Rivers

The study attempts to develop a computerized model for Geomorphological Instantaneous Unit Hydrograph (GIUH) for estimation of flood hydrographs resulting from intermittent storms of varying intensity. The model applied to the rainfall-runoff data of the Myntdu-Leska basin of Meghalaya infers that the channel network and geomorphological features are closely related to the retention and discharge characteristics of the basin.

The theory of GIUH assumes that rainfall that occurs over a basin is assumed to be composed of infinite number of non-interacting drops of uniform size. After spending some time in one state in the channel or overland region, the drop makes transitions to another state to reach the basin outlet. Assuming one parameter, exponential time distribution of one drop chosen at random from the basin defines the IUH of the basin.

The study gives a systematic methodology to determine field hydraulic conductivity using Guelph Permeameter (GP), its limitation based on the experiences gained in the field and a comparison of its results with that estimated from the predictive method for the soils in Central Bihar. Predictive methods applying empirical formulae are used to ascertain hydraulic conductivity from easily determined factors like bulk density, porosity and water content.

Physically based hydrological models, soil water balance, groundwater flow and transport models require values of saturated and unsaturated hydraulic conductivity to solve the sub-surface flow and transport equations. Several field, laboratory and predictive methods are available for determination of this parameter. However, these methods have some advantages and some limitations. GP is used as a tool to determine the field hydraulic conductivity even when the water table is low. It is portable, durable and allows rapid field calculation of saturated and unsaturated hydraulic conductivity.

The study estimates the average soil loss using the Geographic Information Systems (GIS) tool of Integrated Land and Water Information Systems (ILWIS) and the Universal Soil Loss Equation (USLE) methodology for the Hire nadi catchment, in Yelbarga taluk, Koppal district of Karnataka, under different conditions.  

Scientific planning for soil conservation and water management requires knowledge of the relations among factors that cause and prevent soil and water loss.  Controlled studies on field plots and small watersheds have supplied vital information regarding these complex factors and their interrelations.

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 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 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 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 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.  

The study uses remote sensing data to develop a land use classification and applies statistical methods appropriate for Indian catchments to estimate the annual sediment load from the Upper Indravati catchment in Orissa for the year 2000. The study points to the fact that assessment of reservoir catchment regions at regular intervals would enhance the understanding of the geodynamic processes and help in identifying effective control measures.

The study models the variations in water quality parameters of Yamuna river by means of stochastic approach using Central Water Commission’s monthly data for the period 1990-95 and makes projections for the year 1996. The results obtained for different water quality variables have been compared with the observed values and were found to be satisfactory.