A Novel Bare Soil Index for Enhancing the Mapping of Bare Soil Area – An Indicator of Urban Expansion

Bare soil mapping is inevitable for the monitoring of soil resources, as it acts as a major indicator of urban development.Although remote sensing based indices are largely used for the delineation of bare soil, their effectiveness has always been a challenge due to overlapping spectral characteristics of the bare soil and built up areas.Recently, built up indices have been employed to increase the accuracy of bare soil mapping, which can induce discrepancies due to lesser sensitivity in smaller patches of bare soil areas in high density urban regions.In this context, modified normalized difference bare soil index (MNDBSI) is developed using a logical combination of index with additional constraint for the precise delineation of bare soil area using Sentinel 2 images.The qualitative and quantitative analyses adopted to evaluate the performance of the MNDBSI revealed an overall agreement value of above 95% and the improvement percentage of MNDBSI over the other indices compared in terms of spectral discrimination index and transformed divergence varied from 8% to 166% and 15% to 97%, respectively, across all study areas.The comparative analyses of results indicate that MNDBSI is an effective alternative to the existing indices for precise bare soil mapping which can be used as a promising indicator of urban expansion.