Hydrologic and Hydrogeologic Analyses in a Coastal Groundwater Basin, Orissa, India
2003
Rejani, R. | Jha, M.K. | Panda, S.N. | Mull, R.
The Balasore coastal groundwater basin in Orissa, India is under a serious threat to groundwater quantity and quality. Overdraft has resulted in declining groundwater levels and seawater intrusion. The present article focuses on the pertinent hydrologic and hydrogeologic analyses of the basin. Streamflow analysis of two rivers indicated that streamflow reaches its peak in July-August and reduces to a minimum in April-May. The runoff from the basin is estimated at 16.0 x 10 6 , 160.7 x 10 6 , and 525.8 x 10 6 m 3 for dry, normal, and wet years, respectively. The safe yield of the Balasore basin has been determined to be 155.3 x 10 6 m 3 . For normal year and dry years, the gross annual irrigation requirements for the existing cropping pattern are 32 and 178% greater than the safe yield of the aquifer, respectively, while the current groundwater withdrawal for irrigation is 71% more than the safe yield. The regression analysis of monthly rainfall, river stage, and the corresponding groundwater level for the period 1997-1999 revealed that though river seepage and rainfall are two major sources of recharge to the basin, the first source is more significant. The stratigraphic analysis indicated that the basin mainly comprises three confined aquifers. The overall flow of groundwater in the first aquifer is from north to south into the Bay of Bengal. The second aquifer is severely contaminated by seawater intrusion within a 4- to5- km wide tract along the coastline, leaving groundwater unfit for drinking and irrigation purposes. It is concluded that some urgent measures must be taken to ensure sustainable groundwater resources in the basin.
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