Non-Stationary Analysis of Extreme Rainfall in the Karun River Basin, Iran

This study addresses the critical issue of non-stationarity in extreme rainfall events within Iran's Karun River Basin, considering global climatic shifts from ۱۹۹۵ to ۲۰۲۳. Leveraging Mann-Kendall and Sen's slope tests, the analysis revealed a significant upward trend solely in monthly maximum temperature, while precipitation and the Southern Oscillation Index (SOI) did not exhibit significant trends. To enhance modeling accuracy, stationary (SO) and non-stationary Generalized Extreme Value (GEV) models, incorporating maximum temperature and SOI as covariates, were developed for five key meteorological stations. Model selection based on the Akaike Information Criterion (AIC) indicated that a non-stationary model (NS۶), which accounts for both covariates, was superior to Ahvaz Station. In contrast, stationary models (NSO) proved more effective for Izeh, Masjedsoleyman, Safiabad (Dezful), and Shushtar. Crucially, at Ahvaz, the non-stationary model showed a drastic reduction in return periods for extreme rainfall events compared to its stationary counterpart, underscoring the vital need for non-stationary approaches to avoid underestimating future flood risks in this specific area.

کلیدواژه ها:

Extreme rainfall ، Karun River Basin ، Modified Mann-Kendall ، Nonstationary Assessment