National Institute of Hydrology

The study assesses waterlogging in a canal command area in Rohtak and Jhajjhar districts through waterlogging area zonation using multi-spectral and multi-temporal imagery like IRS LISS III data of pre and post monsoon period. Seasonal and permanent waterlogged area and standing water were delineated on the basis of remote sensing data, digital elevation model and groundwater data.

The study develops regional flood frequency relationship and flood formulae based on recently developed efficient techniques of flood frequency analysis to estimate floods of desired return periods for small to moderate size gauged and ungauged catchments of the middle Ganga plains (sub-zone 1F) encompassing parts of Uttar Pradesh, Bihar and West Bengal. A regional flood formula has been developed by coupling the L-moment based regional flood frequency relationship with the regional relationship between mean annual peak flood and the catchment area.

The study assesses the suitability of groundwater for drinking and irrigation use and examines the likely impact of Yamuna river water quality on groundwater. Delhi is faced with severe problems associated with groundwater quality and quantity. The quality varies spatially and seasonally, with depth and is primarily governed by the extent and composition of dissolved solids present in it. Surface water bodies play a role and the hydraulic gradient determines the lateral and vertical migration in the groundwater flow system.

Groundwater samples were collected through extensive field surveys covering entire Delhi area representing various geo-hydrological and land-use conditions. The data has been analysed with respect to BIS and WHO standards to examine its suitability for various uses. The area has a peculiar feature of infiltration of surface water to groundwater from river Yamuna and from various drains.

The study estimates the snow cover area for four major basins in the Himalayan region viz. Chenab up to Akhnoor, Ganga up to Devprayag, Satluj up to Bhakra and Beas up to Pandoh using IRS - IC and ID WiFS data. Snow cover estimation was done for the years 1997-2000 using image processing system ERDAS Imagine. The maximum and minimum snow cover extent for the month of September-October and March-April were delineated and on the basis of these the depletion curves for each basin was made for the four years. This output is useful for carrying out snowmelt runoff modeling.

The hydrological study for the experimental representative basins, Ghataprabha and Malaprabha, of the Krishna river basin attempts to standardize and develop methodologies for providing solutions for understanding and solving various hydrological problems of the hard rock regions of India.

Representative basins are basins, which are selected as representative of a hydrological region within which hydrological similarity is presumed and can be used for intensive investigation of specific problems of the hydrological cycle. This can then take a wide-ranging role representing a broad area to which the data can be transferred. 

The research attempts to demonstrate the potential of remote sensing in base mapping and change detection in urban land-use in Delhi, with the aim of understanding the urban hydrology. The study uses IRS LISS III sensor and ERDAS Imagine image processing system to establish the potential of remote sensing techniques in obtaining synoptic and repetitive coverage of the city to monitor the patterns of urban growth and urban fringe activity.

The study estimates the initial abstraction coefficient for six watersheds in various agro-climatic zones of Karnataka from rainfall-runoff events by asymptomatic fitting of Curve Numbers calculated from observed rainfall-runoff data using Soil Conservation Service (SCS) model of United States Department of Agriculture (USDA). The SCS method assumes the initial rainfall abstraction as the fraction of potential maximum retention of soil.

The study aims to determine the climatological water balance of Krishnai river basin in Goalpura, Assam using the popular Thornthwaite’s concept of Potential Evapotranspiration (PET) to calculate the availability of water for various uses. The method offers a firm basis for appraising the problems related to water development projects in the planning stage and provides a sound footing for operating and managing the system. 

The study applies advanced models of design storm like Flood Analysis and Protection Systems (FLAPS) and HEC-1 for rainfall-runoff simulation employing selected short-term events of three basins of the north-eastern region – Myntdu-Leska (Meghalaya), Krishnai and Dudhnai (Assam). The results are used to study the sensitivity of the model parameters with respect to different hydrological parameters of the basin. The performance of these methods is evaluated by analyzing the isolated events. An attempt has been made to evaluate the non-linearity in rainfall-runoff response, using a simple storage-runoff dynamic model. The relationship of incipient soil moisture and transmissivity with direct runoff and recharge is studied.

The study estimates geomorphological parameters and soil loss using the Universal Soil Loss Equation (USLE) and Geographical Information Systems (GIS) techniques for the Juni nadi watershed in Jammu Siwaliks with the idea of helping planners develop soil conservation strategies. Geomorphological characteristics of a river basin shape runoff processes and the occurrence of floods especially in the mountainous areas. In ungauged catchments with limited data, such as Juni nadi watershed, these parameters can be useful in understanding the hydrological characteristics. Reliable estimates of soil loss too can be useful in formulating watershed strategies to reduce soil loss to acceptable levels.