National Institute of Hydrology (NIH)

The report details out the status of landfill and waste disposal technologies in India & abroad and reviews the scientific studies undertaken to support its design for long-lasting performance. Hydrological considerations play a major role in the selection of landfill sites and in the design and performance of landfills for hazardous waste management. A landfill is a form of a biochemical reactor where the municipal solid waste (MSW) comes into contact with moisture, a catalyst, and gets decomposed into solid waste, gases and liquid contaminants (leachate) resulting in the release of heat. The design of the control and recovery systems requires the estimation of amount and composition of gas and leachate accurately, as also the changes in these with time. Lysimeters are used to simulate the landfill performance.

The report presents a review of several aspects of non-point source of pollution, like extent and effects of pollution in surface and groundwater bodies, pollution control, monitoring, modeling and management options. Non-point source pollution originates from diffuse land areas that contribute pollutants to surface and groundwater bodies. Sediments, nutrients and pesticides are transported from croplands either in a dissolved form in runoff or through adsorption onto eroded soil particles. Apart from this it can also enter groundwater through leaching.  

The report presents a literature review on the status of research related to saltwater intrusion and groundwater management in coastal and deltaic environments in the east coast of South India. The area is typically characterized by highly productive and alluvial aquifers and high use of both surface as well as groundwater. Seawater intrusion into the freshwater aquifers is extensive due to increased pumpages.

A quantitative understanding of the patterns of movement and mixing between freshwater and saline water and the factors that influence these processes is stressed in the report. It presents the mechanics of saltwater intrusion through studies by Ghyben and Herzberg and later on by Hubbert. A comprehensive review of studies by Reilly and Goodman relating to saltwater intrusion is discussed. Later advances in understanding saltwater-freshwater relationship through numerical models like sharp interface model and miscible flow model are described.

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.