Abstract
This study aims to identify the vulnerable landscape areas using landslide frequency ratio and land-use change associated soil erosion hazard by employing geo-informatics techniques and the revised universal soil loss equation (RUSLE) model. Required datasets were collected from multiple sources, such as multi-temporal Landsat images, soil data, rainfall data, land-use land-cover (LULC) maps, topographic maps, and details of the past landslide incidents. Landsat satellite images from 2000, 2010, and 2019 were used to assess the land-use change. Geospatial input data on rainfall, soil type, terrain characteristics, and land cover were employed for soil erosion hazard classification and mapping. Landscape vulnerability was examined on the basis of land-use change, erosion hazard class, and landslide frequency ratio. Then the erodible hazard areas were identified and prioritized at the scale of river distribution zones. The image analysis of Sabaragamuwa Province in Sri Lanka from 2000 to 2019 indicates a significant increase in cropping areas (17.96%) and urban areas (3.07%), whereas less dense forest and dense forest coverage are significantly reduced (14.18% and 6.46%, respectively). The average annual soil erosion rate increased from 14.56 to 15.53 t/ha/year from year 2000 to 2019. The highest landslide frequency ratios are found in the less dense forest area and cropping area, and were identified as more prone to future landslides. The river distribution zones Athtanagalu Oya (A-2), Kalani River-south (A-3), and Kalani River- north (A-9), were identified as immediate priority areas for soil conservation.
Highlights
Land-use change is one of the threats to soil erosion, and it worsens the global environmental problem
land-use land-cover (LULC) change, soil erosion hazard, and their associated dynamics of Sabaragamuwa Province were evaluated using the revised universal soil loss equation (RUSLE) model combined with a geographic information systems (GIS) environment
Future research could be focused on investigating the pattern of average soil erosion rate and total estimated soil erosion against Landslide frequency ratio (LFR) at river distribution zone (RDZ) level, using a statistical method to predict the effect of soil erosion rates on the occurrence of landslide incidents at RDZ level
Summary
Land-use change is one of the threats to soil erosion, and it worsens the global environmental problem. Soil erosion is one of the main reasons of land degradation [1,2]. Soil erosion is a natural phenomenon that is defined as detachment of the soil particles and transport due to the action of an erosive agent such as wind, water, gravity, or anthropogenic perturbations [3,4,5]. Soil erosion by water is known as water erosion. Erosion is a vital indicator to identify the soil erosion hazard [8]. The kinetic energy of water drops detaches the soil particles and water flows on the surface by creating narrow cannels. Erosion can be described as accumulated surface runoff in narrow cannels and removal of the soil from considerable depths [9]
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