CS(AR)-10/99-2000 : Evaluation of groundwater table and quality in Krishna delta, A.P.

Abstract

The shallow groundwater levels and quality data pertaining to Krishna Delta for about 20 years have been analyzed. The trend analysis of groundwater level data of shallow wells indicated that in the upper part of Krishna Delta the groundwater table raised from the year 1979 to 1999. It may be due to the dense canal network in the delta and increase in irrigated area over a period of time_ The ground water flow direction is observed as the replica of 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 ground water storage.

The spatial distribution maps of EC, SAR and C1/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 are prepared. The spatial distribution maps of C1/HCO3 ratio in shallow wells (open wells), filter points and tube wells indicated that there is significant vertical variation of salinity in the study area. The saline water intrusion is not observed in shallow aquifer, but it is observed in deeper aquifer (tube wells) in the study area. Detailed studies are necessary to confirm salt-water intrusion in deeper aquifers of Krishna Delta.