Groundwater

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.

The study presents a status report on hydrological problems of hard rock areas related to hydrological network design, groundwater quality, failure of open and borewells, regional flood formulae, groundwater balance studies, reservoir sedimentation, hydrological aspects of droughts, forest hydrology and drainage problems of black soil of the hard rock terrain.

The report tries to review the hydrological studies done in the northeastern region of India by all agencies, governmental or non-governmental. Sufficient care has been taken to include all the salient features of the studies to make it comprehensive. The various information  included in this report are the purpose and year of study, location and extent of the study area with its brief description, data used, list of specific studies along with its results and recommendations wherever possible.

An attempt has been made to pull together all the studies related to hydrology and its allied field. Besides these planned studies done by various departments, research studies done by academic institutions and research and development organizations has also been included.

Organizer: National Institute of Hydrology

Topics:

• Need for Hydrological Investigations
• Conventional Techniques and methods for Hydrological Investigations;
• Application of Remote Sensing and GIS
• Application of isotopic techniques in surface water and groundwater investigations;
• Advance techniques for measurement of soil erosion and reservoir sedimentation
• Advance instrumentation for hydrological investigations; and
• Advance computing techniques for hydrological data analysis.

The study evaluates groundwater on the basis of widely used graphical methods like Piper, Stiff and US Salinity Laboratory classification. The study concludes that, in general, the groundwater in the area varies from medium salinity to very high salinity, the latter being more common in the irrigated stretches. The irrigators are advised to ensure good land and water management practices in the fields, with particular emphasis on creating favorable leaching and drainage conditions to avoid further development of saline conditions in the area. 

The study applies geostatistical techniques to the groundwater quality data of December 1994 in parts of Jammu district. Groundwater quality deterioration has led to considerable interest in the design of investigative studies and monitoring programs on the issue.

Various management measures need to take into account the spatial and temporal behavior of groundwater. The spatial dependence between observations can be expressed by semi variance, which is a measure of the average similarity between observations at a given distance apart. One of the prime reasons for obtaining a semivariogram is to use it for estimation of the variable at unsampled locations.

The study applies a simple five-parameter model based on the concept of probability distributed method as proposed by Moore (1985) to simulate the daily runoff over a nine-year period of 1989-1997 at Tamavaram in Prakasham district of Andhra Pradesh on the Gundlakamma river.