Due to a continuous increase in global temperature, the climate has been changing without sign of alleviation. An increase in the air temperature has caused changes in the hydrologic cycle, which have been followed by several emergencies of natural extreme events around the world. Thailand is one of the countries that has incurred a huge loss in assets and lives from the extreme flood and drought events, especially in the northern part. Therefore, the purpose of this study was to assess the hydrological regime in the Yom and Nan River basins, affected by climate change as well as the possibility of extreme floods and droughts. The hydrological processes of the study areas were generated via the physically-based hydrological model, namely the Soil and Water Assessment Tool (SWAT) model. The projected climate conditions were dependent on the outputs of the Global Climate Models (GCMs) as the Representative Concentration Pathways (RCPs) 2.6 and 8.5 between 2021 and 2095. Results show that the average air temperature, annual rainfall, and annual runoff will be significantly increased in the intermediate future (2046–2070) onwards, especially under RCP 8.5. According to the Flow Duration Curve and return period of peak discharge, there are fluctuating trends in the occurrence of extreme floods and drought events under RCP 2.6 from the future (2021–2045) to the far future (2071–2095). However, under RCP 8.5, the extreme flood and drought events seem to be more severe. The probability of extreme flood remains constant from the reference period to the near future, then rises dramatically in the intermediate and the far future. The intensity of extreme droughts will be increased in the near future and decreased in the intermediate future due to high annual rainfall, then tending to have an upward trend in the far future.

中文翻译：

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泰国Yom和Nan流域气候变化下的极端水文气候事件预测

由于全球温度的持续升高，气候变化没有缓解的迹象。气温升高导致水文循环发生变化，随后世界各地发生了几次自然极端事件的紧急情况。泰国是遭受极端洪水和干旱事件（尤其是北部地区）的巨大资产和生命损失的国家之一。因此，本研究的目的是评估受气候变化以及极端洪涝和干旱影响的赎罪日和南江流域的水文状况。研究区域的水文过程是通过基于物理的水文模型，即土壤和水评估工具（SWAT）模型生成的。预计的气候条件取决于全球气候模式（GCM）的输出，作为2021年至2095年之间的代表浓度路径（RCP）2.6和8.5。结果表明，平均气温，年降雨量和年径流量将显着增加。在中期（2046年至2070年）以后，尤其是在RCP 8.5下，这种情况有所增加。根据流量持续时间曲线和峰值流量恢复期，从未来（2021-2045）到远期（2071-2095），在RCP 2.6下，极端洪水和干旱事件的发生都有变化的趋势。但是，在RCP 8.5下，极端的洪水和干旱事件似乎更为严重。从参考期到不久的将来，极端洪灾的可能性保持恒定，然后在中期和遥远的将来急剧上升。