The morphometric investigation of the Gelda watershed in the Lake Tana sub basin: implications for managing soil and water resources

Morphometric analysis, or the quantitative measurement and mathematical analysis of landforms, is the foundation of conservation initiatives at the watershed level. It aids in estimating the predominance of infiltration and runoff, as well as other related hydrological features of a watershed, such as erosion and sediment transport, which have a substantial influence on resource conservation. The aim of this study was to evaluate the morphometric characteristics of the Gelda watershed in the Lake Tana Subbasin in order to properly apply soil and water conservation strategies. For this study, SRTM DEM with 30 m resolution was used to estimate the morphometric parameters. The watershed has a basin length of 333.68 Km and a total area of 280.90 km2. Gelda Watershed is a fifth-order drainage basin. Of these drainage networks, 138 are first-order, 33 are second-order, 9 are third-order, 2 are fourth-order, and 1 is a fifth-order stream. As the stream order rises from one to five, the number of streams for each respective order decreases. The basin is comparatively mountainous and prone to flooding, as indicated by the high mean bifurcation ratio of 3.59. It indicates high structural disturbance, the availability of erodible soils, and the occurrence of high overland flow and discharge. The drainage density of the Gelda watershed is 1.19 km/km 2 . It depicts the watershed’s steep impervious area and the high level of flooding with sparse vegetation cover. The smaller stream frequency indicates that the basin experienced low relief, permeable bedrock, and the presence of alluvial fans and flood plains. It had a roughness number of 0.85, indicating high relief and increased drainage density. The elongation ratio revealed that the basin is both elongated and low-class. Furthermore, hypsometric integration revealed that the watershed is nearing maturity and has experienced considerable erosion and dissection. Researchers and managers of watersheds can better understand the characteristics of the watershed by using the drainage morphometry information provided by the study’s results. The results show the necessity for soil and water conservation strategies and natural resource management.