Spatial and temporal rainfall changes in Egypt.

Abstract

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.