19 Jul 2023
 | 19 Jul 2023
Status: this preprint is currently under review for the journal HESS.

Employing the Generalized Pareto Distribution to Analyze Extreme Rainfall Events on Consecutive Rainy Days in Thailand's Chi Watershed: Implications for Flood Management

Tossapol Phoophiwfa, Prapawan Chomphuwiset, Thanawan Prahadchai, Jeong-Soo Park, Arthit Apichottanakul, Watchara Theppang, and Piyapatr Busababodhin

Abstract. Extreme rainfall events in the Chi watershed of Thailand have significant implications for the safe and economic design of engineered structures and effective reservoir management. This study investigates the characteristics of extreme rainfall events in the Chi watershed, Northeast Thailand, and their implications for flood risk management. We apply extreme value theory to historical maximum cumulative rainfall data for consecutive rainy days from 1984 to 2018. The Generalized Pareto Distribution (GPD) was used to model the extreme rainfall data, with the parameters estimated using Maximum Likelihood Estimator (MLE) and Linear Moment Estimator (L-ME) methods based on specific conditions. The goodness-of-fit tests confirm the suitability of the GPD for the data, with p-values exceeding 0.05. Our findings reveal that certain regions, notably Udon Thani, Chaiyaphum, Maha Sarakham, Tha Phra Agromet, Roi Et, and Sisaket provinces, show the highest return levels for consecutive 2-day (CONS-2) and 3-day (CONS-3) rainfall. These results underscore the heightened risk of flash flooding in these regions, even with short periods of continuous rainfall. Based on our findings, we developed 2D return level maps using the Q-geographic information system (Q-GIS) program, providing a visual tool to assist with flood risk management. The study offers valuable insights for designing effective flood management strategies and highlights the need for considering extreme rainfall events in water management and planning. Future research could extend our findings through spatial correlation analysis and the use of copula functions. Overall, this study emphasizes the importance of preparing for extreme rainfall events, particularly in the era of climate change, to mitigate potential flood-related damage.

Tossapol Phoophiwfa et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-167', Anonymous Referee #1, 25 Sep 2023 reply
    • AC1: 'Reply on RC1', Piyapatr Busababodhin, 27 Sep 2023 reply

Tossapol Phoophiwfa et al.

Tossapol Phoophiwfa et al.


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Short summary
This study examines the impact of extreme rainfall events in Thailand's Chi watershed on flood risk management. By analyzing historical data, we identified regions, notably Udon Thani and Chaiyaphum, with a high risk of flash flooding. To aid in flood risk assessment, visual maps were created. The study underscores the importance of preparing for extreme rainfall events, particularly in the context of climate change, to effectively mitigate potential flood damage.