Flood and drought are natural phenomena whose probability of occurrence increases with changing weather conditions. Climate change has affected the hydrologic cycle's parameters and led to changes in temperature and precipitation pattern, which may increase the probability of occurrence of floods and droughts. Arid and semi-arid areas are subject to extreme weather conditions and water resources scarcity. This study aims to assess drought and flood in Syria using remote sensing data. Monthly precipitation data have been collected from 10 land stations in the western part of Syria for the period (1991–2009) and satellite images for monthly precipitation from 1983 to 2020 were collected. The land stations data were used to correct the satellite images and correction equation was developed for each station. Standardized Precipitation Index (SPI) is used for analysis of drought and flood. Also, the main parameters for drought and flood, severity, intensity, duration, and the average return time were estimated. The results showed extreme flood events were recorded in 1988, 2002, 2012, and 2019 and extreme drought events were recorded in 1990, 2014, and 2016. The highest severity of drought and flood were recorded in 2014 and 1988 respectively. However, the highest intensity of droughts and floods was recorded in 2016 and 1988, respectively. If land station data are unavailable, as in the case of Syria owing to the protracted war, satellite images may be a useful source of data for drought and flood analysis after correction. This methodology can help in drought/flood analysis and estimate severity, intensity, duration, and the average return time of flood and drought in other locations of the world. The results proved that SPI is a useful tool to predict the time of occurrence of both flood and drought that could help decision-makers for putting efficient plans for flood and drought risk management that could mitigate the impacts of such risks.

中文翻译：

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利用遥感数据和标准化降水指数监测干旱和半干旱地区的洪涝和干旱风险：以叙利亚为例

洪水和干旱是自然现象，其发生的可能性随着天气条件的变化而增加。气候变化影响了水文循环参数，导致气温和降水格局发生变化，可能增加洪涝和干旱发生的概率。干旱和半干旱地区面临极端天气条件和水资源短缺。本研究旨在利用遥感数据评估叙利亚的干旱和洪水。从叙利亚西部的 10 个陆地站收集了 1991 年至 2009 年期间的月降水量数据，并收集了 1983 年至 2020 年月降水量的卫星图像。陆地站数据用于校正卫星图像，并为每个站开发校正方程。标准化降水指数（SPI）用于分析干旱和洪水。此外，还估计了干旱和洪水的主要参数、严重程度、强度、持续时间和平均重现时间。结果显示，极端洪水事件发生在1988年、2002年、2012年和2019年，极端干旱事件发生在1990年、2014年和2016年。干旱和洪水最严重的年份分别是2014年和1988年。然而，干旱和洪水强度最高的年份分别是2016年和1988年。如果无法获得陆地站数据，例如由于旷日持久的战争而导致叙利亚的情况，卫星图像经过校正后可能是干旱和洪水分析的有用数据来源。该方法可以帮助进行干旱/洪水分析，并估计世界其他地区洪水和干旱的严重程度、强度、持续时间以及平均重现时间。结果证明，SPI 是预测洪水和干旱发生时间的有用工具，可以帮助决策者制定有效的洪水和干旱风险管理计划，从而减轻此类风险的影响。