Groundwater

The report describes the results of the study of arsenic pollution in groundwater in Nadia as well as the hydro-chemical study of the river Hoogly in West Bengal. The alluvial tract along the river Hoogly covering a stretch of around 470 km encompassing eight districts is affected by arsenic pollution of ground water, the source being geogenic.

The study attempts to estimate the recharge to groundwater due to rainfall and irrigation using tritium tagging techniques in parts of Narsinghpur district under the Narmada catchment in Madhya Pradesh. The estimation of recharge to groundwater is crucial to better water resources management, particularly in arid and semi-arid regions.

The study presents detailed investigations of the chemical quality of groundwater in Jammu and Kathua districts (J & K), carried out to evaluate the suitability of water for various uses. The quality of groundwater of the area has been studied based on the physico-chemical analysis of thirty seven water samples collected from open wells between June and December, 1996.

Various parameters like pH, conductance, alkalinity, hardness, chloride, sulphate, sodium, potassium, calcium and magnesium have been determined for all the samples and compared with the standards to evaluate its suitability for drinking and irrigation purposes.

Irrigation water quality has been computed on the basis of Doneen’s Permeability Index and residual Sodium Carbonate. The higher values of some parameters at certain locations indicate the contamination in groundwater and make the water unsuitable for specific applications.

In this study, unsteady flow towards a fully penetrating well screened in both the aquifers of a two-aquifer system separated by an aquitard has been analyzed using numerical approach. Existence of multi-aquifer systems is common in a sedimentary basin.

The study attempts to develop a mathematical model for transport of a solute in groundwater by taking the mass balance of the dissolved pollutant over a static elementary volume in three cartesian coordinates.

The management of groundwater resources is becoming a complicated task due to the overwhelming pressure on groundwater and the changing scenario of groundwater quality (physical, chemical and biological). 

The hydraulics of groundwater is governed by many bounded and un-bounded factors. The mixing of constituents in groundwater is an important factor that shapes the occurrence of constituents in any precise location at any given time.

In the study, a drain spacing formula has been derived rigorously considering the variation in radial flux and the area above drain level in the radial flow zone. Hooghoudt’s drain spacing formula is based on an implied assumption that in the radial flow zone there is no spatial variation in the flux and hence no vertical recharge in this zone. The Hooghoudt’s formula computes maximum water table height very close to that computed by the rigorous method.

The report presents a detailed review of mathematical modeling of flows in alluvial streams. Various computer codes for this are presented and a model for simple-island case is prepared. Branched flows in open channels with alluvial conditions occur in natural and man-made systems. Analysis of such flows by mathematical modeling is important considering its applications in water resources and environmental engineering.

The report deals with the procedures to estimate dispersion coefficient from exit concentration observed due to a step change in the concentration input. A simple method as well as an optimization method has been evolved and the application of the methods on published datasets discussed.

Dispersion occurs in many problems of groundwater flow, such as pollution from concentrated and distributed source, sea water intrusion, seepage of polluted surface water through rivers or lakes and changes in water quality due to artificial recharge. Application of the solution of advection-dispersion equation in soil media for prediction and forecasting of solute concentrations requires the estimate of coefficient of hydrodynamic dispersion, commonly known as ‘dispersion coefficient’.

In the study saltwater intrusion processes in a hypothetical homogenous and multi-layered coastal aquifer system are simulated using the United States Geological Survey (USGS) finite element model for saturated-unsaturated fluid density-dependent groundwater flow with energy transport of chemically reactive single species solute transport (SUTRA) for different boundary conditions and aquifer parameters.

The saltwater intrusion profiles for steady-state or transient conditions are obtained and analyzed. The effects of changes in the permeabilities of aquifers and aquitards, changes in the influx at the boundary, and changes in dispersivities in medium on the saltwater intrusion process are investigated.

The report summarizes aspects of the theory of anisotropic flow in porous media and reviews the methodology for computing hydraulic potentials in an unconfined aquifer system. An algorithm has been devised by applying appropriate transformation techniques for anisotropic domain.

Numerical experiments have been performed using the algorithm to compute hydraulic potentials in certain hypothetical anisotropic aquifer systems. A number of cases have been studied with different coefficients of anisotropy for the aquifer as well as the angle inclination of the bedding planes of the soil strata. The simulated hydraulic potentials in the anisotropic domain are established as equipotential lines in vertical sections.