Operational early warning systems for water-related hazards in Europe

Alfieri, Lorenzo; Salamon, Peter; Pappenberger, Florian; Wetterhall, F.; Thielen, Joanna

doi:10.1016/j.envsci.2012.01.008

Cited by 239 publications

(166 citation statements)

References 69 publications

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“…The thresholds corresponding to the alert levels are usually given by the depth of observed rainfall for a given duration which is likely to cause floods according to examination of rainfall accumulations during previous flooding events, and they are often refined based on the findings of post-event analyses. 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).…”

Section: Rainfall Monitoring Nowcasting and Warning Systemsmentioning

confidence: 99%

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

Panziera

Gabella

Zanini

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. This paper presents a regional extreme rainfall analysis based on 10 years of radar data for the 159 regions adopted for official natural hazard warnings in Switzerland. Moreover, a nowcasting tool aimed at issuing heavy precipitation regional alerts is introduced. The two topics are closely related, since the extreme rainfall analysis provides the thresholds used by the nowcasting system for the alerts. Warm and cold seasons' monthly maxima of several statistical quantities describing regional rainfall are fitted to a generalized extreme value distribution in order to derive the precipitation amounts corresponding to sub-annual return periods for durations of 1, 3, 6, 12, 24 and 48 h. It is shown that regional return levels exhibit a large spatial variability in Switzerland, and that their spatial distribution strongly depends on the duration of the aggregation period: for accumulations of 3 h and shorter, the largest return levels are found over the northerly alpine slopes, whereas for longer durations the southern Alps exhibit the largest values. The inner alpine chain shows the lowest values, in agreement with previous rainfall climatologies.The nowcasting system presented here is aimed to issue heavy rainfall alerts for a large variety of end users, who are interested in different precipitation characteristics and regions, such as, for example, small urban areas, remote alpine catchments or administrative districts. The alerts are issued not only if the rainfall measured in the immediate past or forecast in the near future exceeds some predefined thresholds but also as soon as the sum of past and forecast precipitation is larger than threshold values. This precipitation total, in fact, has primary importance in applications for which antecedent rainfall is as important as predicted one, such as urban floods early warning systems. The rainfall fields, the statistical quantity representing regional rainfall and the frequency of alerts issued in case of continuous threshold exceedance are some of the configurable parameters of the tool.The analysis of the urban flood which occurred in the city of Schaffhausen in May 2013 suggests that this alert tool might have complementary skill with respect to radar-based thunderstorm nowcasting systems for storms which do not show a clear convective signature.

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Section: Rainfall Monitoring Nowcasting and Warning Systemsmentioning

confidence: 99%

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

Panziera

Gabella

Zanini

et al. 2016

Hydrol. Earth Syst. Sci.

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“…Preparedness activities and flood forecasting have received increasing attention and have led to new sciencebased early action systems (Coughlan de Perez et al, 2014). Weather forecasts, with typical lead times of some hours or days, have become the basis of such systems (Alfieri et al, 2012), and they have played an important role in reducing flood impacts not only in developed countries (Rogers and Tsirkunov, 2010) but also in several lower-income ones (Golnaraghi, M. 2012;Webster, 2013). Therefore, research stresses the importance of their improvement.…”

Section: Introductionmentioning

confidence: 99%

The influence of antecedent conditions on flood risk in sub-Saharan Africa

Bischiniotis

Hurk

Jongman

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. Most flood early warning systems have predominantly focused on forecasting floods with lead times of hours or days. However, physical processes during longer timescales can also contribute to flood generation. In this study, we follow a pragmatic approach to analyse the hydrometeorological pre-conditions of 501 historical damaging floods from 1980 to 2010 in sub-Saharan Africa. These are separated into (a) weather timescale (0-6 days) and (b) seasonal timescale conditions (up to 6 months) before the event. The 7-day precipitation preceding a flood event (PRE7) and the standardized precipitation evapotranspiration index (SPEI) are analysed for the two timescale domains, respectively. Results indicate that high PRE7 does not always generate floods by itself. Seasonal SPEIs, which are not directly correlated with PRE7, exhibit positive (wet) values prior to most flood events across different averaging times, indicating a relationship with flooding. This paper provides evidence that bringing together weather and seasonal conditions can lead to improved flood risk preparedness.

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“…Some flood forecasting systems have been developed and operated in some countries (Mogil et al, 1978;Sweeney, 1992;Mason, 1982;Alfieri et al, 2012). North America has a flash flood forecasting system using GFFG.…”

Section: Utilization Of a P -A Curve For Flash Flood Forecastingmentioning

confidence: 99%

Development of a precipitation–area curve for warning criteria of short-duration flash flood

Bae

Lee

Moon

2018

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper presents quantitative criteria for flash flood warning that can be used to rapidly assess flash flood occurrence based on only rainfall estimates. This study was conducted for 200 small mountainous sub-catchments of the Han River basin in South Korea because South Korea has recently suffered many flash flood events. The quantitative criteria are calculated based on flash flood guidance (FFG), which is defined as the depth of rainfall of a given duration required to cause frequent flooding (1-2-year return period) at the outlet of a small stream basin and is estimated using threshold runoff (TR) and antecedent soil moisture conditions in all sub-basins. The soil moisture conditions were estimated during the flooding season, i.e., July, August and September, over 7 years (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) using the Sejong University Rainfall Runoff (SURR) model. A ROC (receiver operating characteristic) analysis was used to obtain optimum rainfall values and a generalized precipitation-area (P -A) curve was developed for flash flood warning thresholds. The threshold function was derived as a P -A curve because the precipitation threshold with a short duration is more closely related to basin area than any other variables. For a brief description of the P -A curve, generalized thresholds for flash flood warnings can be suggested for rainfall rates of 42, 32 and 20 mm h −1 in sub-basins with areas of 22-40, 40-100 and > 100 km 2 , respectively. The proposed P -A curve was validated based on observed flash flood events in different sub-basins. Flash flood occurrences were captured for 9 out of 12 events. This result can be used instead of FFG to identify brief flash flood (less than 1 h), and it can provide warning information to decision-makers or citizens that is relatively simple, clear and immediate.

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Operational early warning systems for water-related hazards in Europe

Cited by 239 publications

References 69 publications

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

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

The influence of antecedent conditions on flood risk in sub-Saharan Africa

Development of a precipitation–area curve for warning criteria of short-duration flash flood

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