Field-based geomorphic mapping reveals the rapid expansion of a newly formed gully in Satkura Village in Jalpaiguri District, India
摘要
Gully erosion is one of the most severe forms of water-induced land degradation, rapidly removing fertile soil, reducing agricultural productivity, and leading to long-term changes in landscape morphology. Micro-scale, time-series documentation of such change remains limited in the Himalayan foothills of North Bengal. This study maps and interprets gully evolution in Satkura Village, Jalpaiguri, India, using multi-temporal Google Earth Pro imagery (2012, 2017, 2022, 2024 and 2025), GIS-based manual digitization, GPS verification and rope-tape cross-section surveys. Gully area increased from 1247.54 m² in 2012 to 5687.53 m² in 2025, a net increase of 355.90% and an average absolute expansion of 341.54 m² yr−1. The fastest stage of growth occurred from 2022 to 2024, during which the gully grew by 2071.32 m² (33.51% yr−1; 1035.66 m²). Eleven cross-section profiles indicate substantial variability in width (5.70–25.40 m; mean = 12.44 m, standard deviation = 6.18 m) but comparatively low variability in maximum depth (2.50–3.20 m; mean = 2.92 m, standard deviation = 0.22 m). Width-to-depth ratios (2.03–7.94) indicate a transition from incision-dominated upper reaches to widening-dominated middle and lower reaches characterized by sidewall retreat and irregular benches. The land-use analysis indicates that gully expansion was associated with a 22.70% decrease in agricultural land and an 824.63% increase in fallow land from 2012 to 2025. These results indicate a negative effect of micro-scale erosion on land productivity at very small scales. This study emphasizes the importance of using historical images combined with field data to monitor micro-scale erosion when no previous survey data are available.