Surface Water

The report attempts asymptomatic estimation of runoff curve number for small hard rock watersheds from rainfall-runoff data.One of the major activities in Applied Hydrology is the estimation of storm event runoff from ungauged small watersheds. Such estimates are often required in the design of small hydraulic structures and in formulation of watershed management strategies.

The report deals with the estimation of geomorphology parameters for small catchments using Geographical Information Systems (GIS). Stream channel morphology is literally the study of stream channel form and structure, but generally it is taken to mean their form and structures regarded as a whole or their collective morphology features. Systematic analysis of morphometry of any drainage basin and its stream system is of great importance in understanding the hydrological behavior of the basin.

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 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 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, 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.

The Soil Conservation Services Curve Number (SCS-CN) method presented in this report has been applied to two large catchments in sub-humid regions of India and its performance evaluated. The variation of the curve number is examined and discussed and a critical evaluation of the employment of the single linear reservoir routing technique and linear regression technique presented.

The report, a part of the regular work programme of the Flood Studies Division of the National Institute of Hydrology presents a literature review on modeling debris flow. Occurrence of debris flows is a common natural phenomenon and denotes the rapid flow of debris with sufficient water to disperse grains uniformly throughout the entire depth. Dam break flows, landslides and flows in a mountainous terrain are some of the examples.