Changes in climate extremes over major river basins of India

Temporal changes in the extreme rainfall and temperature characteristics of major river basins on a daily time scale are examined using high-resolution gridded daily rainfall (1951-2014) and temperature (1951-2013) data sets. Trend analysis is carried out to examine the temporal changes in the frequency, area covered and intensity of the extreme rainfall and temperature events. Rainfall of 10cm during southwest monsoon season (JJAS), maximum temperature of 40 degrees C during summer season (MAM) and minimum temperature of 10 degrees C during the winter season (DJF) have been used as the thresholds to define the extreme weather events of rainfall and temperature data in these river basins. Analysis indicates that during monsoon season zero rainfall days are increasing in all the river basins except some parts of the Krishna and Peninsular river basins. River basins located in the central parts of India show significant increase in the area covered by the heavy rainfall episodes and their intensity. Substantial rise in the monthly maximum temperatures is seen in the Krishna, Peninsular and West Coast river basins. Frequency, area coverage and intensity of hot days during summer season are increasing significantly in the Krishna and Peninsular river basins, while no substantial change has been observed for cold days during winter season in any river basins of the study.