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Abstract:
: Generating land capability class guidelines at a watershed scale has become a priority
in sustainable agricultural land use. This study analyzed the area of cultivated land use situated
on the non-arable land-capability class in the Jema watershed in the Upper Blue Nile River Basin.
Soil surveys, meteorological ground observations, a digital elevation model (DEM) at 30 m, Meteosat
at 10 km × 10 km and Landsat at 30 m were used to generate the sample soil texture class, average
annual total rainfall (ATRF in mm), terrain, slope (%), elevation (m a.s.l) and land-use land cover (%).
The land capability class was analyzed by considering raster layers of terrain, the average ATRF and
soil texture. Geo-statistics was employed to fit a surface of soil texture and average ATRF estimates.
An overlay technique was used to compute the proportion of cultivated land placed on non-arable
land. As per the results of the terrain analysis, the elevation (m a.s.l) of the watershed is in the range
of 1895 to 3518 m. The slope was found to be in the range of 0 to 45%. The amount of estimated
rainfall ranged from 1640 to 131 mm with value declined from the lower to the higher elevation.
Clay loam, clay and heavy clay were found to be the major soil texture classes. Four land capability
classes, i.e., II, III, IV (arable) and V (non-arable), were identified with proportions of 28.56%, 45.74%,
22.16% and 3.54%, respectively. Seven land-use land covers were identified, i.e., annual crop land,
grazing land, bush land, bare land, settlement land, forestland and water bodies, with proportions
of 42.1, 35.9, 8.90, 8.3, 2.6, 2.1, and 0.2, respectively. Around 1707.7 ha of land in the watershed is
categorized under non-arable land that cannot be used for annual crop cultivation at any level of
intensity. Around 437 ha (3.5%) of land was cultivated on non-arable land. To conclude, the observed
unsustainable crop land use could maximize soil loss in upstream regions and siltation and flooding
downstream. The annual crop land use that was observed on non-arable land needs to be replaced
with perennial crops, pasture and/or forest land uses.
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