National Institute of Hydrology

In this report an attempt has been made to estimate the mean monthly reference crop evapotranspiration (ETo) for the Krishnai Irrigation Project in Assam. To undertake this analysis, the mean monthly climatological and physiographical data for the period of 1986 to 1994 has been collected from the Meteorological Department, Borjhar, Assam.

The report deals with the transportation behavior of lindane, a pesticide used commonly in the agricultural and public health sectors in India, through sandy and loamy soils. The contamination of groundwater by pesticides is a worldwide problem because of their tissue degradation and carcinogenic nature. They are bio-accumulative and relatively stable and therefore, require close monitoring.

The pesticides used for agricultural, forestry and domestic activities leach into the groundwater and therefore, it is very important to study their transportation behavior in different types of soil media.

The study deals with the distribution of heavy metals on sediments under different flow conditions in the river Hindon. The river is subjected to varying degree of pollution caused by numerous untreated waste outfalls of municipal and industrial effluents.

The report deals with development of reaeration coefficient for Indian condition using mathematical approach and field studies. Of the various constituents, which determine the quality of water, Dissolved Oxygen is the most important parameter indicating the health of a stream. There is a continual replenishment (reaeration) or utilization (deoxygenated) of Dissolved Oxygen due to inflow of waste load at different points in the stream. When a waste load is discharged into a flowing stream, it is mainly subjected to advection, dispersion and reaction kinetics. Waste Load Allocation (WLA) studies provide information to assist in making effective decisions on levels of treatment required for a source or sources of pollutant loads.

The report attempts drought characterization in arid and semi-arid climatic regions of India. Drought frequency and intensity are a function of the dimensionless climatic parameter derived as a ratio of mean annual potential evapotranspiration to mean annual precipitation (Ep/Pa).

The report presents a study on the Sagar lake wherein the various water balance components like inputs and outputs have been quantified to visualize the influence of these parameters on the storage changes. Lakes play an important role in shaping the hydrological, ecological and environmental balance of the region by developing the flora, fauna and habitation of the aquatic biota. Like other lakes, Sagar lake too faces manifold problems of siltation and deterioration of water quality, thus threatening its survival.

The report presents an inventory of water bodies in the State of Jammu & Kashmir in the Western Himalayan region prepared using satellite data of IRS-1A (standard FCC, scale 1:250000) for 1988/ 99 and digital data of IRS-1C for 1998. Also, presented is a database developed with the help of Survey of India (SoI) topographic maps, which includes name and type of the water body, nearest place, district, river basin, geographical coordinates and elevation.

The report presents the status of the sediment studies carried out in the lower as well as higher altitude region of the Garhwal Himalayas. The processes associated with sediment production in the mountainous region have been described with an emphasis on the glaciarized region. Suspended sediment concentration and load observed in the Dokraini glacier melt stream near its snout has been computed.

In this study, regional flood frequency relationships have been developed using L-moments for South Bihar, in the alluvial plains of Indo-Gangetic basin and Kaimur-Chhotanagpur Santhal Pargana plateau. The annual maximum peak flood data of twenty-two gauging sites whose catchment areas vary from 11.7 to 3171 sqkm have been used. The mean annual peak floods of these sites vary from 29.15 cumec to 1293.2 cumec. Comparative regional flood frequency analysis studies have been carried out using some of the commonly used frequency distributions viz Extreme Value (EV1), General Extreme Value (GEV), Normal, Log Pareto (GPA) and Wakeby based on L-moments approach.

In this study, the mathematical model developed at the National Institute of Hydrology for estimation of the Clark model parameters using the geomorphological characteristics of an ungauged basin has been applied for simulation of the direct surface runoff (DSRO) hydrographs of the Ajay basin up to the Sarath gauging site of South Bihar.