Temporal evolution of precipitation-based climate change indices across India: contrast between pre- and post-1975 features

Abstract

Over the past century, extreme precipitation events have posed many problems on socio-economic status of India, a country that spans over a wide variety of climate regimes. Assessment of past changes in precipitation associated climate change indicators is very essential for effective management of the hydroclimatic risks. Present study evaluates spatio-temporal variation of eleven precipitation-based climate change indices over three 35-year epochs, i.e., 1906–1940, 1941–1975, and 1976–2010. The analysis is undertaken with the annual and monsoon season (June–September) daily precipitation data separately. Regions of significant changes are identified across the country, reflecting different characteristics (magnitude, frequency, intensity, and duration) of precipitation-based climate change indices. The results indicate a clear temporal evolution in the spatial distribution of trends over the years. During the recent epoch (1976–2010), a split is noticed with segregated increasing trends in southern region and patches of decreasing trends in northern region of the country. In contrast to the indices derived with monsoonal daily precipitation, significant trends over the country were more prominent for the indices derived with annual daily precipitation. Duration of annual maximum dry spell (wet spell) is found to significantly increase (decrease) over most of the regions. However, there is no change in total precipitation indicating an increase in short spell heavy rainfall events. The analysis and the results offer an opportunity to identify the regions of interest and to adopt revised water management policies in the future through revised water allocations, alteration of cropping pattern, etc.