Changing Pattern of Intensity–Duration–Frequency Relationship of Precipitation due to Climate Change.

Intensification of hydrologic cycle, and consequence rise of intense short-term precipitation, are considered as the manifestations of climate change. This may lead to an alteration in Intensity–Duration–Frequency (IDF) relationship that may change other hydrological processes as well. The IDF relationship also serves as a crucial information for the design of any water infrastructure. This study investigates the spatiotemporal changes in IDF relationship involving hourly precipitation events between past and future climate at various return periods across India that spans over a wide range of climatology. Contrast between historical (1979–2014), using two reanalysis data, and future periods (immediate future: 2015–2039, near-future: 2040–2059 and far-future: 2060–2100) is explored along with its spatial (re-) distribution. The future simulations of precipitation are derived from three climate models, participating in 6^th phase of Coupled Model Intercomparison Project (CMIP6), for three shared socio-economic pathways (SSPs), i.e., SSP126, SSP245 and SSP585. The results show that almost entire Indian mainland will experience an increase (~41–44%) in the hourly precipitation intensity under the worst climate change scenario (SSP585) with a return period as low as 2 years (almost a regular incidence). Furthermore, even under a moderate climate change scenario (SSP245), almost entire Indian mainland (~82–99% of spatial extent) will be affected from a significant increase (on an average 19%) in the hourly precipitation intensity. It is true for higher return periods as well. Findings of the study are alarming for many water infrastructures. This study develops new set of IDF curves across India considering a changing climate that will be useful to set a revised design criteria for water infrastructure. [ABSTRACT FROM AUTHOR]