Observations and climate models confirm precipitation pattern is changing over Nepal

Abstract

This paper presents a comprehensive picture of precipitation variability across Nepal over the present (1985-2014) and future (2021-2050) based on gauge-based observations from 28 precipitation stations distributed throughout the country and thirteen climate models of the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) under two Shared Socioeconomic Pathways (SSP 245 and SSP 585). Seventeen different precipitation indices are computed using daily precipitation data based on gauge-based observations and climate models. Along with absolute extreme precipitation indices, such as maximum 1-day, maximum consecutive 3-day, 5-day, and 7-day precipitation amounts, this study also computes the contribution of such instances to the annual precipitation. The selected precipitation indices not only allow for the analyses of heavy precipitation-related extremes but also guide the evaluation of agricultural productivity and drought indications, such as consecutive dry and wet days (CDD and CWD). The number of wet days and average precipitation during those wet days, along with the information of the number of days with daily precipitation ≥ 10, 20, 50, and 100 mm, summarize the distribution of total precipitation. This study emphasizes changing precipitation patterns by looking at these indices over the present and future periods. Observations and climate models show a changing nature of precipitation over Nepal. However, different climate models exhibit a different severity of changes. Though the yearly precipitation amount is not altered noticeably, this study finds that the extremes are expected to alter significantly than the averages. It is also to be noted that climate models are unable to capture localized extremes in Nepal Himalayas.

An outlook on the applicability of satellite precipitation products for monitoring extreme precipitation events in Nepal Himalaya

“…These performance metrics were computed as follows: The lower the error value, the better the performance is for all four magnitude‐based metrics. In this study, we also computed 17 extreme precipitation indices (Talchabhadel, 2021) on an annual scale that included consecutive dry and wet days (CDD and CWD), number of wet days (R1, i.e. number of days when daily rainfall ≥1mm), total rainfall amount (PRCPTOT), simple daily rainfall intensity index (SDII), number of days when daily rainfall ≥10, 20, 50, and 100mm (R10, R20, R50, and R100), maximum one‐day precipitation amount (RX1day), maximum consecutive three‐days, five‐days, and seven‐days (RX3day, RX5day, and RX7day), and percentage contribution of RX1day, RX3day, RX5day, and RX7day to the PRCPTOT [i.e.…”

Integrated modeling for assessing climate change impacts on water resources and hydropower potential in the Himalayas

“…The largest range of increment for subbasin level precipitation varying from 32 to 72% is projected for the SSP 585 scenario in the far future. Talchabhadel (2021) found a positive deviation in future annual precipitation in 28 weather stations across…”

“…We select six climate models: (1) ACCESS-CM2, (2) ACCESS-ESM1-5, (3) EC-Earth3, (4) EC-Earth3-Veg, (5) MPI-ESM1-2HR, and (6) MRI-ESM2-0 (refer Supplementary Table S2 for details) under two SSPs (i.e., SSP 245 and SSP 585). These climate models and scenarios are selected since they demonstrate improved reliability and a range of likely scenarios from medium to the highest warming pathways and an intermediate to the highest socioeconomic challenges across the Himalayan river basins (Mishra et al 2020b;Talchabhadel 2021).…”

Evolution and future prospects of hydropower sector in Nepal: A review

“…Investing hydrocarbon revenues into modernizing agriculture can also enhance productivity and strengthen food security [ 30 ]. With climate change threatening Nepal's seasonality and precipitation patterns [ 31 ], efficiently harnessing water resources through hydropower projects with storage capacity provides a buffer against droughts or variability in crop yields. Thus, strategic development of hydroelectricity and investment of energy revenues represents a pathway for improving resource sustainability and resilience of rural food systems as Nepal continues to advance economically.…”