Rainfall and other forms of Precipitation

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.

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.

The report deals with expert systems for unit hydrograph analysis, an emerging technology, which may in years to come, revolutionize professional activities in the field of surface water analysis and modeling. The literature review on the topic revealed the potential of application of expert system for unit hydrograph analysis. A prototype expert system has been developed for the selection of the most appropriate model for unit hydrograph derivation of a given catchment.

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.

The report deals with software developed by the National Institute of Hydrology with the purpose of preparation of hydrological data book in a form most valuable to the users. A menu driven, user friendly software has been developed to handle all types of hydrological and meteorological data.

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.

Article Courtesy : Reuters AlertNet
Written by: Nita Bhalla

NEW DELHI (AlertNet) - Floods triggered by heavy monsoon rains have killed more than 50 people and displaced almost half a million more in India's south and northeast, say government officials.

Overflowing rivers and reservoirs have inundated low-lying villages mainly in India's oil and tea-rich state of Assam, but also on the opposite side of country in the southwestern coastal state of Kerala.

Flood-affected people sit in a damaged hut
as they wait for relief supplies in Lakhimpur
district, in India's northeastern state of Assam.
FILE PHOTO, July 2009. REUTERS/Stringer

According to the ministry of home affairs, almost one million people have been hit by the floods, forcing almost half a million to leave their water-logged villages and seek shelter in government relief camps.

Mountainous Assam, where five people have drowned, has been the worst-affected with 13 out of 27 districts hit by flooding, including Kokrajhar, Lakhimpur, Baksa and Bongaigaon.

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.

The study aims to assess the impacts of various climate scenarios on the hydrological response of the high altitude Spiti river in the Himalayas. The climatic scenarios were constructed on the basis of simulations of the Hamburg coupled atmosphere-ocean climate model for the study region.

The report gives an account of a feasibility study of rainwater harvesting in semi-arid regions. A review of water harvesting systems is followed by a section wherein numerical solutions for surface flow equations are explained.