Future Changes on Hydrological Extremes in High Mountain Asia

Changes in High Mountain Asia (HMA) water resources affect the livelihood of more than a billion people and have an impact on the biodiversity of the unique ecosystems of the region. Hydrological extremes (such as floods and droughts) have significant impact on the quality and availability of water resources and the sustainability of the natural environment, with important consequences on the economic growth in the region. Therefore, understanding and quantifying future changes in hydroclimatic risk is necessary to inform long- term policy and investment decisions of policymakers, industry, and the general public. Given the high complexity of the land surface characteristics and the meteorological and hydrological processes in HMA, one needs to utilize information at high spatial resolution to allow accurate representation of the spatial variability of meteorological and hydrological processes and to properly analyze changes in extremes. To address this issue in this work, we take advantage of recent state-of-the-art climate dataset developed as part of the NASA High Mountain Asia program. Specifically, we analyze historic and future climate data (CMIP6, scenarios SSP2-4.5 and SSP5-8.5) of daily precipitation and temperature downscaled at high spatial resolution (5km) and quantify the changes in characteristics of extreme precipitation and drought in HMA. Changes in the frequency and severity of both droughts and precipitation extremes are mapped across the various topographic and climatic gradients of the region and "hotspots" of change are identified. Results on projected changes in extremes under different emission scenarios are expected to provide important information in the region for climate adaptation decisions and planning.