scholarly journals Limiares de chuva deflagradores de inundações bruscas: metodologia, aplicação e avaliação em ambiente operacional

Revista DAE ◽  
2019 ◽  
Vol 221 (68) ◽  
pp. 71-86
Author(s):  
Luiz Carlos Salgueiro Donato Bacelar ◽  
Aliana Maciel ◽  
Carlos Frederico de Angelis ◽  
Javier Tomasella
Keyword(s):  
Flash Flood ◽  
Flash Floods ◽  
Atmospheric Modeling ◽  
Rainfall Data ◽  
Rainfall Thresholds ◽  
Rain Gauges ◽  
Weather Radars ◽  
Diagnosis And Prognosis ◽  
Historical Series ◽  
Technical Article

The present technical article refers to the methodology, application and evaluation of the first computational tool for diagnosis and prognosis of flash floods, based on rain thresholds, which was implemented in the platform of the National Center for Monitoring and Early Warning of Natural Disasters (Cemaden). From historical series of river levels and rainfall data, a procedure was developed to construct relationships that indicate the amount of rain necessary to increase the probability of flash floods occurring in up to twentyfour hours. Rainfall data from rain gauges, weather radars, satellites and atmospheric modeling are used for real-time monitoring of the pre-es- tablished critical rainfall thresholds, integrated into the monitoring and operation. Three cases of flash flood risk warnings sent after the implementation of the tool were analyzed, which demonstrated a good performance in the anticipation of flash floods hazard situations. O presente artigo refere-se à apresentação da metodologia, aplicação e avaliação da primeira ferramenta computacional para diagnóstico e prognóstico para inundações bruscas, baseada em limiares de chuva, que foi implementada na plataforma do Centro Nacional de Monitoramento e Alerta de Desastres Naturais (Cemaden). A partir de séries históricas de níveis dos rios e dados pluviométricos, um procedimento foi ela- borado para construir relações que indicam a quantidade de chuva necessária para aumento da probabilidade de ocorrência de inundações bruscas em até vinte e quatro horas. Os dados de precipitação provenientes de pluviômetros, radares meteorológicos, satélites e modelagem atmosférica por conjunto são utilizados para acompanhamento em tempo real dos níveis críticos de chuva pré-estabelecidos, integrados ao monitoramen- to e operação. Foram analisados três casos de alertas de risco às inundações bruscas, enviados após a implementação da ferramenta, que demonstrou um bom desempenho na antecipação de situações de perigo devido às inundações bruscas

scholarly journals Assessing long term flash flooding frequency using historical information

2016 ◽  
Vol 48 (1) ◽  
pp. 1-16 ◽  
Author(s):  
David R. Archer ◽  
Geoff Parkin ◽  
Hayley J. Fowler
Keyword(s):  
Time Series ◽  
Flash Flood ◽  
Climatic Variability ◽  
Flash Floods ◽  
Abrupt Onset ◽  
Flood Frequency ◽  
Historical Information ◽  
Short Period ◽  
Historical Series ◽  
Historical Accounts

Flash floods are distinguished from ‘normal flooding’ by an abrupt onset arising from intense short period rainfall. Historical information based on pre-gauged descriptive information is used to prepare time series of flash floods for Northeast England and Southwest England as decadal numbers of events from 1800. The time series show a minimum in the late twentieth century for both locations. Flash flood frequency is then assessed for three locations in Northeast England by comparing recent extreme floods with historical accounts: (1) an urban pluvial flood in Newcastle in June 2012, (2) a severe flood in September 1968 on the Cotting Burn, a small ungauged tributary of the River Wansbeck, and (3) an extreme rate of rise in river level on the River Wansbeck in August 1994. Although there have been no comparable recent occurrences, several flash floods of equal or greater magnitude at the same locations were identified from historical accounts. Using the longer historical record in conjunction with limited recent observations has advantages when assessing the frequency of occurrence of rare events. However, these advantages are tempered by the possibility of non-stationarity in the historical series owing to catchment changes, from natural climatic variability and from potential anthropogenic climate change.

scholarly journals Rainstorms able to induce flash floods in a Mediterranean-climate region (Calabria, southern Italy)

2014 ◽  
Vol 14 (9) ◽  
pp. 2423-2434 ◽  
Author(s):  
O. G. Terranova ◽  
S. L. Gariano
Keyword(s):  
Mediterranean Climate ◽  
Southern Italy ◽  
Flash Flood ◽  
Temporal Structure ◽  
Flash Floods ◽  
Rain Gauges ◽  
Mediterranean Countries ◽  
Preliminary Validation ◽  
The Mediterranean ◽  
Landslides And Debris Flows

Abstract. Heavy rainstorms often induce flash flooding, one of the natural disasters most responsible for damage to man-made infrastructures and loss of lives, also adversely affecting the opportunities for socio-economic development of Mediterranean countries. The frequently dramatic damage of flash floods are often detected, with sufficient accuracy, by post-event surveys, but rainfall causing them are still only roughly characterized. With the aim of improving the understanding of the temporal structure and spatial distribution of heavy rainstorms in the Mediterranean context, a statistical analysis was carried out in Calabria (southern Italy) concerning rainstorms that mainly induced flash floods, but also shallow landslides and debris flows. Thus, a method is proposed – based on the overcoming of heuristically predetermined threshold values of cumulated rainfall, maximum intensity, and kinetic energy of the rainfall event – to select and characterize the rainstorms able to induce flash floods in the Mediterranean-climate countries. Therefore, the obtained (heavy) rainstorms were automatically classified and studied according to their structure in time, localization, and extension. Rainfall-runoff watershed models can consequently benefit from the enhanced identification of design storms, with a realistic time structure integrated with the results of the spatial analysis. A survey of flash flood events recorded in the last decades provides a preliminary validation of the method proposed to identify the heavy rainstorms and synthetically describe their characteristics. The notable size of the employed sample, including data with a very detailed resolution in time that relate to several rain gauges well-distributed throughout the region, gives robustness to the obtained results.

scholarly journals Bias Correction of Satellite-Based Rainfall Estimates for Modeling Flash Floods in Semi-Arid regions: Application to Karpuz River, Turkey

2016 ◽  
Author(s):  
Mohamed Saber ◽  
Koray Yilmaz
Keyword(s):  
Bias Correction ◽  
Flash Flood ◽  
Flash Floods ◽  
Rainfall Rate ◽  
Assessment Model ◽  
Model Parameters ◽  
Flood Events ◽  
Rain Gauges ◽  
Semi Arid ◽  
Rainfall Estimates

Abstract. This study investigates the utility of gauge-corrected satellite-based rainfall estimates in simulating flash floods at Karpuz River - a semi-arid basin in Turkey. Global Satellite Mapping of Precipitation (GSMaP) product was evaluated with the rain gauge network at monthly and daily time-scales considering various time periods and rainfall rate thresholds. Statistical analysis indicated that GSMaP shows acceptable linear correlation coefficient with rain gauges however suffers from significant underestimation bias. A rainfall rate threshold of 1 mm/month was the best choice to improve the match between GSMaP and rain gauges implying that appropriate threshold selection is critically important for the bias correction. Multiplicative bias correction was applied to GSMaP data using the bias factors calculated between GSMaP and observed rainfall. Hydrological River Basin Environmental Assessment Model (Hydro-BEAM) was used to simulate flash floods at the hourly time scale driven by the corrected GSMaP rainfall data. The model parameters were calibrated for flash flood events during October-December 2007 and then validated for flash flood events during October-December 2009. The results show that the simulated surface runoff hydrographs reasonably coincide with the observed hydrographs.

scholarly journals Technical Note: An operational landslide early warning system at regional scale based on space–time-variable rainfall thresholds

2015 ◽  
Vol 15 (4) ◽  
pp. 853-861 ◽  
Author(s):  
S. Segoni ◽  
A. Battistini ◽  
G. Rossi ◽  
A. Rosi ◽  
D. Lagomarsino ◽  
...  
Keyword(s):  
Real Time ◽  
Early Warning ◽  
Early Warning System ◽  
Warning System ◽  
Rainfall Event ◽  
Rainfall Data ◽  
Limited Area ◽  
Rainfall Thresholds ◽  
Rain Gauges ◽  
Starting Time

Abstract. We set up an early warning system for rainfall-induced landslides in Tuscany (23 000 km2). The system is based on a set of state-of-the-art intensity–duration rainfall thresholds (Segoni et al., 2014b) and makes use of LAMI (Limited Area Model Italy) rainfall forecasts and real-time rainfall data provided by an automated network of more than 300 rain gauges. The system was implemented in a WebGIS to ease the operational use in civil protection procedures: it is simple and intuitive to consult, and it provides different outputs. When switching among different views, the system is able to focus both on monitoring of real-time data and on forecasting at different lead times up to 48 h. Moreover, the system can switch between a basic data view where a synoptic scenario of the hazard can be shown all over the region and a more in-depth view were the rainfall path of rain gauges can be displayed and constantly compared with rainfall thresholds. To better account for the variability of the geomorphological and meteorological settings encountered in Tuscany, the region is subdivided into 25 alert zones, each provided with a specific threshold. The warning system reflects this subdivision: using a network of more than 300 rain gauges, it allows for the monitoring of each alert zone separately so that warnings can be issued independently. An important feature of the warning system is that the visualization of the thresholds in the WebGIS interface may vary in time depending on when the starting time of the rainfall event is set. The starting time of the rainfall event is considered as a variable by the early warning system: whenever new rainfall data are available, a recursive algorithm identifies the starting time for which the rainfall path is closest to or overcomes the threshold. This is considered the most hazardous condition, and it is displayed by the WebGIS interface. The early warning system is used to forecast and monitor the landslide hazard in the whole region, providing specific alert levels for 25 distinct alert zones. In addition, the system can be used to gather, analyze, display, explore, interpret and store rainfall data, thus representing a potential support to both decision makers and scientists.

scholarly journals Rainstorms able to induce flash floods in a Mediterranean-climate region (Calabria, southern Italy)

2014 ◽  
Vol 2 (3) ◽  
pp. 2049-2078 ◽  
Author(s):  
O. G. Terranova ◽  
S. L. Gariano
Keyword(s):  
Mediterranean Climate ◽  
Southern Italy ◽  
Flash Flood ◽  
Temporal Structure ◽  
Flash Floods ◽  
Rain Gauges ◽  
Mediterranean Countries ◽  
Preliminary Validation ◽  
The Mediterranean ◽  
Landslides And Debris Flows

Abstract. Heavy rainstorms often induce flash flooding, one of the natural disasters most responsible for damage to man-made infrastructure and loss of lives, adversely affecting also the opportunities for socio-economic development of Mediterranean Countries. The frequently dramatic damage of flash floods are often detected with sufficient accuracy by post-event surveys, but rainfall causing them are still only roughly characterized. With the aim of improving the understanding of the temporal structure and spatial distribution of heavy rainstorms in the Mediterranean context, a statistical analysis was carried out in Calabria (southern Italy) concerning rainstorms that mainly induced flash floods, but also shallow landslides and debris-flows. Thus a method is proposed – based on the overcoming of heuristically predetermined threshold values of cumulated rainfall, maximum intensity, and kinetic energy of the rainfall event – to select and characterize the rainstorms able to induce flash floods in the Mediterranean-climate Countries. Therefore the obtained (heavy) rainstorms were automatically classified and studied according to their structure in time, localization and extension. Rainfall-runoff watershed models can consequently benefit from the enhanced identification of design storms, with a realistic time structure integrated with the results of the spatial analysis. A survey of flash flood events recorded in the last decades provides a preliminary validation of the method proposed to identify the heavy rainstorms and synthetically describe their characteristics. The notable size of the employed sample, including data with a very detailed resolution in time, that relate to several rain gauges well-distributed throughout the region, give robustness to the obtained results.

scholarly journals Technical Note: An operational landslide early warning system at regional scale based on space–time variable rainfall thresholds

2014 ◽  
Vol 2 (10) ◽  
pp. 6599-6622 ◽  
Author(s):  
S. Segoni ◽  
A. Battistini ◽  
G. Rossi ◽  
A. Rosi ◽  
D. Lagomarsino ◽  
...  
Keyword(s):  
Real Time ◽  
Early Warning ◽  
Early Warning System ◽  
Recursive Algorithm ◽  
Regional Scale ◽  
Warning System ◽  
Rainfall Data ◽  
Critical Threshold ◽  
Rainfall Thresholds ◽  
Rain Gauges

Abstract. We set up an early warning system for rainfall-induced landslides in Tuscany (23 000 km2). The system is based on a set of state-of-the-art intensity-duration rainfall thresholds (Segoni et al., 2014b), makes use of LAMI rainfall forecasts and real-time rainfall data provided by an automated network of more than 300 rain-gauges. The system was implemented in a WebGIS to ease the operational use in civil protection procedures: it is simple and intuitive to consult and it provides different outputs. Switching among different views, the system is able to focus both on monitoring of real time data and on forecasting at different lead times up to 48 h. Moreover, the system can switch between a very straightforward view where a synoptic scenario of the hazard can be shown all over the region and a more in-depth view were the rainfall path of rain-gauges can be displayed and constantly compared with rainfall thresholds. To better account for the high spatial variability of the physical features, which affects the relationship between rainfall and landslides, the region is subdivided into 25 alert zones, each provided with a specific threshold. The warning system reflects this subdivision: using a network of 332 rain gauges, it allows monitoring each alert zone separately and warnings can be issued independently from an alert zone to another. An important feature of the warning system is the use of thresholds that may vary in time adapting at the conditions of the rainfall path recorded by the rain-gauges. Depending on when the starting time of the rainfall event is set, the comparison with the threshold may produce different outcomes. Therefore, a recursive algorithm was developed to check and compare with the thresholds all possible starting times, highlighting the worst scenario and showing in the WebGIS interface at what time and how much the rainfall path has exceeded or will exceed the most critical threshold. Besides forecasting and monitoring the hazard scenario over the whole region with hazard levels differentiated for 25 distinct alert zones, the system can be used to gather, analyze, visualize, explore, interpret and store rainfall data, thus representing a potential support to both decision makers and scientists.

scholarly journals A Survey of Remote Sensing and Geographic Information System Applications for Flash Floods

2021 ◽  
Vol 13 (9) ◽  
pp. 1818
Author(s):  
Lisha Ding ◽  
Lei Ma ◽  
Longguo Li ◽  
Chao Liu ◽  
Naiwen Li ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Information System ◽  
Geographic Information System ◽  
Flash Flood ◽  
Flash Floods ◽  
Geographic Information ◽  
Flood Disaster ◽  
Future Research ◽  
Time Zone ◽  
Gis Technologies

Flash floods are among the most dangerous natural disasters. As climate change and urbanization advance, an increasing number of people are at risk of flash floods. The application of remote sensing and geographic information system (GIS) technologies in the study of flash floods has increased significantly over the last 20 years. In this paper, more than 200 articles published in the last 20 years are summarized and analyzed. First, a visualization analysis of the literature is performed, including a keyword co-occurrence analysis, time zone chart analysis, keyword burst analysis, and literature co-citation analysis. Then, the application of remote sensing and GIS technologies to flash flood disasters is analyzed in terms of aspects such as flash flood forecasting, flash flood disaster impact assessments, flash flood susceptibility analyses, flash flood risk assessments, and the identification of flash flood disaster risk areas. Finally, the current research status is summarized, and the orientation of future research is also discussed.

Point process models of rainfall: developments for fine-scale structure

2007 ◽  
Vol 463 (2086) ◽  
pp. 2569-2587 ◽  
Author(s):  
Paul Cowpertwait ◽  
Valerie Isham ◽  
Christian Onof
Keyword(s):  
Poisson Process ◽  
Time Scales ◽  
Rain Gauge ◽  
Historical Record ◽  
Rainfall Data ◽  
Process Models ◽  
Third Order ◽  
Time Intervals ◽  
Historical Series ◽  
Derived Properties

A conceptual stochastic model of rainfall is proposed in which storm origins occur in a Poisson process, where each storm has a random lifetime during which rain cell origins occur in a secondary Poisson process. In addition, each cell has a random lifetime during which instantaneous random depths (or ‘pulses’) of rain occur in a further Poisson process. A key motivation behind the model formulation is to account for the variability in rainfall data over small (e.g. 5 min) and larger time intervals. Time-series properties are derived to enable the model to be fitted to aggregated rain gauge data. These properties include moments up to third order, the probability that an interval is dry, and the autocovariance function. To allow for distinct storm types (e.g. convective and stratiform), several processes may be superposed. Using the derived properties, a model consisting of two storm types is fitted to 60 years of 5 min rainfall data taken from a site near Wellington, New Zealand, using sample estimates taken at 5 min, 1 hour, 6 hours and daily levels of aggregation. The model is found to fit moments of the depth distribution up to third order very well at these time scales. Using the fitted model, 5 min series are simulated, and annual maxima are extracted and compared with equivalent values taken from the historical record. A good fit in the extremes is found at both 1 and 24 hour levels of aggregation, although at the 5 min level there is some underestimation of the historical values. Proportions of time intervals with depths below various low thresholds are extracted from the simulated and historical series and compared. A tendency for underestimation of the historical values is evident at some time scales, with a close fit being obtained as the threshold is increased.

Using convection-permitting climate models and a high-resolution distributed hydrological model to assess future changes in Alpine flash floods.

2021 ◽  
Author(s):  
Marjanne Zander ◽  
Pety Viguurs ◽  
Frederiek Sperna Weiland ◽  
Albrecht Weerts
Keyword(s):  
High Resolution ◽  
Natural Hazards ◽  
Climate Models ◽  
Flash Flood ◽  
Regional Climate ◽  
Flash Floods ◽  
Flood Frequency ◽  
Climate Dynamics ◽  
Future Climate ◽  
European Climate

<p>Flash Floods are damaging natural hazards which often occur in the European Alps. Precipitation patterns and intensity may change in a future climate affecting their occurrence and magnitude. For impact studies, flash floods can be difficult to simulate due the complex orography and limited extent & duration of the heavy rainfall events which trigger them. The new generation convection-permitting regional climate models improve the intensity and frequency of heavy precipitation (Ban et al., 2021).</p><p>Therefore, this study combines such simulations with high-resolution distributed hydrological modelling to assess changes in flash flood frequency and occurrence over the Alpine terrain. We use the state-of-the-art Unified Model (Berthou et al., 2018) to drive a high-resolution distributed hydrological wflow_sbm model (e.g. Imhoff et al., 2020) covering most of the Alpine mountain range on an hourly resolution. Simulations of the future climate RCP 8.5 for the end-of-century (2096-2105) and current climate (1998-2007) are compared.</p><p>First, the wflow_sbm model was validated by comparing ERA5 driven simulation with streamflow observations (across Rhone, Rhine, Po, Adige and Danube). Second, the wflow_sbm simulation driven by UM simulation of the current climate was compared to a dataset of historical flood occurrences (Paprotny et al., 2018, Earth Syst. Sci. Data) to validate if the model can accurately simulate the location of the flash floods and to determine a suitable threshold for flash flooding. Finally, the future run was used to asses changes in flash flood frequency and occurrence. Results show an increase in flash flood frequency for the Upper Rhine and Adige catchments. For the Rhone the increase was less pronounced. The locations where the flash floods occur did not change much.</p><p>This research is embedded in the EU H2020 project EUCP (EUropean Climate Prediction system) (https://www.eucp-project.eu/), which aims to support climate adaptation and mitigation decisions for the coming decades by developing a regional climate prediction and projection system based on high-resolution climate models for Europe.</p><p> </p><p>N. Ban, E. Brisson, C. Caillaud, E. Coppola, E. Pichelli, S. Sobolowski, …, M.J. Zander (2021): “The first multi-model ensemble of regional climate simulations at the kilometer-scale resolution, Part I: Evaluation of precipitation”, manuscript accepted for publication in Climate Dynamics.</p><p>S. Berthou, E.J. Kendon, S. C. Chan, N. Ban, D. Leutwyler, C. Schär, and G. Fosser, 2018, “Pan-european climate at convection-permitting scale: a model intercomparison study.” Climate Dynamics, pages 1–25, DOI: 10.1007/s00382-018-4114-6</p><p>Imhoff, R.O., W. van Verseveld, B. van Osnabrugge, A.H. Weerts, 2020. “Scaling point-scale pedotransfer functions parameter estimates for seamless large-domain high-resolution distributed hydrological modelling: An example for the Rhine river.” Water Resources Research, 56. Doi: 10.1029/2019WR026807</p><p>Paprotny, D., Morales Napoles, O., & Jonkman, S. N., 2018. "HANZE: a pan-European database of exposure to natural hazards and damaging historical floods since 1870". Earth System Science Data, 10, 565–581, https://doi.org/10.5194/essd-10-565-2018</p>

scholarly journals Assessment of flash floods taking into account climate change scenarios in the Llobregat River basin

2013 ◽  
Vol 13 (12) ◽  
pp. 3145-3156 ◽  
Author(s):  
M. Velasco ◽  
P. A. Versini ◽  
A. Cabello ◽  
A. Barrera-Escoda
Keyword(s):  
River Basin ◽  
Extreme Events ◽  
Hydrological Model ◽  
Flash Flood ◽  
Flash Floods ◽  
Climate Change Scenarios ◽  
Whole Process ◽  
The Future ◽  
Peak Over Threshold ◽  
Llobregat River

Abstract. Global change may imply important changes in the future occurrence and intensity of extreme events. Climate scenarios characterizing these plausible changes were previously obtained for the Llobregat River basin (NE Spain). This paper presents the implementation of these scenarios in the HBV (Hydrologiska Byråns Vattenbalansavdelning) hydrological model. Then, the expected changes in terms of flash flood occurrence and intensity are assessed for two different sub-basins: the Alt Llobregat and the Anoia (Llobregat River basin). The assessment of future flash floods has been done in terms of the intensity and occurrence of extreme events, using a peak over threshold (POT) analysis. For these two sub-basins, most of the simulated scenarios present an increase of the intensity of the peak discharge values. On the other hand, the future occurrence follows different trends in the two sub-basins: an increase is observed in Alt Llobregat but a decrease occurs in Anoia. Despite the uncertainties that appear in the whole process, the results obtained can shed some light on how future flash floods events may occur.

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