Increase in probable maximum precipitation in a changing climate over India

Probable Maximum Precipitation (PMP) is considered as an important design criteria and it is expected to change over time owing to the impacts of climate change and intensification of global hydrological cycle. Thus, reconstruction of PMP map and investigation about its temporal change are very essential in the context of climate change. This study develops 1-day PMP map of India for five consecutive time periods (two in historical, i.e., 1901-70, 1971-2010; and three in future, i.e., 2010-39, 2040-69 and 2070-2100) to study its temporal change. Observed gridded daily precipitation data from India Meteorological Department (IMD) and outputs from three climate models following two Representative Concentration Pathways (RCPs) are used to develop historical and future PMP maps, respectively. The modified Hershfield method is used for estimation of PMP with an updated method for enveloping technique. The results show a clear increasing trend in PMP for most part of India. Specifically, 84% area of Indian mainland exhibits an increasing trend in PMP with an average of around 35% increase in post-1970 (1971-2010) period as compared to pre-1970 (1901-1970) period. Similarly, in the farfuture period (2071-2100), around 70-80% area is showing an increase with an approximate average increase of 20%-35% in PMP across different models with respect to recent past (1971-2010) following RCP 8.5 scenario. These observations evidently indicate how significantly PMP is increasing due to climate change and it should be considered in the revised planning and design in water resources engineering.