Correlating Spatial-Temporal Changes in Ukai Reservoir with Universal Soil Loss Equation and Geospatial Indices

Abstract

Ukai reservoir experienced flood incidents in 2006, 2013 and 2019, resulting in significant damage to property and infrastructure. The objective is to analyze the spatial-temporal changes in the inundation of reservoirs and soil loss. Normalized difference water index (NDWI), modified normalized difference water index (MNDWI), universal soil loss equation (USLE) and landuse/ land cover (LULC) were applied. Landsat-8 data were collected from 2013 to 2020 for both pre- and post-monsoon periods. A decreasing trend in water inundation areas was observed from 2015 to 2016, possibly due to excess irrigation and power generation. The 2016 experienced an increased water spread area, which could be attributed to heavy precipitation in the upstream catchment. A high rainfall erosivity factor (96.27-1427.58) indicates intense rainfall, which denotes a more remarkable ability of an area to detach and transport soil particles. A high soil erodibility factor (0.05-0.34) depicts higher erodibility. The topographic factor (0 -146.01) indicates that more erosion occurs in steeper areas. The highest predicted annual soil loss was in the moderately high erosion category. Low crop management factor (0-1) denotes loss. Overall, soil loss in this area is increasing, underscoring the need for effective soil conservation measures. The average annual soil loss factor (26.64-44.05) depicts an increase in soil loss. LULC analysis shows that agriculture (69.77% in 2018) and barren land (24.38% in 2020) are the two predominant classes. The variation in the area was influenced by rainfall during the post-monsoon period, excess irrigation and electricity generation during the pre-monsoon period. © 2025 Elsevier B.V., All rights reserved.