Evaluation of the impact of Long-term Land Use Land Cover Change on Groundwater Recharge in the Periyar River Watershed, India

Abstract:

Land use Land Cover (LULC) changes have a significant impact on the regional groundwater flow system, especially for regions that are undergoing rapid urbanisation and inadequate fresh surface water. There is limited quantitative evidence on how changes to LULC in the tropical area affect the groundwater recharge. The present study focuses on the evolution of the long-term impact of LULC change on Groundwater recharge in the Periyar river watershed in Ernakulum district, Kerala, India. Due to rapid anthropogenic activities in the study area, the groundwater flow system is severely affected by influencing the water scarcity. The impacts of land-use changes on the groundwater system in the Periyar River Basin for the recent four decades were analysed in the perspective of groundwater recharge using the Soil and Water Assessment Tool (SWAT) using a detailed LULC record from 1992 to 2019. The response of groundwater recharge rates to LULC was analysed by incorporating land-use changes in the SWAT model. The comparative analysis between simulated recharge corresponding to initial and subsequent LULC depicts an overall decline in the groundwater recharge from 1992 to 2019. Statistical analysis from the study indicates a maximum of 45% decrease in groundwater recharge observed in 12 sub-basins and a minimum of 10% reduction in another ten sub-basins among 52 sub-basins. The expansion of the built-up land with a decrease in agricultural land and barren land is considered as the primary contributor to the reduction in groundwater recharge. The study depicts the significant variability in long-term groundwater recharge resulting from temporal changes in LULC. The study, therefore, points out the needed regulations in anthropogenic activities to address the criticality in land resource management.