runoff characterisation. Overall, the research confirms the analytical value of DEM-based GIS hydrological modelling as a cost-effective and scientifically robust approach for sustainable land-use planning and environmental management in developing regions.