Management of hazard of flooding in arid region urban agglomeration using HEC-RAS and GIS software: The case of the Bechar's city

Abstract During the last few years, the City of Bechar in Algeria has witnessed some extreme events, such as the great flood of the year 2008 in which an exceptional amount of rain was recorded with a flow rate of 830 m3∙s−1 (hwater = 4 m, b = 200 m); similar flooding also occurred in 2012 and 2014. The problem is that most of the City of Bechar has an urban sprawl that extends to the banks of Wadi Bechar, which represents a huge risk for the lives of the inhabitants of the region. The present work aims to assess the flood risk through flood hazard mapping. This method consists in determining the flow rates for the return periods of 25 years (Q25 = 388.6 m3∙s−1, hwater = 3.5 m, b = 200 m, Sspot = 55.35 ha), 50 years (Q50 = 478.3 m3∙s−1, hwater = 5 m, b = 200 m, Sspot = 66.48 ha) and 100 years (Q100 = 567.3 m3∙s−1, hwater = 7 m, b = 200 m, Sspot = 133 ha). For this, it is necessary to adjust the flow rates using Gumbel law along with some computer supports such as HEC-RAS, HEC-GeoRAS and ArcGis for mapping the event. Finally, this work enables us to determine the zones exposed to risk of flooding and to classify them according to the flood water height.

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Flood Hazard Spatialization Applied to The City of Batna: A Methodological Approach

Engineering, Technology & Applied Science Research ◽

10.48084/etasr.3429 ◽

2020 ◽

Vol 10 (3) ◽

pp. 5748-5758

Author(s):

N. Harkat ◽

S. Chaouche ◽

M. Bencherif

Keyword(s):

Flood Hazard ◽

Methodological Approach ◽

Digital Terrain Model ◽

Hydraulic Modeling ◽

Flood Hazards ◽

Return Periods ◽

Suggested Model ◽

Flood Flows ◽

Analysis System ◽

The City

Flood flows can cause destruction to properties and infrastructure or even cost human lives. Batna is an Algerian city that is highly exposed to the risk of flooding, with an average of one flood every three to four years. The current methods utilized to analyze flood hazards are limited to the hydrology of the watershed. Limiting the analysis of flood hazards could mislead the decision-makers from proper management of such risks. The objective of the current study is to propose a simplified flood hazard model called HEC RAS-DTM (Hydrologic Engineering Centers River Analysis System (HEC RAS)-Digital Terrain Model (DTM)) and to evaluate it utilizing data gathered from the hydrological context and the hydraulic modeling of Batna city. The model entails two distinct phases. Initially, it attempts to use descriptive statistical methods based mainly on frequency analysis, which consists of studying flood flows in order to determine the probability of future flood occurrence. The analysis of the hydrological context of the city of Batna has revealed that peak flows from stream floods have been predicted at various return periods. Subsequently, HEC RAS was deployed to produce hydraulic modeling in order to extract the water heights and speeds corresponding to these expected flows. These data, along with DTM, are crucial for the spatialization of flood hazards. The hydraulic modeling and simulation using HEC-RAS and Geographic Information System (ArcGIS) of water flow at the two main valleys, Oued Batna and Oued El Gourzi, allowed predicting the extent of flooding that could occupy a large part of the city. The mapping of the flood hazard revealed the sectors that would be most exposed. The results obtained from the suggested model confirm that a significant portion of the city of Batna remains vulnerable to floods in relevance with the predicted flood return periods. The suggested model has indicated significant growth in flood locality. Additionally, the model was proved to be efficient for the analysis of flood flows, and it could easily substitute conventional analysis methods. Further studies or investigations are advised in order to replicate the study in different contexts. The article entails suggestions for properly managing flood risks. Future studies on flood risk alleviation in Batna city could be likewise considered.

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Effects of return periods on flood hazard mapping: an analysis of the UFSC Campus Basin, Florianópolis city, Brazil

RBRH ◽

10.1590/2318-0331.262120200161 ◽

2021 ◽

Vol 26 ◽

Author(s):

Leonardo Romero Monteiro ◽

Camyla Innocente dos Santos ◽

Masato Kobiyama ◽

Cláudia Weber Corseuil ◽

Pedro Luiz Borges Chaffe

Keyword(s):

Urban Areas ◽

Flood Hazard ◽

Small Variation ◽

Hazard Mapping ◽

Hazard Map ◽

Return Periods ◽

Test Bed ◽

Mean Velocity ◽

Hazard Degree ◽

Logarithmic Relationship

ABSTRACT The development of urban areas exacerbates flood risk by increasing both runoff and the exposure of population and infrastructure. In this study, we highlight the importance of return period choice on flood hazard degree and flood hydraulics characteristics. We use the UFSC campus basin as a test bed and combine a hydrological and a hydrodynamic model to define the flood hazard intensity and flood hazard degree. Six hazard intensity maps were elaborated using different return periods (2, 10, 25, 50, 100 and 500-years) that characterize low and high recurrence scenarios. The low recurrence hazard map can be ideal to verify hazard effects on buildings, while the high recurrence hazard map helps to identify people security. All variables related to the rainfall effect and its consequences (e.g. rainfall intensity, flood mean velocity, and total flood area) follow a logarithmic relationship, with a small variation for higher return periods. We highlight how different return periods can influence flood hydraulics and flood hazard and should therefore be considered in flood hazard mapping.

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Mapping of GIS-Flood Hazard Using the Geomorphometric-Hazard Model: Case Study of the Al-Shamal Train Pathway in the City of Qurayyat, Kingdom of Saudi Arabia

Geosciences ◽

10.3390/geosciences10090333 ◽

2020 ◽

Vol 10 (9) ◽

pp. 333

Author(s):

Ashraf Abdelkarim ◽

Seham S. Al-Alola ◽

Haya M. Alogayell ◽

Soha A. Mohamed ◽

Ibtesam I. Alkadi ◽

...

Keyword(s):

Saudi Arabia ◽

Drainage Basin ◽

Flood Hazard ◽

Hazard Model ◽

Hazard Mapping ◽

Flood Hazards ◽

Drainage Basins ◽

Kingdom Of Saudi Arabia ◽

High Flood ◽

The City

Drainage basins in dry and semiarid environments are exposed to sudden, irregular flooding that poses a threat to urban areas and infrastructure. The associated risk is exacerbated by land use changes. Geomorphometric analyses of drainage basins based on geographic information systems (GIS) are essential tools for assessing conceptual flood hazards. Geomorphological data extracted from high-precision digital elevation models (DEMs) provide valuable information for modeling the geomorphic, surface classifications of the earth, and for flood hazard mapping. This study aimed to develop an integrative approach to the mapping of flood hazards along the Al-Shamal train pathway in the city of Qurayyat in the Kingdom of Saudi Arabia (KSA) using GIS and hazard modeling for geomorphological ranking. Furthermore, we propose strategic solutions to provide mitigation and protection from negative impacts with the aim of improving the level of awareness of flood geomorphology. The hazard model of geomorphological ranking was used in mapping and calculating the degree of hazards using 24 geomorphometric criteria. These criteria were divided into formal criteria, terrain criteria, and criteria related to the drainage network. The results of the study revealed that the drainage sub-basins are exposed to flood hazards along the Al-Shamal train pathway in the city of Qurayyat. The very high flood hazard constituted 4228.3 km2, accounting for 70.3% and 65.7%, respectively, of the drainage basins of the wadis of Makhrouq and Bayer. The high flood hazard represented 61% (4712.4 km2) of the basin of the wadis of Sarmadaa. The medium flood hazard was concentrated in the drainage basin of the wadi of Hasidah, accounting for nearly 57.7% (1271.3 km2). The very low flood hazard was present in 46.5% of the drainage basin of the wadis of Hasidah Umm Nakhla, accounting for an area of 799.4 km2. The methodology applied in this study can be used in the estimation of flood hazards in different drainage basins throughout Saudi Arabia and in similar arid regions.

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Topography- and nightlight-based national flood risk assessment in Canada

10.5194/hess-2016-524 ◽

2016 ◽

Author(s):

Amin Elshorbagy ◽

Anchit Lakhanpal ◽

Bharath Raja ◽

Serena Ceola ◽

Alberto Montanari ◽

...

Keyword(s):

Flood Risk ◽

Flood Hazard ◽

Hazard Mapping ◽

Hazard Map ◽

Flood Risk Assessment ◽

Risk Map ◽

National Scale ◽

Digital Elevation ◽

The City ◽

Flood Risk Map

Abstract. In Canada, flood analysis and water resource management, in general, are tasks conducted at the provincial level; therefore, unified national-scale approaches to water-related problems are uncommon. In this study, a national-scale flood risk assessment approach is proposed and developed. The study focuses on using global and national datasets available at reasonably fine resolutions to create flood risk maps. First, a flood hazard map of Canada is developed using topography-based parameters derived from digital elevation models namely Elevation Above Nearest Drainage (EAND) and Distance From Nearest Drainage (DFND). This flood hazard mapping method is tested on a smaller area around the city of Calgary, Alberta, against a flood inundation map produced by the City using hydraulic modeling. Second, a flood exposure map of Canada is developed using a land-use map and the satellite-based nightlight luminosity data as two exposure parameters. Third, an economic flood risk map is produced, and subsequently overlaid with population density information to produce a socioeconomic flood risk map for Canada. All three maps of hazard, exposure, and risk are classified into five classes, ranging from very low to severe. A simple way to include flood protection measures in hazard estimation is also demonstrated using the example of the city of Winnipeg, Manitoba. This could be done for the entire country if information on flood protection across Canada were available. The evaluation of the flood hazard map shows that the topography-based method adopted in this study is both practical and reliable for large-scale analysis. Sensitivity analysis regarding the resolution of the digital elevation model is needed to identify the resolution that is fine enough for reliable hazard mapping, but coarse enough for computational tractability. The nightlight data are found to be useful for exposure and risk mapping in Canada; however, uncertainty analysis should be conducted to investigate the effect of the overglow phenomenon on flood risk mapping.

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Topography- and nightlight-based national flood risk assessment in Canada

Hydrology and Earth System Sciences ◽

10.5194/hess-21-2219-2017 ◽

2017 ◽

Vol 21 (4) ◽

pp. 2219-2232 ◽

Cited By ~ 10

Author(s):

Amin Elshorbagy ◽

Raja Bharath ◽

Anchit Lakhanpal ◽

Serena Ceola ◽

Alberto Montanari ◽

...

Keyword(s):

Flood Risk ◽

Flood Hazard ◽

Hazard Mapping ◽

Hazard Map ◽

Flood Risk Assessment ◽

Risk Map ◽

National Scale ◽

Digital Elevation ◽

The City ◽

Flood Risk Map

Abstract. In Canada, flood analysis and water resource management, in general, are tasks conducted at the provincial level; therefore, unified national-scale approaches to water-related problems are uncommon. In this study, a national-scale flood risk assessment approach is proposed and developed. The study focuses on using global and national datasets available with various resolutions to create flood risk maps. First, a flood hazard map of Canada is developed using topography-based parameters derived from digital elevation models, namely, elevation above nearest drainage (EAND) and distance from nearest drainage (DFND). This flood hazard mapping method is tested on a smaller area around the city of Calgary, Alberta, against a flood inundation map produced by the city using hydraulic modelling. Second, a flood exposure map of Canada is developed using a land-use map and the satellite-based nightlight luminosity data as two exposure parameters. Third, an economic flood risk map is produced, and subsequently overlaid with population density information to produce a socioeconomic flood risk map for Canada. All three maps of hazard, exposure, and risk are classified into five classes, ranging from very low to severe. A simple way to include flood protection measures in hazard estimation is also demonstrated using the example of the city of Winnipeg, Manitoba. This could be done for the entire country if information on flood protection across Canada were available. The evaluation of the flood hazard map shows that the topography-based method adopted in this study is both practical and reliable for large-scale analysis. Sensitivity analysis regarding the resolution of the digital elevation model is needed to identify the resolution that is fine enough for reliable hazard mapping, but coarse enough for computational tractability. The nightlight data are found to be useful for exposure and risk mapping in Canada; however, uncertainty analysis should be conducted to investigate the effect of the overglow phenomenon on flood risk mapping.

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Regional Flood Hazard Mapping in Murshidabad, West Bengal

International Journal of Scientific Research ◽

10.15373/22778179/feb2013/132 ◽

2012 ◽

Vol 2 (2) ◽

pp. 391-393

Author(s):

Swati Mollah ◽

Keyword(s):

West Bengal ◽

Flood Hazard ◽

Hazard Mapping

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Scoping of Flood Hazard Mapping Needs for Lincoln County, Maine

Open-File Report ◽

10.3133/ofr20071130 ◽

2007 ◽

Author(s):

Charles W. Schalk ◽

Robert W. Dudley

Keyword(s):

Flood Hazard ◽

Hazard Mapping ◽

Lincoln County

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Mental Health and the City in the Post-COVID-19 Era

Sustainability ◽

10.3390/su13147533 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7533

Author(s):

Jakub Bil ◽

Bartłomiej Buława ◽

Jakub Świerzawski

Keyword(s):

Mental Health ◽

Spatial Structure ◽

Urban Sprawl ◽

Mental Health Treatment ◽

Interpersonal Relations ◽

Urban Structure ◽

Spatial Effects ◽

Development Goals ◽

The City

The article describes the risks for the mental health and wellbeing of urban-dwellers in relation to changes in the spatial structure of a city that could be caused by the COVID-19 pandemic. A year of lockdown has changed the way of life in the city and negated its principal function as a place of various meetings and social interactions. The danger of long-term isolation and being cut-off from an urban lifestyle is not only a challenge facing individuals, but it also creates threats on various collective levels. Hindered interpersonal relations, stress, and the fear of another person lower the quality of life and may contribute to the development of mental diseases. Out of fear against coronavirus, part of the society has sought safety by moving out of the densely populated city centres. The dangerous results of these phenomena are shown by research based on the newest literature regarding the influence of COVID-19 and the lockdown on mental health, urban planning, and the long-term spatial effects of the pandemic such as the urban sprawl. The breakdown of the spatial structure, the loosening of the urban tissue, and urban sprawl are going to increase anthropopressure, inhibit access to mental health treatment, and will even further contribute to the isolation of part of the society. In addition, research has shown that urban structure loosening as a kind of distancing is not an effective method in the fight against the SARS-COV pandemic. Creating dense and effective cities through the appropriate management of development during and after the pandemic may be a key element that will facilitate the prevention of mental health deterioration and wellbeing. It is also the only possibility to achieve the selected Sustainable Development Goals, which as of today are under threat.

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