Fluctuations of groundwater table (GWT) has great role in agriculture through assured supply of irrigation in industry and other fronts. As such, probability of possible GWT also plays an important role in terms of efficient usages of this valuable resource. An attempt has been made to find probability distributions taking seasonal (January, May, August and November for 2005 to 2013) information on GWT for the districts under five agro-climatic zones of West Bengal. The study reveals that 17 districts of West Bengal, India, can be categorised into 6 probability model groups: Weibul, Normal, Weibul (3P), Log Logistic (3P), Log Normal (3P) and Gamma (3P). These models can be used to ascertain the probability of occurrences of GWT in specific district. Cluster analysis, using GWT figures for various seasons over the period of study reveals that the districts could be grouped into four clusters, which in-turn may facilitate clusterwise strategy for restricting the depletion of GWT depth or maintenance of the same. These techniques can be used for intradistrict GWT analysis for efficient monitoring of GWT.

Geospatial technology was utilized in this study to specifically delineate groundwater potential zones. IRS-LISS III data in conjunction with Survey of India toposheet (1:50,000) and extensive field data were used for the preparation of various thematic maps. Various thematic maps have been prepared for geology, geomorphology, slope, relative relief, land use, drainage density, lineament density, transmissivity, storativity and water table fluctuation. Thematic maps have been integrated in GIS by assigning suitable rank and weightage to each parameter based on their respective significance. Integrated groundwater potential map is a genuine tool decidedly resourceful for sustainable groundwater development and management. The charisma of this innovative method is that, this model can be used in any other area to functionally demarcate groundwater potential zones, and hence will be of immense societal significance.

The occurrence of high nitrate levels in groundwater has to be recognized as a threat to humans and animals. Infant methaemoglobinaemia and nitrate poisoning in livestock occur at unexpected times and places. Nitrate pollution in the groundwater is one of the major pollution problems. In the last few decades nitrate concentration in groundwater has increased dramatically. Groundwater contamination by nitrate (NO3-) is a global problem and is most often associated with leachates derived from fertilizers and animal or human wastes. The study presented here was carried out in Varanasi district. The nitrate content in water was investigated during premonsoon (March-April, 2013) and postmonsoon (November-December, 2013) seasons and compared with the standard values given by WHO. Eighty four, from different cropping systems (i.e. rice-wheat, rice-vegetable, vegetable-vegetable, pulse-pulse, orchard and sugarcane) groundwater samples were collected from the bore wells. The analysis of nitrate in these water samples reveals that some villages have a high concentration of nitrate, exceeding permissible limits of WHO (45 mg/L), which is due to the more than the required quantity of nitrogen based fertilizers, water, manure and pesticides are used extensively which all contribute to the non point source contamination of nitrates in groundwater of the study area.