Spatio-Temporal Variation of Groundwater Table with Relation to Rainfall Distribution: A Study in Nadia District, West Bengal

Abstract

Groundwater is the main source of freshwater, and its limited quantity makes it precious, which seeks sustainable management. Fluctuation in the groundwater table due to overconsumption is very dangerous in a highly arsenic-prone region like Nadia district as it can increase the contamination at a significant level. The present study assesses the relationship between the long-term rainfall (1998–2018) and the corresponding water table variation over the Nadia district. The spatio-temporal variation of the depth of the groundwater table has been analysed, and the trend of rainfall and depth of the groundwater table during the study period (1998–2018) has been carried out with the non-parametric Mann–Kendall trend test (1975). The study revealed that the area experienced a major shift in rainfall distribution in 2010, 2012 and 2018. The Mann–Kendall trend test indicates a negative trend in the time series of both the rainfall distribution and depth of the groundwater table. The significant fluctuation in the depth of the groundwater table is found in the last decade. The correlation between rainfall distribution and depth of the groundwater table shows a negative relationship, which signifies that more rainfall means a decrease (rising) in the depth of the groundwater table. The negative correlation between annual rainfall and fluctuation of the groundwater table and RMSE also suggested that a year with excessive rainfall has a low fluctuation of the groundwater table, while a year with rainfall deficiency has a high degree of fluctuation of the groundwater table.