Flash flood detection through a multi-stage probabilistic warning system for heavy precipitation events

Abstract

Abstract. The deadly combination of short to no warning lead times and the vulnerability of urbanized areas makes flash flood events extremely dangerous for the modern society. This paper contributes to flash flood early warning by proposing a multi-stage warning system for heavy precipitation events based on threshold exceedances within a probabilistic framework. It makes use of meteorological products at different resolutions, namely, numerical weather predictions (NWP), radar-NWP blending, and radar nowcasting. The system is composed by two main modules. First, a European Precipitation Index based on a simulated Climatology (EPIC) and probabilistic weather forecasts is calculated to pinpoint catchments at risk of upcoming heavy precipitation. Then, a Probabilistic Flash Flood Guidance System (PFFGS) is activated at the regional scale and uses more accurate input data to reduce the estimation uncertainty.The system is tested for a high flow event occurred in Catalonia (Spain) in November 2008 and results from the different meteorological input data are compared and discussed. The strength of coupling the two systems is shown in its ability to detect areas potentially at risk of severe meteorological conditions and then monitoring the evolution by providing more accurate information with higher spatial-temporal resolution as the event approaches.

A radar-based regional extreme rainfall analysis to derive the thresholds for a novel automatic alert system in Switzerland

“…Therefore, they tend to be specific to individual regions (e.g., Alfieri et al, 2012;Sene, 2013). Both rainfall depths L. Panziera et al: A regional extreme rainfall analysis for a novel alert system and river discharges corresponding to predefined return periods are also used as thresholds for the alerts (e.g., Alfieri et al, 2011;Knechtl, 2013;Javelle et al, 2014;Fouchier et al, 2015). For some applications, precipitation thresholds depend also on antecedent rainfall: for example, when issuing landslide, debris flow or urban flooding warnings, the amount of precipitation measured in the hours or days preceding the onset of a storm event has to be carefully considered, since it strongly influences soil saturation conditions or the spare capacity in the drainage network of a city, playing a fundamental role in determining the severity of the hazard (e.g., Neary and Swift, 1987;Giannecchini et al, 2000;Wieczorek and Glade, 2005;Martina et al, 2006;Guzzetti et al, 2007;Sene, 2013).…”

Exploring Jeddah Floods by Tropical Rainfall Measuring Mission Analysis

“…Tekeli and Fouli [35] proposed the Riyadh Flood Precipitation Index (RFPI), which is a modified version of the European Precipitation Climatology Index (EPIC) proposed by Alfieri et al [7] and by Alfieri and Thielen [38] for extreme rain storm and flash flood early warning. Modification to the EPIC implemented by [35] included the monthly calculation instead of yearly values in EPIC.…”

“…Among these 28 meteorology-based disasters, floods are the most common [4]. Despite the limited areas in which they occur [5], flash floods are the most commonly faced, the most deadly and the most challenging [6,7]. It is the limited response time that makes flash floods challenging.…”

The extreme runoff index for flood early warning in Europe

“…Many of these supported the findings that simplified approaches for flood early warning often provide as accurate results as those of physically based models, particularly when transferred to ungauged river basins. Alfieri et al (2011) proposed the European Precipitation Index based on simulated Climatology (EPIC) to monitor the European domain for upcoming severe storms possibly leading to flash floods. The main assumption of the EPIC is that statistically, extreme cumulated precipitation on smallsize catchments is a good predictor for flash floods, independent from other hydrological processes taking place in the real world.…”