A Study to ascertain the Optimum Yield from Groundwater Source in the Eastern Part of Kolkata Municipal Corporation Area in West Bengal, India

Abstract

The increasing stress on fresh water resources due to ever-rising demands and profligateuses as well as growing population and industrial establishment of Kolkata is an issue ofgreat concern. The purpose of this study is to make a quantitative estimate of the availablegroundwater resources in the eastern part of Kolkata for efficient utilization andmanagement of groundwater resources. The methodology involved the investigation,drilling, lowering, collection and analysis of main well and observation wells data andgroundwater quality as well. Based upon the study of lithological logs as also the electricallog, the sub-surface deposition of the assembly pipes have been determined. The resultsindicate that the aquifers are composite and composed of sands and overlying silts/claybeds. Long term Tests pumping indicate that the main well may be capable of a long termdischarge rate of 120 m3/hr restricted at 120 m and 156.65 m. The aquifer parametersfrom the study area are estimated from the analysis of short and long durations pumpingtest data. For the alluvial aquifer, transmissivity of 1491 m2/d, hydraulic conductivity of49.7 m/d and storage coefficient of 0.0064 are recommended found by using differentmethods. Long duration pumping tests have indicated that the maximum drawdown inwater table by 4.89 m may be achievable by radius of influence about 682 m. After theclosure of pumping operation, recuperation test was also carried out in the main wells aswell as also from observation wells. Recovery test was monitored for 20 hrs after closureof pumping. Slope of the residual drawdown from t/t’ indicated aquifer transmissivity of1322 m2/d and therefore hydraulic conductivity of the alluvial sand aquifer is 44 m/dhaving an aquifer thickness of 30 m. The physico-chemical and bacteriological analysis ofgroundwater of two pumping wells were tested and the results showed the groundwatermust be disinfected before supplying to the consumers.