Measuring Vulnerability to Flash Flood of Urban Dwellers

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.

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

10.5194/egusphere-egu2020-8635 ◽

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

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.The watershed of Sakia El Hamra covers an area of 82000 km2, 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 m3/s against 410m3/s). This river flood, lasted for about 10 h, caused damage to the infrastructure and destruction of agricultural lands near Foum El Oued.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&#8217;s average elevation, Gravelius compactness index, Horton shape index, average altitude, drainage density and concentration time.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.

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Assessing long term flash flooding frequency using historical information

Hydrology Research ◽

10.2166/nh.2016.031 ◽

2016 ◽

Vol 48 (1) ◽

pp. 1-16 ◽

Cited By ~ 9

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.

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

10.5194/nhess-2019-171 ◽

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.

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

10.5194/egusphere-egu2020-6604 ◽

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

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.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.&#160; 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.&#160; The effects of in-channel erosion and flow-driven sediment from dams on the evolution of flood dynamic process are analysed. &#160;The results improve the understanding of the formation and development mechanism of flash floods due to cascading landslide dam failures.&#160; The findings are beneficial for downstream flood risk assessment and developing control strategies for landslide-induced floods.

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Meteorological conditions leading to the 2015 Salgar flash flood: lessons for vulnerable regions in tropical complex terrain

Natural Hazards and Earth System Science ◽

10.5194/nhess-19-2635-2019 ◽

2019 ◽

Vol 19 (11) ◽

pp. 2635-2665 ◽

Cited By ~ 3

Author(s):

Carlos D. Hoyos ◽

Lina I. Ceballos ◽

Jhayron S. Pérez-Carrasquilla ◽

Julián Sepúlveda ◽

Silvana M. López-Zapata ◽

...

Keyword(s):

Spatial Distribution ◽

Latin American ◽

Complex Terrain ◽

Flash Flood ◽

Flash Floods ◽

Meteorological Conditions ◽

Precipitation Event ◽

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 us to improve our prediction capabilities of flash floods. In May 2015, a flash flood in the 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 the 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 Model (WRF) application, and data from reanalysis products. The 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 the La Liboriana basin, and no single precipitation event was exceptionally large enough to generate the flash flood, but rather the combined role of precedent rainfall and the extreme hourly precipitation triggered the event. The results point to key lessons for improving local risk reduction strategies in vulnerable regions with complex terrain.

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

Remote Sensing ◽

10.3390/rs13091818 ◽

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.

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

10.5194/egusphere-egu21-11484 ◽

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

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).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.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.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.&#160;N. Ban, E. Brisson, C. Caillaud, E. Coppola, E. Pichelli, S. Sobolowski, &#8230;, M.J. Zander (2021): &#8220;The first multi-model ensemble of regional climate simulations at the kilometer-scale resolution, Part I: Evaluation of precipitation&#8221;, manuscript accepted for publication in Climate Dynamics.S. Berthou, E.J. Kendon, S. C. Chan, N. Ban, D. Leutwyler, C. Sch&#228;r, and G. Fosser, 2018, &#8220;Pan-european climate at convection-permitting scale: a model intercomparison study.&#8221; Climate Dynamics, pages 1&#8211;25, DOI: 10.1007/s00382-018-4114-6Imhoff, R.O., W. van Verseveld, B. van Osnabrugge, A.H. Weerts, 2020. &#8220;Scaling point-scale pedotransfer functions parameter estimates for seamless large-domain high-resolution distributed hydrological modelling: An example for the Rhine river.&#8221; Water Resources Research, 56. Doi: 10.1029/2019WR026807Paprotny, 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&#8211;581, https://doi.org/10.5194/essd-10-565-2018

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

Natural Hazards and Earth System Science ◽

10.5194/nhess-13-3145-2013 ◽

2013 ◽

Vol 13 (12) ◽

pp. 3145-3156 ◽

Cited By ~ 9

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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SOCIAL CONSCIOUSNESS IN THREE SHORT STORIES WRITTEN BY LEO TOLSTOY

International Journal of Humanities, Philosophy and Language ◽

10.35631/ijhpl.280018 ◽

2019 ◽

Vol 2 (8) ◽

pp. 241-248

Author(s):

Faiha Fakhari Mousa Alkayed

Keyword(s):

Short Stories ◽

Human Life ◽

Social Consciousness ◽

Leo Tolstoy ◽

Deep Insight ◽

The Social ◽

Real Picture ◽

Insight Into

The paper presents a discussion of three selected short stories written by Leo Tolstoy namely: “God Sees the Truth but Wait, Three Questions, and What Men Live By”. Thus, the aim of this paper is to reveal the social consciousness as appeared in such literary kind because awareness plays an important role in people's lives and all our lives are built on the awareness of things. However, it has been noticed that this work of Leo Tolstoy mirrors awareness of traditional and modern values and have thematic varieties, deep insight into human realities and characters. The stories of Leo Tolstoy represent an authentic and real picture of human life which considered being a convincing story.

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Designating Appropriate Areas for Determining Potential Rainwater Harvesting in Arid Region Using a GIS-based Multi-criteria Decision Analysis ‏

10.21203/rs.3.rs-901829/v1 ◽

2021 ◽

Author(s):

Mohamed Abd-el-Kader ◽

Ahmed Elfeky ◽

Mohamed Saber ◽

Maged AlHarbi ◽

abed Alataway

Keyword(s):

Water Management ◽

Saudi Arabia ◽

Decision Analysis ◽

Rainwater Harvesting ◽

Flash Flood ◽

Flood Hazard ◽

Flash Floods ◽

Flood Mitigation ◽

Water Harvesting ◽

Multi Criteria Decision Analysis

Abstract Flash floods are highly devastating, however there is no effective management for their water in Saudi Arabia, therefore, it is crucial to adopt Rainfall Water Harvesting (RWH) techniques to mitigate the flash floods and manage the available water resources from the infrequent and rare rainfall storms. The goal of this study is to create a potential flood hazard map and a map of suitable locations for RWH in Wadi Nisah, Saudi Arabia for future water management and flood prevention plans and to identify potential areas for rainwater harvesting and dam construction for both a flood mitigation and water harvesting. This research was carried out using a spatiotemporal distributed model based on multi-criteria decision analysis by combining Geographic Information System (GIS), Remote Sensing (RS), and Multi-Criteria Decision-Making tools (MCDM). The flood hazard mapping criteria were elevation, drainage density, slope, direct runoff depth at 50 years return period, Topographic witness index, and Curve Number, according to the Multi-criteria decision analysis, while the criteria for RWH were Slope, Land cover, Stream order, Lineaments density, and Average of annual max-24hr Rainfall. The weight of each criteria was estimated based on Analytical Hierarchy Process (AHP). In multi-criteria decision analysis, 21.55 % of the total area for Wadi Nisah was classified as extremely dangerous and dangerous; 65.29 % of the total area was classified as moderate; and 13.15 % of the total area was classified as safe and very safe in flash flood hazard classes. Only 15% of Wadi Nisah has a very high potentiality for RWH and 27.7%, 57.31% of the basin has a moderate and a low or extremely low potentiality of RWH, respectively. According to the developed RWH potentiality map, two possible dam sites were proposed. The maximum height of the proposed dams, which corresponded to the cross section of dam locations, ranged from 6.2 to 9 meters; the maximum width of dams ranged from 573.48 to 725 meters; the maximum storage capacity of reservoirs, which corresponded to the distribution of topographic conditions in the surrounding area, ranged from 3976104.499 m3 to 4328509.123 m3; and the maximum surface area of reservoirs ranged from 1268372.625 m2 to 1505825.676.14 m2. These results are highly important for the decision makers for not only flash flood mitigation but also water management in the study area.

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