Observations and climate models confirm extreme precipitation events are happening more often and the magnitude increases significantly
Abstract
This paper presents a comprehensive picture of extreme precipitation across Nepal over the present (1986 - 2015) and future (2021 - 2050) based on ground based high-quality daily precipitation observations from 28 precipitation stations distributed across Nepal for 30 years each during the present and future periods. We used a total of 13 CMIP6-GCMs (sixth phase of the Coupled Model Intercomparison Project - Global Climate Models), and ensemble of selected best-performed climate models for projected analysis under two scenarios biz. SSP 245 and SSP 585 developed by Mishra et. al (2020) at 0.25° spatial resolution for South Asia. Along with popular extreme precipitation indices, four additional ratio-based indices were computed. Percentage contributions of maximum one-day, consecutive 3-day, 5-day, and 7-day (RX1day, RX3day, RX5day, and RX7day respectively) to the annual precipitation (PRCPTOT) provide the information on the severity of extremeness of precipitation distribution during the year. The selected indices not only allow for analyses of heavy precipitation related extreme events such as flood/inundation producing precipitation events and amounts, but also for the evaluations of agricultural production and drought indicators such as consecutive dry and wet days (CDD and CWD) on a seasonal and annual scales.
In addition, a simple daily intensity index (SDII) and count of days with daily precipitation ≥ 10 mm (R10), ≥ 20 mm (R20), ≥ 50 mm (R50), and ≥ 100 mm (R100) summarize the distribution of the wet part of the year at different locations. This study emphasizes on changes of those indices attributed between the present and future periods across the country. Our results showed though the amount of precipitation (in terms of PRCPTOT, and SDII) was not significantly altered between two periods (i.e. present and future). However, a clear increasing trend of heavy precipitation related indices was observed in the future period compared to the present period. CDDs showed a similar rising tendency during both periods indicating the coming days will have even adverse effects in plant/crop growth. The study, therefore, recommends for effective management of precipitation extremes on both ends (i.e. drier and wetter), for instance by introducing irrigation facilities and flood mitigation measures.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA042.0011T
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 3354 Precipitation;
- ATMOSPHERIC PROCESSES;
- 1854 Precipitation;
- HYDROLOGY;
- 4313 Extreme events;
- NATURAL HAZARDS