SOIL EROSION RISK ANALYSIS IN MUBI SOUTH LOCAL GOVERNMENT AREA, ADAMAWA STATE, NIGERIA
SOIL EROSION RISK ANALYSIS IN MUBI SOUTH LOCAL GOVERNMENT AREA, ADAMAWA STATE, NIGERIA
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Date
2017-05
Authors
RICHARD, Thlakma Sunday
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Abstract
The study analyzed soil erosion risk in Mubi South. The data used are:land use andland cover map derived from Satellite data of 2016. Slope map, derived from ASTER data, rainfall map derived from 2016 rainfall data of Nigeria and masked to the watershed area. RUSLE and RMMFM model parameters were derived from satellite imageries and laboratory analysis for the analysis of soil erosion risk computation in the watershed area. The methods employed include use of RUSLE and RMMF models with the aid of Geospatial techniques using ArcGIS 10.3 Software. The result showed that gully erosion range between 3m to 20m deep, 20–50m wide and mostly more than 100 m long. It was found that sandy soil covered about 65% of the study area, 18% of silt and 17 % clay particles.About 29% of the area was covered by agricultural activities, 19% covered by forest, and 25% not cultivated and covered by bare land. The study area has about 0.58 to -0.07 normalized difference vegetation index (NDVI) with majority of the area within the lower topography of 570m above sea level. The estimated soil loss in the study area was 3.5 t/ha/yr as at the time of this research. The result of the study also showed that average rate of soil detachment is 1 t/ha/yr. The average transport capacity of overland flow is 1.5 t/ha/yr. Average soil per detachability by raindrop is 69.6 t/ha/yr and total soil particle detachment is 69.66 t/ha/yr and average soil erosion of 3.52 t/ha/yr was estimated. The areas of high soil resistivity had soil aggregate stability ranges from 0.29 to 0.41. Predicted soil particle detachability in the watershed are; 24.2 to 37.2 t/ha/yr (low), (37.2 to 49.7) t/ha/yr (medium) and between 49.71 and 69.6 t/ha/yr(high) respectively. Those areas that had low soil particle detachment were attributed to the high soil resistance. Again, Predicted soil Transport Capacity of Overland Flow indicated about 98% of the study area had about 1.57 t/ha/yr soil transport capacity rate of overflow in the watershed. Predicted total soil particle detachment in the study area was high(about 69.66 t/ha/yr of annual total soil particle detachment) and about 25.26 t/ha/yr low values. It was also found that the south east of the study area had about 25.26 t/ha/yr of the (total low soil particle detachment). It was found that about 50% of the watershed has very low soil erosion risk which was mostly covered by vegetation, some part of agricultural area and hilly regions. About 17% of the study area is covered by low soil erosion risk, 12% moderate, 6% moderately high, 11% high and 4% very high. The moderate and low soil erosion risk classes of the watershed were found along the foot of the hills and mountainous area. Very high to high erosion classes were characterised by gully and rill erosion in the study area. It was found that the highest annual soil loss occurred in an urban area. RMMF and RUSLE models showed performance best test for the goodness-of-fit measure. It was recommended that other soil erosion models be applied in the study area for further comparism and analysis of soil erosion
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DOCTORATE DEGREE INGEOGRAPHY DEPARTMENT OF GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT, FACULTY OF PHYSICAL SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
SOIL EROSION,
RISK ANALYSIS,, MUBI SOUTH LOCAL GOVERNMENT AREA,, ADAMAWA STATE,, NIGERIA