Digital surface models, land use and rainfall data were used to simulate water areas using Hydrologic Engineering Centres River Analysis System (HEC‐RAS) software. Multi‐temporal synthetic aperture radar (SAR) was used for the detection of flood prone area to calibrate HEC‐RAS, due to the lack of data validation in the New Cairo City, Egypt. The thresholding water detection method was applied to two Sentinel‐1 images, one pre‐ and one post‐flash flood event from April 24 to 27, 2018. The threshold method was used to detect water areas from SAR Sentinel‐1 images. Feature statistical agreement F₁ and F₂ values ranged from 73.4 to 77.7% between water areas extracted based on backscattering values between 19.97 and 16.53 in decibels (dB) and reference water areas obtained using an optical image of the Sentinel‐2 satellite. The similarity between simulated HEC‐RAS two‐dimensional (2D) of water areas and reference water areas based on SAR data ranged between 74.2 and 89.7% using feature statistical agreement values F₁ and F₂. It provides a clear suggestion that, in the absence of field observations, SAR data can be used to calibrate the model. Two flood hazard maps created based on water velocity and depth were obtained from HEC‐RAS 2D simulation. The obtained maps indicated that 11% of the roads and 50% of the buildings in New Cairo City are exposed to high hazard areas. Furthermore, 28% of the bare land is situated in a very high vulnerability area. We recommend the use of obtained hazard map in supporting emergency response, and designing effective emergency plans.

中文翻译：

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Sentinel-1遥感数据和水文工程中心的河流分析系统二维集成，用于埃及新开罗市的山洪暴发检测和建模

使用水文工程中心河流分析系统（HEC‐RAS）软件，使用数字地面模型，土地利用和降雨数据来模拟水域。由于埃及新开罗市缺乏数据验证，多时合成孔径雷达（SAR）用于检测易发洪水区域以校准HEC-RAS。将阈值水检测方法应用于2018年4月24日至27日的两张Sentinel-1图像，一次洪灾前事件和一次闪光灯后洪水事件。阈值方法用于从SAR Sentinel-1图像中检测水域。特征统计协议F ₁和F ₂根据Sentinel-2卫星的光学图像获得的水域面积（基于19.97和16.53分贝（dB）之间的反向散射值）提取的水域区域的参考值介于73.4％至77.7％之间。使用特征统计协议值F ₁和F _2，基于SAR数据的模拟的HEC-RAS二维水域（2D）与参考水域之间的相似度在74.2至89.7％之间。它提供了一个明确的建议，即在没有现场观察的情况下，SAR数据可用于校准模型。通过HEC-RAS 2D模拟获得了两个基于水速和深度创建的洪水灾害图。所获得的地图表明，新开罗市的11％的道路和50％的建筑物暴露于高危险区域。此外，28％的裸地位于非常脆弱的地区。我们建议使用获得的危害图来支持应急响应并设计有效的应急计划。