Assessing Soil Degradation: A Comprehensive Study Using Soil Degradation Index (SDI) in Godrahav Watershed

Abstract

Soil degradation is an important problem for watersheds that contain agricultural and natural areas within their border. This study was conducted to assess soil degradation using soil degradation index (SDI). The watershed was divided into transects at 500m intervals in the north-south and the east-west directions. Except for the hard-to-reach points because of topography, disturbed and undisturbed soil samples were taken from 138 sample points at the intersections of the transects. The SDI was calculated using the measured soil parameters including particle size distribution, aggregate stability, aggregation rate, mean weight diameter, dispersion rate, bulk density, porosity, field capacity, wilting point, organic matter content, pH and electrical conductivity. The spatial distribution patterns of these parameters were defined using geostatistical analyses. Slope, elevation, aspect and land use type of the watershed were also mapped using the Geographic Information System (GIS) technique. The results of the study showed that soil degradation can be quantified using an index value, and that basic soil properties can serve as parameters for this index. These parameters affect index values with different weighting, and these weighting values can be calculated by correlation analysis. Moreover, according to the distribution maps, SDI showed spatial variability due to the land use, altitude, and aspect, but it did not vary regularly due to the slope. Based on the findings, it is recommended to implement land use-specific soil management strategies across the watershed. Regular SDI-based monitoring and geospatial analysis can support early detection of degradation and guide sustainable land use planning.