Pluvial flash floods are among the most dangerous weather-triggered disasters, usually affecting watersheds smaller than 100 km², with a short time to peak discharge (from a few minutes to a few hours) after causative rainfall. Several warning systems in the world try to use this time lag to predict the location, extent, intensity, and time of flash flooding. They are based on numerical hydrological models processing data collected by on-ground monitoring networks, weather radars, and precipitation nowcasting. However, there may be areas covered by weather radar data, in which the network of ground-based precipitation stations is not sufficiently developed or does not even exist (e.g., in an area covered by portable weather radar). We developed a method usable for designing an early warning system based on a different philosophy for such a situation. This method uses weather radar data as a 2D signal carrying information on the current precipitation distribution over the monitored area, and data on the watershed and drainage network in the area. The method transforms (concentrates) the 2D signal on precipitation distribution into a 1D signal carrying information on potential runoff distribution along the drainage network. For sections of watercourses where a significant increase in potential runoff can be expected (i.e., a significant increase of the 1D signal strength is detected), a warning against imminent flash floods can be possibly issued. The whole curve of the potential runoff development is not essential for issuing the alarm, but only the significant leading edge of the 1D signal is important. The advantage of this procedure is that results are obtained quickly and independent of any on-ground monitoring system; the disadvantage is that it does not provide the exact time of the onset of a flash flooding or its extent and intensity. The generated alert only warns that there is a higher flash flooding hazard in a specific section of the watercourse in the coming hours. The forecast is presented as a dynamic map of the flash flooding hazard distribution along the segments of watercourses. Relaying this hazard to segments of watercourses permits a substantial reduction in false alarms issued to not-endangered municipalities, which lie in safe areas far away from the watercourses. The method was tested at the local level (pluvial flash floods in two small regions of the Czech Republic) and the national level for rainfall episodes covering large areas in the Czech Republic. The conclusion was that the method is applicable at both levels. The results were compared mainly with data related to the Fire and Rescue Service interventions during floods. Finally, the increase in the reliability of hazard prediction using the information on soil saturation is demonstrated. The method is applicable in any region covered by a weather radar (e.g., a portable one), even if there are undeveloped networks of rain and hydrometric gauge stations. Further improvement could be achieved by processing more extended time series and using computational intelligence methods for classifying the degree of flash flooding hazard on individual sections of the watercourse network.

中文翻译：

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使用天气雷达数据进行动态雨洪洪水灾害预报

暴雨洪水是最危险的天气引发的灾害之一，通常影响小于 100 公里的流域², 在引起降雨后达到峰值排放的时间很短（从几分钟到几小时）。世界上有几个预警系统试图利用这个时间滞后来预测山洪暴发的位置、范围、强度和时间。它们基于处理由地面监测网络、天气雷达和降水临近预报收集的数据的数值水文模型。然而，可能存在天气雷达数据覆盖的区域，在这些区域中，地面降水站网络不够发达，甚至根本不存在（例如，在便携式天气雷达覆盖的区域）。针对这种情况，我们开发了一种可用于设计基于不同理念的预警系统的方法。该方法使用天气雷达数据作为二维信号，携带有关监测区域当前降水分布的信息，以及该区域流域和排水管网的数据。该方法将降水分布的二维信号转换（集中）为一维信号，该信号承载沿排水管网的潜在径流分布信息。对于预计潜在径流显着增加（即检测到一维信号强度显着增加）的水道部分，可能会发布针对即将发生的山洪暴发的警告。潜在径流发展的整个曲线对于发出警报并不重要，但只有一维信号的显着前沿才是重要的。该程序的优点是可以快速获得结果并且独立于任何地面监测系统；缺点是它没有提供山洪暴发的确切时间或其范围和强度。生成的警报仅警告在未来几小时内水道的特定部分存在更高的山洪暴发危险。预测显示为沿河段的山洪灾害分布动态图。将这种危害传递到水道段，可以大大减少向远离水道的安全区域的非濒危城市发出的误报。该方法在地方层面（捷克共和国两个小地区的暴雨）和国家层面对覆盖捷克共和国大片地区的降雨事件进行了测试。结论是该方法适用于两个级别。结果主要与洪水期间消防和救援服务干预相关的数据进行了比较。最后，证明了使用土壤饱和度信息提高灾害预测的可靠性。该方法适用于天气雷达（例如，便携式雷达）覆盖的任何区域，即使存在未开发的雨量和水文测量站网络。