Impact of Land Use/Cover Changes on Soil Erosion in Western Kenya

Benjamin Kipkemboi Kogo,Lalit Kumar,Richard Koech

doi:10.3390/su12229740

Abstract

This study examined the impact of land use/cover changes on soil erosion in western Kenya in the years 1995 and 2017. The study used the GIS-based Revised Universal Soil Loss Equation (RUSLE) modelling approach and remote sensing assessment. The results showed that the average soil loss through sheet, rill and inter-rill soil erosion processes was 0.3 t/ha/y and 0.5 t/ha/y, in the years 1995 and 2017, respectively. Of the total soil loss, farms contributed more than 50%, both in 1995 and 2017 followed by grass/shrub (7.9% in 1995 and 11.9% in 2017), forest (16% in 1995 and 11.4% in 2017), and the least in built-up areas. The highest soil erosion rates were observed in farms cleared from forests (0.84 tons/ha) followed by those converted from grass/shrub areas (0.52 tons/ha). The rate of soil erosion was observed to increase with slope due to high velocity and erosivity of the runoff. Areas with high erodibility in the region are found primarily in slopes of more than 30 degrees, especially in Mt. Elgon, Chereng’anyi hills and Elgeyo escarpments. This study forms the first multi-temporal assessment to explore the extent of soil erosion and seeks to provide a useful knowledge base to support decision-makers in developing strategies to mitigate soil erosion for sustainable crop production.

Highlights

Land degradation is a global environmental threat to ecosystem functions and agricultural productivity [1]
In terms of soil loss severity classes, the results show that 90% of the study areas experienced soil erosion rates of low severity
This study investigated the extent of soil erosion in western Kenya by use of GIS-based Revised Universal Soil Loss Equation (RUSLE) modelling approach

Summary

Introduction

Land degradation is a global environmental threat to ecosystem functions and agricultural productivity [1]. The major form of land degradation is soil erosion, which is caused by the impact of rain drops and runoff leading to soil detachment, transportation and deposition of soil [2]. Soil erosion triggers a series of impacts such as reduced productivity of agricultural lands through the loss of nutrient-rich top soil, depletion of soil organic matter content, degradation of soil structure and water retention capacity [3,4,5,6]. The causes of land degradation in the tropics are a complex nexus of intense climatic conditions, steep slopes, poor agricultural practices, high erosion-risk soils, overpopulation, lack of appropriate policies and overreliance on subsistence crop farming [12]. The dominant processes of land degradation that manifest in Kenya are the loss of soil fertility in agricultural lands through wind and water erosion, deforestation and desertification. Degradation of farms affects the majority of the rural people, who primarily depend on land for rural livelihoods, food, water and economic development [15]

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Conclusion