India

The report develops rainfall-runoff modeling for simulating and forecasting the flow from a catchment, and in determining the inflow series for the ungauged catchments on the basis of records of gauged catchments.

Because of the scarcity of data, mostly lumped models have been used to model the rainfall-runoff process in a catchment. However distributed models are more accurate and need to be adopted for modeling the complex processes at the scale of basins.

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.

The report presents a methodology to assess the probability distribution of Dissolved Oxygen (DO) based on the Streeter-Phelp’s equation. The methodology involves the use of first order analysis and Monte Carlo simulation to analyze the uncertainty associated with DO. The mean and standard deviation of the parameters have been assumed as same for the study’s probability distributions.

The study develops the wavelet element method for hydrological application purposes in general and modeling of flow in a canal due to breach of bank in particular. Due to high seasonal variability of rainfall and cyclones in coastal India, flood discharges cause frequent breaching of canals.

Canal breach modeling is of great significance in open channel hydraulics. The study of breach of a canal is a relatively new one as compared to dam breach, which is a well researched field. The analysis of the problem is complicated due to dynamics of flow within the canal. The limitations of the above model due to the one-dimensional model analysis of the problem is hoped to be overcome in two or three dimensional analysis.

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 describes the software, which has been developed for flood control regulation of a system of reservoirs. The reservoirs can be gated or ungated, and the system can have any combination including weirs and diversions. For operation of reservoirs, the scenario has been divided into two categories depending on the reservoir level and inflows - normal operation and emergency operation.

The input data requirements of the software are modest. This software along with previously developed software for conservation operation would provide a complete set of tools to analyze any system configuration for the range of purposes for which reservoirs are commonly built in India.

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.