Potential impact of rainfall variability on groundwater resources: a case study in Uttar Pradesh, India

Groundwater systems are largely influenced by rainfall variability which is considered the principal source of recharge. The present study explores the relation between the long-term rainfall (1992-2014) and the corresponding water table variation over the Varanasi district. The temporal trends of both the water table and long-term rainfall were analyzed using non-parametric Mann-Kendall time-series trend test. The district experienced an annual rainfall average of 876 mm during the study period. In the recent decade (2003-2014), the amount of annual rainfall and rainy days declined by 42 mm and 8 days, respectively, were compared with previous decade (1992-2002). The water table fluctuation had also shown decreasing trend in the recent decade and were compared with the previous decade. The frequent fluctuations in rainfall anomaly and water table fluctuation had been related to El Nino and La Nina events to study the impact of these events at regional scale. The intense cultivation of water intensive crops as well as rainfall variation was found to be one of the major causes behind the water table fluctuation in the study area. Therefore, artificial water recharge and change in cropping pattern through cultivating less water consuming crops with efficient irrigation technologies of water management may help to overcome the upcoming adverse situations.