Groundwater

Groundwater models simulate groundwater flow in sub-surface aquifers in terms of quantity (level) and quality (such as salinity) using the mathematical or numerical approach. When a Groundwater model is embedded in a management framework these are often referred as managment models.

The study presents the spatial analysis of groundwater levels and its quality for the year 1998 for Kakinada town in coastal Andhra Pradesh. The Deltaic Regional Centre of NIH has been monitoring groundwater levels and its quality in and around Kakinada town since 1994. Groundwater samples have been analyzed for physical and chemical parameters. The variation in each parameter is discussed in the report.

A total of 164 samples were collected from 41 observation wells during the months of February, May, August and November 1998. The area covered by these observation wells is around 82 sqkms. The groundwater table contours were plotted for pre-monsoon (May 98) and post monsoon (November 98) periods and the approximate flow direction had been demarcated.

The study attempts to determine the water quality of all available sources of water be it surface, ground or waste water and find out the likely sources of pollution for the Hardwar district of Uttar Pradesh. The physico-chemical parameters of the water were determined. The effect of monsoon on the water quality was studied by collecting and analyzing the pre and post monsoon samples.

The study on groundwater quality of Greater Guwahati analyses various trace elements in samples and ascertains that their concentration is much higher than the tolerance limit prescribed for drinking water. The trace element analysis focuses on metals such as Cu, Co, Cd, Fe, Zn and Pb.

Owing to the inadequacies of piped water supply, the Greater Guwahati area depends on groundwater from ringwells and tubewells for drinking purposes. Groundwater is mostly polluted from the effluents discharged by industries on land, seepage from sewage lines & tanks and application of pesticides on agricultural land. Due to the low flow velocity, groundwater once contaminated will remain so for longer periods. Metals assume significance because of their greater toxicity, accumulative and non-biodegradable behavior. 

The report presents a review of several aspects of non-point source of pollution, like extent and effects of pollution in surface and groundwater bodies, pollution control, monitoring, modeling and management options. Non-point source pollution originates from diffuse land areas that contribute pollutants to surface and groundwater bodies. Sediments, nutrients and pesticides are transported from croplands either in a dissolved form in runoff or through adsorption onto eroded soil particles. Apart from this it can also enter groundwater through leaching.  

The report presents a literature review on the status of research related to saltwater intrusion and groundwater management in coastal and deltaic environments in the east coast of South India. The area is typically characterized by highly productive and alluvial aquifers and high use of both surface as well as groundwater. Seawater intrusion into the freshwater aquifers is extensive due to increased pumpages.

A quantitative understanding of the patterns of movement and mixing between freshwater and saline water and the factors that influence these processes is stressed in the report. It presents the mechanics of saltwater intrusion through studies by Ghyben and Herzberg and later on by Hubbert. A comprehensive review of studies by Reilly and Goodman relating to saltwater intrusion is discussed. Later advances in understanding saltwater-freshwater relationship through numerical models like sharp interface model and miscible flow model are described.

The study analyses the surface and groundwater quality of Ghataprabha representative basin during pre-monsoon and post-monsoon seasons. It looks at the primary impact of land use and cropping pattern on water quality using physico-chemical analysis, geo-chemical classification of groundwater samples and monitoring of groundwater quality.

Streeter-Phelp’s model is applied to understand the variation of dissolved oxygen along the course of the river from a point source. The study attempts to understand the impact of irrigation return-flow and use of pesticides, fertilizers & manures on surface and groundwater quality. The literature review offered indicates a dearth of studies on the subject for hard rock catchments and puts forward the need to do basin-wide as against area-wide studies.

Often groundwater pumping is undertaken assuming the resource to be infinite. This myth has been shattered in the last few decades with increasing scarcity and deterioration in terms of quality as a consequence of over-exploitation and mismanagement of this resource to meet competing demands for drinking water and other needs in urban cities. However, managing groundwater is not an easy task.

Organizer: ACWADAM

Main Topics:

This paper refers to the recent plans by the Government of India to undertake artificial recharge of groundwater in over-exploited areas of the country to meet the demands for water and raises certain fundamental questions about the methods used for analysing the hydrological and economic impacts of the interventions.