Browsing by Author "Sang C."

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    Influence of Land Use Land Cover Changes on Soil Erosion in Elgeyo Escarpment, Kenya
    (East African Agricultural and Forestry Journal, 2022) Kanda R.; Sang C.; Letema S.
    Land use land cover changes (LULC) are known to cause land degradation in various forms including soil erosion. The Elgeyo Escarpment is within the Kenya’s Rift Valley, a mountainous section with rugged terrain and receives fairly high rainfall. These factors, coupled with unsustainable LULC changes, make the escarpment prone to soil erosion challenges. Despite this vulnerability, information on soil loss is scanty. This paper evaluates the impact of LULC changes on soil erosion occurrence in the Elgeyo Escarpment between 1995 and 2020. Revised Universal Soil Loss Equation model, remote sensing and ground truths were used. The results revealed that the average intolerable soil erosion rates were 14.0 t/ha/yr and 18.76 t/ha/yr in 1995 and 2020, respectively. Scrubland, cropland, grassland, forest and built-up areas contributed 67.1%, 20.1%, 7.8%, 4.8% and 0.2%, respectively of the total soil loss in 1995. By 2020, the contributions of shrubland and forest to erosion had dramatically declined to 39.8% and increased to 39.4%, respectively. Cropland, shrub/grassland and built up areas contributed 20.2%, 0.3% and 0.3%, respectively. The highest rates of soil erosion occurred in built-up areas converted from shrub/ grassland (1.04 t/ha) followed by cropland converted from forest (0.59 t/ha). Soil erosion rate increased with increased slope angle owing to high velocity and runoff erosivity, with areas having slope >300 experiencing the highest rate (1225 t/ha/y). Therefore, there is need to review land use and soil conservation practices to ensure sustainable management of the escarpment.
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    Spatio-Temporal Dynamics of Land Use and Land Cover in Elgeyo Escarpment, Kenya
    (East African Agricultural and Forestry Journal, 2022) Kanda R.; Sang C.; Letema S.
    The Elgeyo Escarpment has undergone land use and land cover (LULC) changes over the last five decades. However, past LULC change assessments focused on forests and river basins and little on LULC changes and their drivers in the escarpment. This paper, therefore assesses spatio-temporal dynamics of LULC and their drivers. Satellite images were analyzed to assess LULC changes using remote sensing and geographical information system (GIS) techniques; and validated using ground-truthing. Structured questionnaires were administered to 180 household heads, eight focus group discussions and key informant interviews conducted to determine LULC change drivers. The survey participants were over fifty-five years of age, to provide historical LULC change trends. The images were pre-processed and classified using the maximum likelihood algorithm in Environment for visualizing images (ENVI), with images overall classification accuracies being over 70%. The results indicate LULC conversions varied in trends and magnitude. Between 1995 and 2014, grassland and shrubland decreased by 78.15% and 24.41%, respectively. Conversely forest, built-up and cropland gained by 411.82%, 200.95% and 13.62%, respectively. In 2014- 2020, forest cover increased by 63% while grassland, built-up, shrubland and cropland decreased by 79.69%, 39.14%, 21.57% and 11.80%, respectively. Overall, forest, built-up and cropland gained while shrubland and grassland decreased. Notably, forest gained by 734.52% while shrubland decreased by 40.72%. Population growth is the primary LULC driver triggering increased demand for food (88.9%), settlements (52.2%) besides cattle rustling (44.4%) and forest evictions. Periodic LULC assessments are crucial to guide policies and guidelines formulation for the sustainable management of the escarpment.