A geospatial approach for understanding the spatio-temporal variability and projection of future trend in groundwater availability in the Tawi basin, Jammu, India

The overexploitation of groundwater in the foothills of the Himalayas at Jammu has led in a steady decline of groundwater levels in the recent years. The causes of the groundwater scarcity, however, is unknown due to a lack of long-term trend analysis of groundwater monitoring and scientific investigations. Therefore, the objective of this research is to investigate the groundwater variability in the alluvial aquifers of Tawi River basin of the Jammu district by applying a non-parametric approach using Mann-Kendall and Sen's slope approach. In addition, a stochastic seasonal Autoregressive Integrated Moving Average (ARIMA) model was also used for forecasting time series groundwater level. The results revealed that during the pre-monsoon (PRM) season, 66.6% of the monitoring wells suffered groundwater decreases, compared to 53% during the post-monsoon (POM) season across the whole study area. The steepest slope was found in the Kandi belt with maximum water table declined to 26 m below ground level (bgl) in 2018 compared to 8.44 m bgl in 2009 with an average rate of decline of 1.109 m/yr in PRM season. Siwalik region reported a decline of groundwater level at the rate of 0.173 m/yr and 0.27 m/yr in PRM and POM respectively. However, water table in Sirowal region improved marginally in PRM and POM season with a mean raise of 0.05 m/yr and 0.08 m/yr respectively. According to the time series forecasting by stochastic simulation, if the current situation continues, the groundwater level in the Kandi region would decline by 9.46 m and 9.38 m respectively, over the observed values in 2018 to reach a level of 27.82 and 24.38 m bgl in PRM and POM respectively by 2025. The spatio-temporal analysis showed that the groundwater extraction in the aquifers of Kandi region was higher than that of the Siwalik and Sirowal region. The spatiotemporal trend and projection of groundwater levels is quite helpful in identifying the most vulnerable places, as well as addressing the current and future condition of groundwater levels for optimal resource planning and management of groundwater resources in the sustainable ways.