Assessing spatio-temporal variations in groundwater table depth and salinity using geostatistics and its relation with groundwater balance in a salt affected soil

Abstract

In order to study spatio-temporal variation in groundwater table depth and salinity in shallow groundwater table area, a field study was carried out at Nain experimental farm of ICAR-Central Soil Salinity Research Institute (ICAR-CSSRI) situated in Nain village of Panipat, Haryana. Total 27 observation wells had been installed in such a way that few among them were near to working tubewell for observing groundwater fluctuation due to pumping. 8 observation wells were near to pond and remaining observation wells were distributed in the area confined between the pond and surface drains to observe effect of natural recharge taking place from water bodies on groundwater table fluctuation. Besides continuous groundwater table monitoring, periodic assessment of groundwater salinity (EC ) was also done. Spatio-temporal w behavior of groundwater table and groundwater salinity was studied using Ordinary Kriging (OK) procedure in Arc GIS 9.3 software. The variograms and krigged spatial maps were generated for pre and post monsoon seasons of 2013 and 2015. Different inflow and outflow components of groundwater were characterized using groundwater balance method. Spatial variability maps of groundwater table in pre monsoon season indicate an increase in 36% area of shallow groundwater table (<2 m below ground level-bgl) during 2013 to 2015. Whereas, area under -1 low saline groundwater (0-4 dS m ) was increased and reduction in higher -1 saline groundwater (8-16 dS m ) area was recorded during 2013 to 2015. Analysis of groundwater balance of the experimental farm revealed that this reduction in groundwater salinity and rise in groundwater level might be attributed to intrusion of fresh water from outside cultivated land and seepage from nearby water harvesting structures and drain. Based on the results, it can be concluded that geo statistical analysis provides an understanding of groundwater flow behavior and dynamics of groundwater salinity, which can be used to prioritize the area for implementing the groundwater management plan in salt affected areas.