The report attempts to analyze the shallow groundwater table and water quality data for about 20 years pertaining to the Krishna delta. The trend analysis of groundwater level data of shallow wells indicates that in the upper part of the delta, the groundwater table moved up during the period 1979 to 1999. This may be due to the dense canal network in the delta and increase in irrigated area over a period of time.
The groundwater flow direction is observed to follow the surface gradient except in few places in the eastern delta. The comparison between average rainfall and average groundwater table in the study area indicates that the rainfall recharge may not be the major contribution to the groundwater storage.
The spatial distribution maps of Electrical Conductivity (EC), SAR (Sodium Absorption Ratio) and Cl/ HCO3 indicated that the salinity in the study area increased from the year 1991 to 1999. It is also observed that there is significant change in water quality from pre-monsoon (May) to post-monsoon (November) period. The multiple linear regression models have been developed for EC in shallow aquifer.
The finger print diagram of water quality parameters of filter points, tube wells, canal water, river water and seawater in the study area have been prepared under the study. The spatial distribution maps of Cl/ HCO3 ratio in shallow wells (open wells), filter points and tubewells indicated that there is significant vertical variation of salinity in the study area. Saline water intrusion is observed in deeper aquifer (tubewells) of Krishna delta and detailed studies are necessary to confirm it.
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