Dam Break Flood Studies

The dam break studies at the Institute are aimed at studying various dam break situations and predetermining the peak flood stages and warning time for their possible use in planning safety measures.
The following important studies have been conducted :

	Dam  break analysis of Machhu dam-II failure
	Dam break study of Pulinchintala dam
	Application of dam break programme using data of Gandhi Sagar
	Dam break study of Mitti dam

Hydrological studies of hypothetical dam failure scenarios for some of the major dams of the country have also been completed.

Reservoir Operation
The Institute has developed techniques for reservoir operation. A number of studies are carried out using latest techniques. Real time operation is especially suitable for flood moderation. These studies aim at :

	Conservation torage regulation of reservoir
	Regulation of spillway gates
	Reservoir operation policy
	Flood control regulation l development of flood forecasting system

Snow and Glacier Studies
The snow and glacial hydrology is an important study area of the Institute. The major river basins of Himalayas have significant contribution from snow and ice melt. The studies pertaining to snow and ice melt processes and their modelling are being conducted. Some important studies conducted are :

	Snow and glacier contribution in the Chenab river
	Snow and glacier contribution in the Ganga
	Melt rate studies on Himalayan glaciers
	Melt water storage of a typical glacier

Software Development
During the last three years, the Institute has actively pursued the development of user friendly and interactive hydrological software. The important software developed so far are :

	Unit hydrograph techniques for flood estimation
	Flood estimation for large catchments
	Reservoir analysis
	Estimation of seepage from canal
	Frequency analysis
	Expert system for computing vadose zone parameters

Instrument Development
Reliable and short interval hydrological data are required for many hydrological studies. This calls for development and automation of laboratory and field equipment and their standardization. The Institute has developed a weighing type raingauge and weighing type snow gauge, which can be operated unattended for long duration in remote and inhospitable terrain. The important instruments developed are :

	Microprocessor based rainfall sensor using tipping bucket
	Microprocessor based weighing type rainfall sensor
	Suspended sediment sensor
	Data logger for hydrological measurement
	Automatic snow gauge
	Data logger for soil moisture measurement
	Depth water sampler
	Optical recorder type water lavel sensor
	Microprocesser based automatic infiltrometer

Hydrologic Design  :
The studies carried out at the Institute mainly focussed on design flood estimation using flood frequency analysis and unit hydrograph based approaches, synthetic data generation, water availability studies, network design and development/application of watershed models for different river basins/regions of the country. Besides conventional techniques used for design flood estimation like unit hydrograph approaches and flood frequency analysis, the distributed event based models for different terrain situations have also been studied and developed to estimate design flood.

The Institute has also taken up hydrological studies for the evaluation of dependable flows for the identification of potential sites for small hydro power schemes in the Himalayan region. Regional flood frequency analysis has been carried out at the Institute for Himalayan region and Mahi, Sabarmati and Godavari basins. Relationship between frequency of rainfall and frequency of flood has been studied for a basin of Narmada. Forecasting of monsoon runoff for Vaigai basin in southern Tamilnadu has been carried out by the Institute.

Water Quality
The Institute at its Headquarters, Roorkee and its Regional Centres has been monitoring the surface water quality and ground water contamination at different locations. Models have been applied to assess the problem of water quality for different pollution loads under different scenarios in different seasons. The institute is also working in the area of low cost treatment.

Remote Sensing and GIS Applications
Basic requirement to begin any hydrologic study/analysis is the availability of information and exhaustive data base. Remote sensing technique if used alongwith other available information, may prove useful in supplementing the desired information. The Institute is fully equipped with visual and digital image processing & Geographical Information System (GIS) facilities to carry out various hydrological applications of remotely sensed data. Using the remote sensing technique, the Institute has prepared hydrological land use maps and rainfall-runoff models for Narmada, Ghataprabha and Malaprabha river basins. Remote sensing studies have also been carried out for waterlogging and salinity of IGNP-I and Tawa command area; sedimentation in Tungabhadra reservoir and geomorphology of Sabarmati river basin. In addition to above, the Institute has prepared surface water inventory of Narmada basin and it is proposed to cover some of the major river basins of the country. Institute has also taken up assessment of waterlogging in various affected command areas of the country.

Some of the studies for which these techniques have been applied include :

• snow cover mapping
• land use and soil classification
• erosion studies
• flood plain mapping
• sedimentation of reservoirs and reservoir capacity computations
• assessment of waterlogged areas
• mapping of ground water availability zones

Lake Studies
Various studies pertaining to water balance of lakes, classification of lakes, thermal regime of lakes, sedimentation in lakes and evaporation from lakes are taken up. A comprehensive hydrological study of Lake Nanital has been completed wherein both conventional and isotopic techniques have been used. Besides, some aspects of hydrologic studies on Mansar and Surinsar Lakes (J&K) and Loktak Lake (Manipur) have been undertaken. Comprehensive inventories of lakes in Rajasthan and Madhya Pradesh have been prepared.

Drought Studies
The occurrence of drought in India is not a recent phenomenon. In view of severity of drought problems and lack of understanding of the hydrological aspects associated with the droughts, the Institute has launched studies to better understand the drought impacts from hydrological point of view. Six states of Andhra Pradesh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra and Rajasthan were selected for the study and analysis of hydrological drought. A study for Kalahandi district in Orissa has also been completed.

Groundwater Assessment
Correct estimation of groundwater potential of a region/basin is one of the essential pre-requisite in formulating the efficient management of the available water of the region/basin. Streamflow-aquifer interaction, management of coastal aquifers and groundwater resource evaluation in hard rock regions are some of the important areas in which the Institute has carried out studies.

Studies in connection with modernisation of Upper-Ganga canal system have also been carried out by the Institute.

Dug wells are used extensively in hard rock areas for groundwater. Development of groundwater in these areas requires the knowledge of the dynamics of flow abstractions towards a dug well. The flow towards a well in hard rock areas is governed by the fractures in the rock, the primary and the secondary porosities. The Institute has carried out some investigations to study the flow behaviour in hard rock regions.

A project sponsored by Command Area Development, Indira Gandhi Nahar Pariyojna, Rajasthan to suggest appropriate design of subsurface drainage system in a part of IGNP canal command area has been completed successfully with the objective to design subsurface drainage to reclaim the waterlogged land in Indira Gandhi Nahar.

Design of radial collector well to be installed in the bed of river Yamuna has also been made which will greatly assist in providing good quality water to Agra city.

Assessment of Irrigation Return Flow
Irrigation return flow is one of the most significant components in the water balance of irrigation command areas. A part of the water applied to irrigated field percolates deep to recharge the groundwater which is known as irrigation return flow. In the absence of any studies, it is usually considered as 35% of the water applied for irrigation in case of canal irrigation, and 30% in case of irrigation from groundwater. However, the irrigation return flow depends on many factors including soil moisture characteristics, meteorological parameters, crop type, method of irrigation, depth of water table etc.

The Institute has developed a distributed modelling approach for proper estimation of irrigation return flow.