A century scale hydro-climatic variability and associated risk in Subarnarekha river basin of India

摘要

Assessment of risk caused by extreme rain plays a significant role in the management of water resources for the tropical region of India, which is solely dependent on the monsoon rainfall. In the present paper, a century scale characterisation of hydro-meteorological parameters is done to evaluate fluctuations, climatological features, long-term trend, periodicity, and sensitivity of water-balance parameters to temperature change in the Subarnarekha basin of the Eastern Gangetic plains of India. Theory of extreme value is applied to characterize risk of the extreme events in the basin. A long-term prediction of the behavior of extreme rain events is performed. At seasonal, annual, and monthly scales, it is observed that there is no long-term trend in the rainfall. Short-term fluctuations dominate the total variance of annual rainfall, which is of less than 10 years. Percentage change of water-balance parameters (actual evapotranspiration, surplus, and precipitation) AE/P and S/P are highly sensibleto temperature change. Subarnarekha basin is found to be highly susceptible to extreme rainfall event with a 20 year return level of 163 mm daily rainfall.