The study attempts to do a space-time distribution of rainstorms associated with the tropical cyclones in the Bay of Bengal over a period of 20 years from 1976 to 1996.

The magnitude of peak flood and shape of the flood hydrograph depends not only on the magnitude of the total storm rainfall but also on its distribution in space and time. Improvements of the accuracy and timeliness of hydrological forecasting would thus largely depend on the prediction of rainfall distribution in space and time.

As the rainstorms associated with the cyclonic storms are likely to produce a somewhat different picture, which generally exceeds 24 hour and covering vast areas, it was found necessary to study this aspect in the study area, which is prone to regular cyclonic storms.

The study broadly indicated that –

• From spatial variation analysis, the heavy rainstorms which occurred over the study area during 1976-96 were identified.
• From the temporal variation analysis of the selected rainstorms in the study area, it is observed that 50 per cent of the rainfall in a storm spell occurs in 25 per cent of the storm duration and the remaining 50 per cent of the rainfall occurs in the remaining 75 per cent of the storm duration.
• From the isohyetal maps it has been observed that rainfall is concentrated in lower part of the study area and decreases towards the upstream of the river catchment.

Download the report here: