Quantitative soil erosion risk assessment due to rapid urbanization in the Cox’s Bazar district and Rohingya refugee camps in Bangladesh (original) (raw)
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Research Square (Research Square), 2023
Soil erosion is the major cause for loss of soil fertility in many parts of the world. The conversion of forested areas into settlements and tea plantations has made Pettimudi hills in Iddukki district of Kerala prone to soil erosion. To compute the extent of soil erosion in the selected study area, the Revised Universal Soil Loss Equation (RUSLE) method is adopted. The present study analyses the soil erosion for the years (2017 to 2021) by varying the Land Use Land Cover (LULC) classes with constant R-factor (rainfall and runoff factor) and LS-factor (length-slope factor). The LULC for Pettimudi hills are classi ed into three categories, namely settlement, dense vegetation, and water bodies. An extreme rainfall event that took place on 6 th of August 2020 resulted in drastic extensive soil erosion in the study area. The Supervised Classi cation method along with Maximum Likelihood Estimation techniques are used for LULC classi cation. The C-factor (Cover and management factor) ranges from 0 to 0.1 for the years 2017 to 2021 and is based upon the LULC classes identi ed in the study area. The conversion of vast areas of forest land into settlements and tea plantations decreases the soil organic matter and hydraulic conductivity of the soil which in turn increases the K-factor (soil erodibility factor), as found in the study area. The gathered results shows that the maximum erosion is seen in southern and northwestern parts of the study area. The extent of soil erosion is seen to have increased from 0.25 tonnes/ha to 2.06 tonnes/ha in the time period of 2017 to 2021. It is observed that the 56 % of increase in the soil erosion during the study period is mainly due to LULC changes as well as with the extreme rainfall conditions in the area.
AIMS Geosciences, 2020
Soil erosion is one of the major environmental problems in northeast India, and identifying areas prone to severe erosion loss is therefore very crucial for sustainable management of different land uses. Tuirial river basin, where shifting cultivation is a major land use, is prone to severe soil erosion and land degradation, linked to its fragile geo-morpho-pedological characteristics. Though several models are available to estimate soil erosion the Revised Universal Soil Loss Equation (RUSLE) is more appropriate and practical model that can be applied at a local or regional level. The objective of the study was to estimate annual soil loss in the upper Tuirial river basin by using RUSLE where various parameters such as rainfall erosivity factor (R), soil erodibility factor (K), slope length (L), slope steepness factor (S), crop management factor (C) and practice management factor (P) were taken into consideration. Land use land cover (LULC) derived from Satellite data of Sentinel 2A Digital Elevation Model (DEM) were integrated into the model. Our results revealed that the river basin has an average annual soil loss of 115.4 Mg ha −1 yr −1 , and annual sediments loss to the tune of 6.161 million Mg yr −1 from the basin. About one-fourth (24.78%) of the total basin could be classed as very high to very severe soil erosion prone area that need immediate conservation measures. Besides, the erosional activities were perceived directly proportional with the slope values in the basin. However, regardless of the rugged mountainous terrain of the basin, the unscientific practice of shifting cultivation, associated with high intensity of rainfall is the principal cause of soil erosion. The results of the study is expected to contribute to adaptation of appropriate soil and water conservation measures in the basin 526 AIMS Geosciences Volume 6, Issue 4, 525-544. area, and similar studies may also be extended to other unexplored areas for proper watershed management in state of Mizoram.
Soil Erosion Analysis Using GIS and RS in Makawanpur District, Nepal
Journal of Forest and Natural Resource Management
Although soil erosion is a common phenomenon and a serious hazard in many areas of the Makawanpur district, it is still challenging to estimate and assess the amount of soil erosion. This study investigates the distribution of soil erosion in the Makawanpur district using the Revised Universal Soil Loss Equation (RUSLE) and Geographic Information System (GIS). RUSLE model parameters were collected from various sources. Topography, rainfall, soil characteristics, and soil conservation techniques were considered in the study, among many other erosion factors. These variables were multiplied to determine the average soil loss. Based on the severity of the erosion, the final results of soil erosion rates were divided into six classes. Very serious class accounts for 11.31% of the land (>80 t h-1 yr-1), followed by severe which is 9.76% of the land with erosion rate rates ranging from (40-80 t h-1 yr-1), very high is 17.41% of the land with rates ranging from (20-40 t h-1 yr-1), follo...
Environmental Earth Sciences, 2018
Estimation of spatial extent of soil erosion, one of the most serious forms of land degradation, is critical because soil erosion has serious implications on soil fertility, water ecosystem, crop productivity and landscape beauty. The primary objective of the current study was to assess and map the soil erosion intensity and sedimentation yield of Potohar region of Pakistan. Potohar is the rainfed region with truncated and complex topography lying at the top of the Indus Basin, the world's largest irrigation networks of canals and barrages. Spatially explicit Revised Universal Soil Loss Equation (RUSLE) Model integrated with Remote Sensing-GIS techniques was used for detecting/mapping of erosion prone areas and quantification of soil losses. The results show that the Potohar region is highly susceptible to soil erosion with an average annual soil loss of 19 tons ha −1 year −1 of which the maximum erosion (70-208 tons ha −1 year −1) was near the river channels and hilly areas. The sediment yield due to the erosion is as high as 148 tons ha −1 year −1 with an average of 4.3 tons ha −1 year −1. It was found that 2.06% of the total area falls under severe soil erosion, 13.34% under high erosion, 15.35% under moderate soil erosion while 69.25% of the area lies in the low (tolerable) soil erosion. Chakwal and Jhelum districts of the region are seriously affected by erosion owing to their topography and soil properties. The information generated in this study is a step forward towards proper planning and implementation of strategies to control the erosion and for protection of natural resources. It is, hence, necessary that suitable water harvesting structures be made to control water to prevent soil erosion and provision of water in the lean season in this region. Tree plantation and other erosion control practices such as strip cropping can also minimize soil erosion in this region.
ISPRS International Journal of Geo-Information
Land degradation caused by soil erosion is considered among the most severe problems of the 21stcentury. It poses serious threats to soil fertility, food availability, human health, and the world ecosystem. The purpose of the study is to make a quantitative mapping of soil loss in the Chitral district, Pakistan. For the estimation of soil loss in the study area, the Revised Universal Soil Loss Equation (RUSLE) model was used in combination with Remote Sensing (RS) and Geographic Information System (GIS). Topographical features of the study area show that the area is more vulnerable to soil loss, having the highest average annual soil loss of 78 ton/ha/year. Maps generated in the study show that the area has the highest sediment yield of 258 tons/ha/year and higher average annual soil loss of 450 tons/ha/year. The very high severity class represents 8%, 16% under high, 21% under moderate, 12% under low, and 13% under very low soil loss in the Chitral district. The above study is help...
2024
Geo-environmentally, the eastern Himalaya region is highly vulnerable to erosion and soil loss geomorphic hazard due to humid tropical to humid sub-temperate climate (receives 1600-3200mm mean rainfall), young and highly erodible rock formations (mainly comprised of sandstones, siltstones and shales), fragmented reshaping geomorphology, high erodibility of surface and sub-surface soils. Despite that, anthropogenic activities have been enhancing this geo-environmental vulnerability to erosion hazard through rapid unplanned urbanization with associated infrastructural development in urban to suburban areas and shifting cultivation practices in rural areas. Addressing this burning environmental problem, a geospatial technology-based case study of the Kohima district, Nagaland state (India) from eastern Himalaya is presented here. Various experiential models are available for computing soil erosion; however, a Revised Universal Soil Loss Equation (RUSLE) integrated with the GIS framework was applied in the current study due to its robustness and high accuracy level. Five key RUSLE factors such as erosivity of rainfall (RE), erodibility of soil (ES), erodibility of rock (ER), slope length (LS), crop management (CM) and conservation practice (CP) were calculated using required data sets in a GIS environment. RE ranges between 648.12-1294.15 MJ mm/ha/h/year, ES varies minimum of 0.10 to a maximum of 0.41 among the existing 15 classes of soils, ER factor values ranges 0.01-0.04, LS factor values range between 0 and 1.22, CM factor values vary from a minimum of 0.0 for dense forest area to maximum 1.80 for buildup areas whereas the CP value varies 0.1-1.0 across the study region to land use/cover pattern. The accumulated impact of these erosion and soil loss factors resulted in a quite higher average rate (about 16 t/ha/year) than the threshold value of soil erosion (< 10 t/ha/year). This value ranges from 1-92.18 t/ha/year and poses. Thus, it has been essential to minimize the high rate of erosion through intensifying CP factors at the government level, community level and even individual level by adopting scienti c crop patterns, agro forestry and reforestation programs. If these necessary actions were not taken timely, it may lead to other erosion-induced geomorphic hazards such as land degradation, mass movement, landslides, slope failure etc.
2020
Geo-information science has attempted to estimate the actual soil loss and its correlative interpretation with land use and cover types in an agricultural land, Sambhunath Municipality. Among several empirical and physically based soil erosion models, Revised Universal Soil Loss Equation (RUSLE) are widely used and employed to estimate soil loss based on rainfall, topographic contour, and soil map. The soil erosion ranges values are found from 0 to 2635 t ha-1 yr-1 in terms of soil loss per year in the municipality. Soil erosion rates are found highly correlated with the increasing exposure of land surface in Chure range mostly on forest area. Agriculture lands spatially concentrated in 51.70% of the Municipality extent, is contributing significantly as of 16293 t ha-1 yr-1 of the total potential soil loss from fertile cropland. Based on severity of soil loss, cultivation agriculture areas are priority for reducing soil loss for optimum agriculture management practices in land use p...
Journal of Degraded and Mining Lands Management, 2024
Soil erosion remains a persistent menace to the sustainability of agriculture and the environment in tropical mountainous regions. Soil erosion assessment is therefore necessary to identify degraded land areas for implementing effective conservation and management strategies. Hence, this study focuses on estimating potential soil erosion and analyzing their spatial patterns in the Chite watershed, situated in the Eastern Himalayas, India, using the Revised Universal Soil Loss Equation (RUSLE) model in Geographic Information System (GIS) platform. Various datasets encompassing remote sensing, ground observations, and laboratory analysis were employed to prepare the model’s input factors. The estimated mean erosion rate of the study area is 6.10 t ha-1 year-1, which produces a total soil loss of about 357580.90 t year-1. Spatial analysis reveals that about 5.79% of the watershed is under a relatively severe erosion category, contributing 70.13% of the total soil loss. Soil erosion appraisal with respect to the land use/ land cover (LULC) indicates a considerable consequence of various anthropogenic activities in the watershed. Higher rates of soil erosion are mainly observed on the bare land, cropland, and settlement areas which are characterized by steep and continuous slopes. The present findings were also validated with previous work undertaken in some comparable regions. This research can serve as a reliable tool towards the development of successful soil conservation measures and for promoting sustainable land use planning in this ecologically sensitive tropical mountainous region.
Land Degradation & Development, 2011
Management practices to minimise soil erosion can be effectively carried out if the magnitude and the spatial distribution of soil erosion risk areas are known. Prioritisation of soil erosion risk areas is a challenging task, especially in the developing countries because of non-availability of relevant data and analytical tools for such an assessment. As a result, it becomes difficult to establish appropriate soil conservation measures on the risk-prone areas to reduce soil loss and ensure development of a sustainable management of soil resources. Such a database can be better generated and analysed in a geographical information system (GIS) environment to delineate and prioritise the soil erosion risk areas at state or regional level. Therefore, a methodology was developed to assess the soil erosion risks in eastern Himalayan region by integrating spatial data on prevailing erosion rates and soil loss tolerance limits in GIS environment. By comparing the potential erosion rates with permissible rates, we observed that about 58Á94 per cent of total geographical area (TGA) of the region requires different degrees of erosion management and 28Á38 per cent of TGA falls under no treatment category because of higher values of permissible erosion limits. It can be successfully applied to assess and prioritise soil erosion risks in any region or country and identify best management practices to bring the erosion losses within the permissible limits.