National Institute of Hydrology

The study attempts to do field and laboratory determination of soil classification properties in the Dudhnai river basin of Assam and Meghalaya. Point infiltration tests using double ring infiltrometer were conducted at various locations (forty-four sites) in respect of different land use conditions. Soil samples were collected from these infiltration testing sites.

The saturated hydraulic conductivity was determined in the field using Guelph Permeameter for the selected sites. The undisturbed soil samples and disturbed soil samples (50 cm below the ground) were collected and subjected to elaborate laboratory tests. 

The study was taken up as a part of the representative basin studies being done by NIH and involved hydrological land use & land cover mapping for the Suddagedda basin of Andhra Pradesh. Mapping was carried out through visual interpretation for the years December 1987, April 1989, December 1992 and November 1996 using IRS IB-LISS II, LANDSAT 5-TM and IRS IC-LISS III data.

Land use and land cover are the most important surface characteristics of a basin. They are very dynamic features over space and time and it is difficult to get real time information on them through conventional means. Planners need to update knowledge of natural resources, which can be obtained quickly, economically and accurately through remote sensing techniques. Further, the land use map of a basin or region provides hydrologically significant categories, which are essential for estimation of reliable runoff from ungauged basins.

The study attempts to find out the effects of geomorphology on watershed runoff response in the Devak basin and tries to identify the parameters that are more closely related to runoff. A chief objective of the study is to regionalize the hydrologic models describing the rainfall-runoff process. 

The advanced knowledge of geomorphology of the region is of importance in the field of flood control measures and engineering projects, since geomorphological characteristics of river basins in mountainous areas affect runoff processes and formation of floods in the areas.

The study undertakes hydrological soil classification of Suddagedda basin of Andhra Pradesh based on field and laboratory experiments on the soil samples. The hydrologic soil properties of an area are essential to accurately estimate the runoff generated due to storm in the area. The main soil parameters generally considered for analysis are soil texture, soil structure, infiltration rate and hydraulic conductivity.

The study develops a regional conceptual catchment water balance model for five catchments in the Western Ghat region of Karnataka. The model can be used to estimate the water yield from ungauged catchments located in the region.

The water yield is an integration of discharge as a function of time for a specified duration and reflects the volumetric relationship between rainfall and runoff. The estimation of water yield is required for solution of water resources problems normally encountered in design of storage facilities. It is of use in understanding the water availability for agriculture, industrial and drinking purpose as also for estimating the dependable water supply for power generation and irrigation projects.

The study uses HEC-RAS to analyse the water surface profiles of Malaprabha river system upto Khanapur for different combinations of discharges through various reaches of the river system. The river system is divided into eleven reaches, and forty one cross sections have been measured and interpolated within these reaches.

Discharge values have been assigned for different reaches according to the ratio of contributing area for each reach. The bridge across the river at Khanapur is reproduced in the modeling system to test its capabilities. Various return period floods have been allowed to pass through the river system to compute the individual water surface profiles.

The study attempts to quantify geomorphological characteristics, generate various thematic databases in Geographic Information Systems (GIS) format and derive landuse information using remote sensing digital data for the Danda watershed in the Tehri-Garhwal district of Uttarakhand. Based on these it develops a land capability classification and generates alternate land use plan.

An integrated approach is followed wherein remote sensing and Geographical Information systems (GIS) techniques have been utilized for evaluation of the catchment characteristics such as geomorphology, landuse, soil and slope. The linking of the geomorphological parameters with the hydrological characteristics of the basin provides a simple way to understand the hydrologic behavior of the basin.

The study evaluates groundwater on the basis of widely used graphical methods like Piper, Stiff and US Salinity Laboratory classification. The study concludes that, in general, the groundwater in the area varies from medium salinity to very high salinity, the latter being more common in the irrigated stretches. The irrigators are advised to ensure good land and water management practices in the fields, with particular emphasis on creating favorable leaching and drainage conditions to avoid further development of saline conditions in the area. 

The study develops a relationship between suspended sediment load and discharge for three basins - Kasol, Suni and Lower Satluj. The sediment load (tonnes/ year) and sediment yield (tonnes/ sqkm/ year) in suspension and as bed load of sand & gravel through the river channel, reflects upland erosion in the drainage basin and deposition of sediments in the alluvial bottomlands. A good deal of the sediment eroded from upland areas is deposited on lower hills slopes, in bottomlands, lakes and reservoirs.

The study aims to establish relationship between spectral reflectance of rice canopy, crop growth, chlorophyll concentrations and water use. Two fields were chosen for radiometric and agronomic measurements over the period from flowering to maturity (August to November).