Future precipitation extremes over base Himalayan Uttarakhand region: analysis using the statistically downscaled, bias‑corrected high‑resolution NEX‑GDDP datasets

Abstract

The Himalayan region of Uttarakhand, India, has witnessed floods and landslides, and more extremes are likely in the future. This study examined the projected changes in precipitation extremes by using state-of-the-art, high-resolution (0.25° × 0.25°) statistically downscaled NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) during southwest monsoon season (June to September) under the RCP 4.5 and RCP 8.5 scenarios. The spatial variations of mean precipitation, as well as the extremes obtained from the multi-model mean (MMM) from NEX-GDDP simulations, were compared with Asian Precipitation-Highly-Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE) observational data for the baseline period (1976–2005). For the future climate, the monsoon precipitation over the Uttarakhand region may increase by ~ 13% and ~ 16% under the RCP 4.5 and RCP 8.5 emission scenarios, respectively, in the near future (2021–2050) and may further increase by 23% and 36% in the far future (2070–2099). The different extreme precipitation indices analyzed show an increase with the exception of consecutive dry days (CDDs) over Uttarakhand, both in the near future and in the far future, under both scenarios. The RCP 4.5 and RCP 8.5 scenarios exhibited a noticeable increase in the highest 1-day rainfall (by 1.4 mm decade−1 and 3.3 mm decade−1) and in the highest 5-day rainfall (by 2.7 mm decade−1 and 7 mm decade−1), along with the extreme R95P precipitation days (by 11% and 22%), and consecutive wet days become more frequent during monsoon season, respectively. The study findings highlight the need for considering more extreme rains in base Himalayan climate resiliency planning.