Department of Irrigation and Hydraulics Engineering, Faculty of Engineering, Tanta University, Tanta, Egypt.
Environ Sci Pollut Res Int. 2019 Sep;26(27):28228-28242. doi: 10.1007/s11356-019-06039-4. Epub 2019 Jul 31.
During the twentieth century, the intensity and frequency of extreme events (e.g., storms and floods) have significantly altered globally due to human-induced climate change. Recently, it has been recognized that some regions in Egypt have exposed to extreme rainfall events which led in some cases to severe flash floods. In this work, the variability of rainfall characteristics in Egypt was investigated based on a detailed statistical analysis of historical rainfall records at 31 stations. Both parametric (Pearson) and non-parametric (Mann-Kendall and Spearman) tests were applied on annual and seasonal precipitation indices to examine temporal trends. A classification of significant trends was introduced to assess the degrees of their likelihood. The results detected significant trends in annual indices: maximum precipitation, total precipitation, simple daily intensity index, and number of rainy days at 29, 19, 19, and 13% of stations, respectively. Significant trends in seasonal indices were also found at a few stations. For all indices, 77% of the detected significant trends are negative concluding a decrease in the amount of precipitation in Egypt. Additionally, only 6% of the detected trends are classified as less likely, while the rest is likely and extremely likely, indicating a high probability of most detected trends. Generally, the detected trends do not form any spatial pattern in all cases. The results also provided a preliminary impression on the likely impacts of climate change on rainfall characteristics in Egypt.
在二十世纪，由于人类引起的气候变化，极端事件（如风暴和洪水）的强度和频率在全球范围内发生了显著变化。最近，人们已经认识到埃及的一些地区已经暴露在极端降雨事件之下，这些事件在某些情况下导致了严重的山洪暴发。在这项工作中，根据 31 个站的历史降雨记录的详细统计分析，研究了埃及降雨特征的可变性。分别对年和季节降水指数应用参数（皮尔逊）和非参数（曼恩-肯德尔和斯皮尔曼）检验，以检查时间趋势。引入了一种显著趋势的分类方法，以评估其可能性程度。结果在 29、19、19 和 13%的站中分别检测到年指数：最大降水、总降水、简单日强度指数和雨天数的显著趋势。在少数几个站中也发现了季节指数的显著趋势。对于所有指数，检测到的显著趋势中 77%为负，表明埃及的降水量减少。此外，只有 6%的检测趋势被归类为不太可能，而其余的则是可能和极有可能，表明大多数检测到的趋势的可能性很高。总的来说，在所有情况下，检测到的趋势都没有形成任何空间模式。结果还初步说明了气候变化对埃及降雨特征的可能影响。
