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.

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>

Surface Water Management and Modelling in the Sakia El Hamra Hydraulic Basin (Southern Morocco)

2020 ◽  
Author(s):  
Nafia El-alaouy ◽  
Aicha Moumni ◽  
Badr-eddine Sebbar ◽  
Abdeljalil Gouzrou ◽  
Aberrahman Lahrouni
Keyword(s):  
Flash Flood ◽  
Hydrological Regime ◽  
Shape Index ◽  
Flash Floods ◽  
Drainage Density ◽  
Agricultural Lands ◽  
Surface Water Management ◽  
Short Period ◽  
Long Time ◽  
Log Normal

<p>Due to its arid to semi-arid climate, Morocco often faces significant intense rainfall periods that can generate flash floods and raging torrents causing serious damage in a very short period of time. In this context, these recent years, the watershed corresponding to the SAKIA EL HAMRA wadi has known devastating downpours and excessive heavy rains that caused severe floods in Laayoune city and its regions.</p><p>The watershed of Sakia El Hamra covers an area of 82000 km<sup>2</sup>, that drains to Sakia El Hamra wadi, a stream of about 447 km long, crosses the basin in its northern part in the East-to-West direction, to discharge into the Atlantic Ocean at the outlet called Foum El Oued. This zone often experiences dangerous torrents of water and violent flash floods, specifically in the northern part of Laayoune city. For example, a flash flood has occurred at the end of October 2016. The peak flow was far in excess of the average (3000 m<sup>3</sup>/s against 410m<sup>3</sup>/s). This river flood, lasted for about 10 h, caused damage to the infrastructure and destruction of agricultural lands near Foum El Oued.</p><p>The objective of this study is to investigate, through modelling, the hydrological regime of SAKIA EL HAMRA watershed to prevent the floods in the future and improve warning systems. The hydrological parameters of the watershed were determined by WMS software, namely: zone extent, perimeter, slope, basin’s average elevation, Gravelius compactness index, Horton shape index, average altitude, drainage density and concentration time.</p><p>Flood flow return was simulated using the Log-normal distribution, using a long time-series of flow and maximum daily and annual precipitation data, recorded between 1985 and 2016, at the Airport station in Laayoune city. The results showed that during flash floods with known flows, water level can reach up to 13 meters, with high flow velocities flooding hundreds of hectares of surrounding plains at the northern part of the city of Laayoune and agricultural lands near Foum El Oued.</p>

Using Climate Models to Estimate Urban Vulnerability to Flash Floods

2017 ◽  
Vol 56 (9) ◽  
pp. 2637-2650 ◽  
Author(s):  
A. Kermanshah ◽  
S. Derrible ◽  
M. Berkelhammer
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Travel Demand ◽  
Flash Flood ◽  
Flash Floods ◽  
Flood Frequency ◽  
Geographical Information ◽  
Climate System Model ◽  
Infrastructure Networks ◽  
The Impact

Abstract Climate change will impact urban infrastructure networks by changing precipitation patterns in a region. This study presents a novel vulnerability assessment framework for infrastructure networks against extreme rainfall-induced flash floods, with a specific application to transportation. The framework combines climate models, network science, geographical information systems (GIS), and stochastic modeling to compile a vulnerability surface (VS). Daily precipitation simulations for 2006–2100 from the Community Climate System Model, version 4 (CCSM4), are used to produce a stochastic simulation of extreme flash flood events in five U.S. cities—that is, Boston, Massachusetts; Houston, Texas; Miami, Florida; Oklahoma City, Oklahoma; and Philadelphia, Pennsylvania—under two different climate scenarios (RCP4.5 and RCP8.5). To assess the impact of these events, percentage drops in static (i.e., overall properties and robustness topological indicators) and dynamic (i.e., GIS accessibility and travel demand metrics) network properties are measured before and after simulated extreme events. The results of these metrics are inputs on a radar diagram to form a VS. Overall, the results show that changes in flash flood frequency due to climate change can have a significant impact on road networks, as was demonstrated recently in Houston, Texas. The magnitude of these impacts is chiefly associated with the geographic location of the cities and the size of the networks. The proposed framework can be reproduced in any city around the world, and researchers can use the results as guidelines for infrastructure design and planning purposes. Moreover, sensitivity analysis to varying greenhouse gas concentration trajectories can help local and national authorities to prioritize strategies for adaptation to climate change in more vulnerable regions.

scholarly journals A Multimethod Approach towards Assessing Urban Flood Patterns and Its Associated Vulnerabilities in Singapore

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Winston T. L. Chow ◽  
Brendan D. Cheong ◽  
Beatrice H. Ho
Keyword(s):  
Flash Flood ◽  
Flood Management ◽  
Flash Floods ◽  
Flood Frequency ◽  
Storm Events ◽  
Urban Flood ◽  
Infrastructural Development ◽  
Damage Claims ◽  
Multimethod Approach ◽  
City State

We investigated flooding patterns in the urbanised city-state of Singapore through a multimethod approach combining station precipitation data with archival newspaper and governmental records; changes in flash floods frequencies or reported impacts of floods towards Singapore society were documented. We subsequently discussed potential flooding impacts in the context of urban vulnerability, based on future urbanisation and forecasted precipitation projections for Singapore. We find that, despite effective flood management, (i) significant increases in reported flash flood frequency occurred in contemporary (post-2000) relative to preceding (1984–1999) periods, (ii) these flash floods coincide with more localised, “patchy” storm events, (iii) storms in recent years are also more intense and frequent, and (iv) floods result in low human casualties but have high economic costs via insurance damage claims. We assess that Singapore presently has low vulnerability to floods vis-à-vis other regional cities largely due to holistic flood management via consistent and successful infrastructural development, widespread flood monitoring, and effective advisory platforms. We conclude, however, that future vulnerabilities may increase from stresses arising from physical exposure to climate change and from demographic sensitivity via rapid population growth. Anticipating these changes is potentially useful in maintaining the high resilience of Singapore towards this hydrometeorological hazard.

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 Measuring Vulnerability to Flash Flood of Urban Dwellers

2021 ◽  
pp. 317-354
Author(s):  
Md. Enamul Huq ◽  
Zhenfeng Shao ◽  
Ahmed Abdullah Al Dughairi ◽  
Md. Nazirul Islam Sarker ◽  
Cai Bowen ◽  
...  
Keyword(s):  
Climatic Condition ◽  
Flash Flood ◽  
Geographic Location ◽  
Flash Floods ◽  
Primary Data ◽  
Five Factors ◽  
Short Period ◽  
Real Picture ◽  
Insight Into ◽  
Slum Population

AbstractFlash floods are unexpected, localized flood events that occur when an exceptional amount of rain falls happens over a short period of time. In South Asia, it is mostly disastrous, for example, in 2017 flash floods killed approximately 1200 people from India, Nepal, and Bangladesh. However, it is also common in Dhaka megacity, Bangladesh due to its geographic location, monsoon climatic condition and surrounding rivers. Though it is impossible to avoid them, the losses and damages of hazards can be reduced effectively by using appropriate techniques. This study aims to determine the responsible factors and measure the household vulnerability to flash flood as a tool of mitigation. The study has been conducted based on primary data. Therefore, data were collected from both slum and non-slum population to cover the entire urban habitats. Data were collected with a structured questionnaire based on five factors (social, economic, institutional, structural, and environmental) of vulnerability to flash flood. The key feature of this paper is to provide an insight into real picture of vulnerability to flash flood for urban habitants. Moreover, this practical approach is useful to quantify hazard-induced vulnerabilities not only for Dhaka megacity but also for other cities of the globe.

scholarly journals Hydrometeorological Conditions Leading to the 2015 Salgar Flash Flood: Lessons for Vulnerable Regions in Tropical Complex Terrain

2019 ◽  
Author(s):  
Carlos D. Hoyos ◽  
Lina I. Ceballos ◽  
Jhayron S. Pérez ◽  
Julián Sepúlveda ◽  
Silvana M. López ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Latin American ◽  
Complex Terrain ◽  
Flash Flood ◽  
Flash Floods ◽  
Precipitation Event ◽  
Orographic Rainfall ◽  
Short Period ◽  
Local Risk

Abstract. Flash floods are a recurrent hazard for many developing Latin American regions due to their complex mountainous terrain and the rainfall characteristics in the Tropics. These regions often lack the timely and high-quality information needed to assess, in real-time, the threats to the vulnerable communities due to extreme hydrometeorological events. The systematic assessment of past extreme events allows improving our prediction capabilities of flash floods. In May 2015, a flash flood in La Liboriana basin, municipality of Salgar, Colombia, caused more than 100 casualties and significant infrastructure damage. Despite the data scarcity, the climatological aspects, meteorological conditions, and first-order hydrometeorological mechanisms associated with La Liboriana flash flood, including orographic intensification and the spatial distribution of the rainfall intensity relative to the basin's geomorphological features, are studied using precipitation information obtained using a weather radar quantitative precipitation estimation (QPE) technique, as well as from satellite products, in situ rain gauges from neighboring basins, quantitative precipitation forecasts (QPFs) from an operational Weather Research and Forecasting (WRF) model application, and data from reanalysis products. La Liboriana flash flood took place during a period with negative precipitation anomalies over most of the country as a result of an El Niño event. However, during May 2015, moist easterly flow towards the upper part of La Liboriana caused significant orographic rainfall enhancement. The overall evidence shows an important role of successive precipitation events in a relatively short period, and of orography, in the spatial distribution of rainfall and its intensification as convective cores approached the steepest topography. There were three consecutive events generating significant rainfall within La Liboriana basin, and no single precipitation event was exceptionally large to generate the flash flood, but rather the combined role of precedent rainfall, and extreme hourly precipitation triggered the event. The results point to key lessons for improving local risk reduction strategies in vulnerable regions with complex terrain.

scholarly journals Estimation of extreme flash flood evolution in Barcelona County from 1351 to 2005

2006 ◽  
Vol 6 (4) ◽  
pp. 505-518 ◽  
Author(s):  
A. Barrera ◽  
M. C. Llasat ◽  
M. Barriendos
Keyword(s):  
Roman Empire ◽  
Flash Flood ◽  
Flood Hazard ◽  
Climatic Variability ◽  
Daily Rainfall ◽  
Weather Conditions ◽  
Flash Floods ◽  
Economic Losses ◽  
Data Series ◽  
Perception Threshold

Abstract. Every year, flash floods cause economic losses and major problems for undertaking daily activity in the Catalonia region (NE Spain). Sometimes catastrophic damage and casualties occur. When a long term analysis of floods is undertaken, a question arises regarding the changing role of the vulnerability and the hazard in risk evolution. This paper sets out to give some information to deal with this question, on the basis of analysis of all the floods that have occurred in Barcelona county (Catalonia) since the 14th century, as well as the flooded area, urban evolution, impacts and the weather conditions for any of most severe events. With this objective, the identification and classification of historical floods, and characterisation of flash-floods among these, have been undertaken. Besides this, the main meteorological factors associated with recent flash floods in this city and neighbouring regions are well-known. On the other hand, the identification of rainfall trends that could explain the historical evolution of flood hazard occurrence in this city has been analysed. Finally, identification of the influence of urban development on the vulnerability to floods has been carried out. Barcelona city has been selected thanks to its long continuous data series (daily rainfall data series, since 1854; one of the longest rainfall rate series of Europe, since 1921) and for the accurate historical archive information that is available (since the Roman Empire for the urban evolution). The evolution of flood occurrence shows the existence of oscillations in the earlier and later modern-age periods that can be attributed to climatic variability, evolution of the perception threshold and changes in vulnerability. A great increase of vulnerability can be assumed for the period 1850–1900. The analysis of the time evolution for the Barcelona rainfall series (1854–2000) shows that no trend exists, although, due to changes in urban planning, flash-floods impact has altered over this time. The number of catastrophic flash floods has diminished, although the extraordinary ones have increased.

Numerical investigation of sediment-charged flash flood due to a cascade of natural dam failures

2020 ◽  
Author(s):  
Mingfu Guan
Keyword(s):  
Flash Flood ◽  
Landslide Dam ◽  
Flash Floods ◽  
Steep Slope ◽  
River Valley ◽  
Dam Failure ◽  
Dam Failures ◽  
Short Period ◽  
Natural Dam ◽  
High Sediment

<p>Landslide natural dams are commonly formed in a river valley of mountainous areas due to heavy rainfall or earthquake, which can be a complete or partial blockage. Different from conventional man-made dams, natural dams typically comprise unconsolidated and poorly sorted material, and are vulnerable to failure and breaching in short period due to overtopping or seepage. For those small sediment blockage in a river valley, their failures frequently occur during high intense rainfalls, which will induce a large flash flood with high-concentrated sediment downstream in a short period, and the magnitude is likely to be amplified along the flow direction due to the inclusion of a large amount of sediment. This can result in significant and sudden debris flow or high sediment-charged flash flood in the downstream for human life and property. Cascade failures of a series of natural dams in a gully have been considered to be a primary reason for the enlargement of high sediment-laden flash flood. In general, cascading natural dams can be formed along the sloping channel due to the randomness and unpredictability of landslides, which complexes the hydraulics of landslide dam failures.</p><p>This study evaluates the formation and development of sediment-charged flash floods due to cascading failure of natural dams through detailed hydro-morphodynamic modelling. The model used is based on shallow water theory and it has been successful in predicting the flow and morphological process during sudden dam-break, as well as full and partial dyke-breach.  The study first calibrates the model with experiemntal data of a cascade of partical blockage dam failures. Then the calibrated model is applied to two types of natural dam failure cases: (1) straight steep slope channel with a series of small partial blockage dams; (2) bend channel with steep slope including a series of partical blockage dams. For both cases, various scenarios are modelled, including: (1) failure of a single dam in a sloping channel, (2) failure of two dams in a sloping channel, (3) failure of multiple landslide dams (four) in a sloping channel. Based on the detailed model results, the study systematically explores the tempo-spatial evolution of sediment-charged flash floods (discharge, flow velocity, and flow concentration) and geomorphic properties along the steep sloping channel.  The effects of in-channel erosion and flow-driven sediment from dams on the evolution of flood dynamic process are analysed.  The results improve the understanding of the formation and development mechanism of flash floods due to cascading landslide dam failures.  The findings are beneficial for downstream flood risk assessment and developing control strategies for landslide-induced floods.</p>

scholarly journals Flash Flood Events along the West Mediterranean Coasts: Inundations of Urbanized Areas Conditioned by Anthropic Impacts

Land ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 620
Author(s):  
Francesco Faccini ◽  
Fabio Luino ◽  
Guido Paliaga ◽  
Anna Roccati ◽  
Laura Turconi
Keyword(s):  
Flash Flood ◽  
Urban Expansion ◽  
Mediterranean Area ◽  
Flash Floods ◽  
Flood Frequency ◽  
Flood Events ◽  
Intense Rainfall ◽  
Frequency Increase ◽  
Ligurian Sea ◽  
Ground Effects

Flash floods represent one of the natural hazards that causes the greatest number of victims in the Mediterranean area. These processes occur by short and intense rainfall affecting limited areas of a few square kilometers, with rapid hydrological responses. Among the causes of the flood frequency increase in the last decades are the effects of the urban expansion in areas of fluvial pertinence and climatic change, namely the interaction between anthropogenic landforms and hydro-geomorphological dynamics. In this paper the authors show a comparison between flood events with very similar weather-hydrological characteristics and the ground effects occurred in coastal areas of three regions located at the top of a triangle in the Ligurian Sea, namely Liguria, Tuscany and Sardinia. With respect to the meteorological-hydrological hazard, it should be noted that the events analyzed occurred during autumn, in the conditions of a storm system triggered by cyclogenesis on the Genoa Gulf or by the extra-tropical cyclone Cleopatra. The “flash floods” damage recorded in the inhabited areas is due to the vulnerability of the elements at risk in the fluvio-coastal plains examined. There are numerous anthropogenic forcings that have influenced the hydro-geomorphological dynamics and that have led to an increase in risk conditions.

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