National Institute of Hydrology

This report presents the various methodologies for correct assessment of irrigation return flow, which is one of the most significant components  in the water balance of irrigation command areas. A part of the water applied to the irrigation fields percolates deep to recharge the groundwater and is known as  irrigation return flow. In this report methodologies have been presented for assessment of irrigation return flow through soil moisture modeling, water balance approach, experimental determination and groundwater modeling. 

The study attempts to explain flood wave propagation in natural and artificial channels within the perspective of site-specific rating curve. The study looks at the impacts of channel characteristics – bed slope, flood plains, channel shape, expansion-contraction combination, inactive storage, Manning’s roughness, expansion and contraction on flood wave propagation.

The study looks at the various processes and mechanisms of wind erosion as well as the factors that contribute to the increase or decrease of wind erosion in desert areas in the particular context of the Great Indian Desert. The method of estimation of soil loss in a desert area due to wind as suggested by Woodruff and Siddoway on the lines of Universal Soil Loss Equation (USLE) is explained.

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 study presents automated mapping of snow cover using a new spectral channel of Indian Remote Sensing (IRS-IC) data for the Spiti sub-basin of the Satluj river basin. Snow is an important phase of the hydrological cycle and the estimation of snowmelt runoff in the Himalayan rivers, either seasonal or daily, is of immense use in proper management and use of water resources in the basins.

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 study applies a hydraulic simulation model, Hydrologic Engineering Centre (HEC-1) to Baitarni river for modeling hourly flows of the river at Anandapur gauging site. HEC-1 model had been developed by US Army Corps of Engineers, for rainfall-runoff modeling. It provides a powerful automatic optimization technique for estimation of some of the parameters. The optimization technique of the model has been utilized in the present study and model parameters have been calibrated and validated for the study area.