Rivers

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.

In this study, an attempt has been made to develop a regional flood formula using L-moments for the north Brahmaputra river system. The annual maximum peak flood data of twelve gauging sites of the north bank tributaries of the river have been considered. The screening of the data has been carried out for assessing the suitability of the data for regional flood frequency analysis by computing the Discordancy Measure (Di) in terms of L-moments. Also, homogeneity of the region has been tested using the L-moment based heterogeneity measure, H.

The study evaluates the applicability of Artificial Neural Networks (ANN) in rainfall-runoff process modeling for the Ajay river basin, Jharkhand to predict the 6-hour ahead runoff at Sarath. Initially three flood events were considered for training, to find out the weights between different layers of the network. The back propagation algorithm has been used for optimization of weights. The developed ANN was validated for rest of the flood events.

In the present study, two different Artificial Neural Networks (ANN) were developed for Dharoi reservoir, Gujarat, one for flood control operation and another for conservation operation. In recent years, ANNs are increasingly being used to predict water resources variables particularly in the operation of reservoirs, the most important elements of complex water resources systems, constructed for spatial and temporal distribution of water.

The report presents a sedimentation study in which sedimentation rate and volume have been determined using remote sensing data in the Ukai reservoir constructed across the Tapti River in Gujarat.

We have adopted the metric system long back (1957) and there was a grace period of 10 years for transition from British units to metric units.

The report presents the effect of non hydrostatic pressure distribution on dam break flood wave movement. Dam break flood moves with non-hydrostatic pressure distribution in the vertical direction. However, almost all the mathematical models for dam break flows use Saint-Venant equation, which presume hydrostatic pressure in the vertical direction. In this report, an attempt has been made to use Boussinesq equations in the mathematical model. 

The report examines the effect of periodicity in the rainfall records on the water availability of Damanganga basin in Nasik and Thane districts of Maharashtra. Based on the rainfall-runoff record of a shorter period, runoff series for a longer period is developed using a water balance model. The per cent deviation in water availability estimations computed using short term wet and dry records from the complete records is examined. The effect of length of time-series on the water availability estimates is also studied.

In this report, a mathematical model capable of computing the flow depth and discharge in each of the branched flows is developed using gradually varied flow equations. This model can handle three flow situations viz. temporary flow diversion, a cut-off channel and a single river island. Computational capability of the model is increased to handle irregular cross sections of a river.