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- Title
Terrain mapping and analysis for land management: the case of Megech-Dirma watershed, sub-basin of the Blue Nile basin, Northwest Ethiopia.
- Authors
Habtu, Worku; Katihally, Jayappa
- Abstract
Digital mapping of terrain using existing topographic data is possible, and depending on the study size, it can improve existing land surface information. For the Megech-Dirma watershed, both the primary and secondary terrain attributes were mapped and analyzed. In this study, the topography of the Megech-Dirma watershed mapping and analysis has been done. The data inputs were a digital elevation model and satellite images of 30-m resolution. The soil data was based on the soil map of the world published by the Food and Agriculture Organization of the United Nations. The method we used to calculate the various topographic features was based on geometry and elevation calculations from digital elevation models and satellite images. ArcGIS 10.4 software was used to map and analyze the Megech-Dirma watershed terrain. The prominent landforms of the Megech-Dirma watershed are low mountains (31.53%), irregular plains (28.18%), smooth plains, flat landforms (19.16%), and breaks (14.86%). The slope classes are 0–10 degrees (gentle slope) (62.65%), 15–25 degrees (moderate slope) (25.19%), and > 45 degrees (steep slope) (4.14%). The north, northwest, and northeast are the steepest terrains, with a slope greater than 45 degrees, reaching 75 degrees and showing very steep terrain. The geological elements include basalt, marsh soils, alluvium, and colluvium. The terrain wetness index of 5.71 occurs in locations with more extensive upslope areas drained to the gentler slope of the watershed near Lake Tana. The topographic ruggedness index results indicate that the southern portion of the watershed is nearly level. In contrast, the northern and northeastern parts are rugged terrains, which could be susceptible to soil erosion. Based on stream power index analysis, the upper part of the Megech-Dirma watershed, especially the north and northwest parts, is the source of many streams flowing to the south, where erosion could occur. Around 9.72 km2 area is under the shallow soil depth of 0–25 cm, whereas about 608.32 km2 area is between 25 and 100 cm and 564.99 km2 area of land is from 100 to 150 cm depth, which is necessary to maintain soil fertility and boost agricultural productivity. Eutric Leptosols (46.45%), Eutric Vertisols (44.03%), and Chromic Luvisols (7.75%) were major soil types. Clay soils cover 57.83% and clay to clay loam 41.43%, which are the significant textures. Regarding land use, cultivated land, followed by grass and shrublands, is dominant, whereas urban, wetland, water bodies, and plantations cover a minor area. Finally, steeply sloped areas with high mountains and fault areas were cultivated for many years. Because of the continuous cultivation of the watershed's land without rest, it was degraded. This needs carefully planned land use and management to avert land degradation.
- Subjects
BLUE Nile River Watershed (Ethiopia &; Sudan); TERRAIN mapping; LAND management; DIGITAL elevation models; LAND degradation
- Publication
Arabian Journal of Geosciences, 2023, Vol 16, Issue 1, p1
- ISSN
1866-7511
- Publication type
Article
- DOI
10.1007/s12517-022-11110-5