EFFECT OF LAND USE AND LAND COVER CHANGES ON SOIL EROSION USING REVISED UNIVERSAL SOIL LOSS MODEL

Abstract

The burgeoning urban landscape of Dhaka, Bangladesh, grapples with the escalating challenge of soil erosion, contributing to land degradation within the city. This study employs the RUSLE model integrated with Remote Sensing and GIS techniques to scrutinize the intricate dynamics of soil erosion within the urban fabric of Dhaka. The distinctive geography of Dhaka, along with its quick development and fluctuating climate, highlights the city's susceptibility to soil erosion. The study finds that the average rate of soil erosion within the study area is around 26.59 tons/ha/year. These findings indicate that there are geographical variations associated with particular land use patterns. The dynamics of soil erosion are largely dependent on the parameters of the RUSLE model. The R factor, which indicates the erosivity of rainfall, varies from 974.53 in 1990 to 867.17 in 2020. The slope characteristics-indicating LS factor falls between 0 and 2.25, while the K factor is recorded at 0.0189. Significant fluctuations in the cover management factor (C), which shows a value of 0.93 in 1990, 1.03 in 2000, 0.98 in 2010, and 0.934 in 2020, as well as the support practice factor (P), which spans from 0.2 to 0.934, are discernible and provide concrete proof of changing land use and conservation strategies. Changes in the climate throughout time may have an impact on the variations in the R factor. The basic characteristics of the soil that affect its erodibility have stayed mostly constant. This stability may be explained by a consistent soil composition, restricted land use changes that don't significantly alter the properties of the soil, efficient conservation techniques that reduce the risk of increased erodibility, the inherent resistance of some soils to change, or regional variations in how land use changes affect erodibility. Slope features can change as a result of infrastructure initiatives, urban development, or construction operations altering the natural topography. Changes in vegetation and land cover are suggested by variations in the C factor. Deforestation, urbanization, and afforestation activities can all have a big impact on soil management and cover. Changes in the P factor may be related to how well and how widely conservation measures are used in the research region. Lower P values may result from increased use of terracing, contour farming, or other erosion control techniques. A dynamic pattern within the research area is revealed by looking at the historical evolution of soil erosion rates. The rate of soil erosion peaked in 1990 at 31.39 tons/ha, indicating a high degree of susceptibility. The rates decreased in the following years, reaching 26.78 tons/ha in 2000 and 24.65 tons/ha in 2010. The rate significantly decreased over the ensuing ten years, reaching 23.54 tons/ha in 2020. These results suggest that land usage, conservation methods, or other environmental conditions may change in the future. Improved land management techniques, greater public knowledge of soil conservation, or changes in land use that lessen erosion susceptibility could all be contributing factors to the observed drop in soil erosion rates over time. The research is useful in a number of important areas. By exploring the intricacies of urban soil erosion in Dhaka, it offers a thorough grasp of the variables affecting this occurrence, such as crop management, conservation techniques, slope characteristics, rainfall erosivity, and soil erodibility. Policymakers and urban planners working on sustainable development and environmental preservation in Dhaka will find this information to be quite helpful. The results might also have an impact on the region's soil fertility. By eliminating the top layer of fertility, soil erosion can affect soil fertility. Therefore, it is important to understand the dynamics of soil erosion. The results of this study could be useful in developing ways to reduce soil erosion, maintain soil fertility, and increase agricultural output in Bangladesh, a country whose economy is mostly dependent on agriculture. This study makes contributions to environmental preservation, urban planning, and maybe agricultural sustainability within the particular setting of Dhaka, Bangladesh.