Assessment of Runoff and Soil Loss under Natural Vegetation Cover and Rainfall in a Semi-Arid Catchment, West Pokot County, Kenya.
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Date
2022
Authors
Bukoma, Emmanuel
Obando, Joy
Murimi, Shadrack
Journal Title
Journal ISSN
Volume Title
Publisher
East African Nature and Science Organization
Abstract
Soil erosion has become a major cause of land degradation with regrettable
economic losses. It has affected livelihoods of many agro-pastoral communities in
Arid and Semi-arid Lands (ASALs). There is need for continuous assessment of
soil erosion in these areas in order to provide sufficient data on soil loss for soil
resource management, conservation, and land use planning. The purpose of this
study was to determine the rate of soil loss by water for soil conservation planning
in West Pokot County, Kenya. Two adjacent fields with variable vegetation cover
density were identified in a semi-arid catchment for runoff plot research.
Vegetation cover on the fields was measured using the transect line-intercept
survey method. Field 1 had 25–50% vegetation cover while field 2 had 50–75%
vegetation cover. On each field, three identical erosion plots with dimensions 20 m
along the slope and 10 m wide were constructed. Runoff and sediment from the
plots were measured for fifteen rainfall-runoff events during the long rains season.
Data was analysed using correlation analysis and linear regression methods. The
results show that runoff production varied from 1.03% to 1.44% of total rain water.
Soil loss from the plots was 120.3–155.5 g/𝑚2
. Runoff-rainfall correlation analysis
showed a significant positive relationship (r =0.9609, P<0.05%) with 92.33%
variance in runoff production. Soil loss had significant positive relationship with
runoff (r =0.9840, P<0.05%) with 96.83% variance in soil loss. The study found
that runoff production and soil loss was slow in the field with dense vegetation
cover. Studies project an increase in human and livestock populations in semi-arid
areas. This points at possible decrease in vegetation cover and increase in the rate
of soil loss by water. The study recommends development of a soil conservation
and management strategy in the study area.
Description
Article
Keywords
Soil Erosion, Semi-arid lands, Runoff plot, Sediment, Slope grade
Citation
Bukoma, E., Obando, J., & Murimi, S. (2022). Assessment of Runoff and Soil Loss Under Natural Vegetation Cover and Rainfall in a Semi-Arid Catchment, West Pokot County, Kenya. East African Journal of Environment and Natural Resources, 5(1), 134-147.