Impact of land use and land cover transformations on groundwater level dynamics in the Kamrup district of Assam.

Geoenvironmental sustainability faces critical challenges due to unprecedented land use land cover (LULC) transformations driven by unplanned urban growth and unprecedented population demands. The effects are severe in developing regions with an agrarian economy and inadequate surface water quality. However, the interaction of these LULC changes with freshwater resources remains underexplored and necessitates further investigation. Therefore, in this study, we have applied a methodology to assess the impact of spatiotemporal dynamics of LULC on the groundwater levels of the Kamrup district in Assam between 1990 and 2020. Multi-temporal Landsat satellite imageries were analysed using Random Forest classification in the Google Earth Engine platform to generate the LULC maps for 1990, 2001, 2010 and 2020, while Mann-Kendall (MK) statistics were employed to detect groundwater level trends across 21 monitoring wells for 30 years. The results indicate a substantial urban expansion from 2 to 15%, accompanied by a 25% reduction in forest cover and a 45.5% loss in wetlands during the three decades. The change detection analysis indicates that 11% of wetlands, 24.2% of agriculture and 14.7% of barren land have been converted to urban use in contrast to the transformation of 42% of the barren land and 21% of the forest cover to agricultural land. Additionally, the MK test statistics of the groundwater levels indicate declining trends in 43% of well locations in the pre-monsoon season and 29% of wells in the post-monsoon season. The bivariate statistics between the groundwater levels and the LULC changes demonstrate that 38% of wells with declining trends are located in agriculture lands and 11% in urbanised areas, highlighting the persistent stress on groundwater resources due to overexploitation by anthropogenic activities. These findings underscore the urgent need for sustainable land use planning and groundwater management strategies in rapidly developing regions.