Assessing the Safety of Settlements from Flood Risk

Civil Engineering and Architecture, 2022

As a part of climate change; flash floods are rapidly increasing and becoming more severe, challenging more and more cities around the world. According to the recent facts published by the UN and the WHO, their risk increases particularly in low- and mid-income countries, where it exceeds the ability of communities to cope with it. This sheds the light on the importance of the community’s pre-impact conditions, which determine its vulnerability to floods. This research develops a vulnerability assessment tool and its associated methodology as an effective tool to be integrated into the strategic planning of existing cities facing flash floods. It is an indicators-based GIS tool to Assess Physical and Social vulnerability. Nuweiba city on the gulf of Aqaba-Egypt was chosen as a case study. However, it is located in an arid zone, and suffers from frequent and severe flash floods. It could be considered the effluent of Wadi Watir's main watershed (3509 km2). A GIS model has been developed to apply the Physical part of the developed assessment tool. So, Detailed data on the city’s urban structure, DEM and satellite images were integrated and processed to extract the evaluated layer for each vulnerability indicator. Then, a weighted overlay of these indicators was applied to produce the final vulnerability map. The results showed a high level of applicability for the developed model, however, the vulnerability map was compared to the available strategic plan for the city. Accordingly, several changes to the plan were recommended to achieve a more sustainable future for the city.

Civil Engineering Journal

Identifying risks in flood-prone areas is necessary to support risk management decisions. This research was conducted to establish a vulnerability model of flood hazards in the city of Pontianak. The model was based on the scoring and weighting of biophysical factors. The AHP method and logical formulations were used to establish the model. The result showed that the accuracy of the model used by AHP to determine the vulnerability of floods was 80% in Pontianak City. The accuracy of the model using logical formulations to determine the vulnerability level of a flood was 84%. The Kappa accuracy value in model 1 is 76.7%. The model of flood vulnerability explains that most of Pontianak City has a very high level of flood vulnerability, which is 31,440,568.8 m2 or 29.11% of the total research area of 108,003,319.8 m2. The vulnerable area is 29,945,485.7 m2 or 27.73%, and the less safe area is 22,126,936.3 m2 or 20.49%, with the safe area being 24,490,328.7 m2or 22.67% of the total area...

ERJ. Engineering Research Journal, 2012

GIS has gained considerable importance in engineering applications particularly in the fields of hydrology and hydraulics. The present paper assessed the risk of the Aswan High Dam, AHD breaching, numerically. Flood model was chosen and was selected to be implemented. The outflow hydrograph due to fail of AHD are considered as the output of Abdelhaleem F. study (2011). Then, SOBEK 1D2D model was implemented in order to simulate the flood wave propagation and inundation area in the Nile Valley. Geographical Information Systems, GIS tools was used to manage the input and output results, and also was used to produce a precise Digital Elevation Model, DEM to the Nile Valley, Egypt, and implemented in order to determine the banks violation sites together with the inundation of surrounding areas. So the size of expected damage of national main structures, (Railways, roads, airports, etc) within the extension of the study area was identified using GIS spatial database. The final obtained raster maps were handled and analyzed mutually with up-to-date maps of GIS thus more applicable results. The time of flood wave propagations along the Nile was calculated in order to define the time of response for emergency measures to be operated. The results could put forward to a flood management plan and could suggest evacuation plans.

International Journal of Innovative Studies in Sociology and Humanities, 2023

The study of floods is a topic of increasing interest in the field of risk management because it constitutes the most recurring natural disaster in the world that causes significant damage. Algeria is among the Mediterranean countries that are affected by sudden and unpredictable floods. According to the Algerian civil protection services, one out of three municipalities is likely to be flooded, in part or in full. In recent decades, extreme hydrological events have occurred in the arid city of M'chouneche. Their high frequency and dependence on climate change, in addition to the increasing demographic pressure on the shores of valleys, make them a cause for concern and difficult to manage. The use of empirical, hydrodynamic, or conceptual models and geographical information systems (GIS) has become a valuable approach for assessing natural hazards, especially floods. This work aims to simulate floods for a 10-year and 100-year return periods with a one-dimensional (1-D) model using HEC RAS (Hydrologic Engineering Centers River Analysis System) software, GIS (Geographic Information System), and remote sensing (RS). The result is a decision support tool for local authorities based on feedback experience from extreme hydrological events and flood frequency analysis for different return periods to identify probable flood scenarios and provide valuable decision support for emergency response and crisis management.

Jordanian Journal of Engineering and Chemical Industries, 2020

Jordan is located in an arid and semi-arid climatic zone, where about 80% of the country, known as the "Badia". Generally, this is classified as a dry or arid region. Climate change is expected to exacerbate the current aridity and scarcity of water resources in Jordan. Sudden and extreme weather events are becoming more common; this likely means longer and drier summers, more severe droughts, harsher winters, and an increase in flash floods. Jordanian Civil Defense reported that during 1963-2019, 451 people were killed and about one million people affected by flash floods. This research aims to determine the critical locations of flash floods in the Amman Zarqa Basin. This research methodology depends on using four variables (slope, vegetation cover/density, soil type/texture, and land use/cover) under the GIS environment to calculate the Flash Flood Potential Index (FFPI). This index has not been used in Jordan (up to our knowledge). Five scenarios were used in this study, based on previous reviews and the last one (scenario 5) based on Jordanian experts of flash floods in Jordan. The results show that increasing the weight of slope and land use in different FFPI equations will increase the values of FFPI. Reducing the vegetation density by 50% resulted in limited effects on the importance of FFPI. The risk level is divided into four categories (extreme, high, medium, and low) related to the FFPI values. Scenario two, which uses equal weights for all parameters, had the lowest risk level all over the area. Scenario four, which double the consequences of the slope and the land use with respect to the other two parameters. This has the highest risk level over the study area. Based on equation no. 5, which is modified based on Jordanian experts' opinion, the low-risk level covered 9.01% of the basin. Besides, the medium, high, and extreme risk levels covered 72.96%, 15.89%, and 2.14% of the study area, respectively.

Catrina: The International Journal of Environmental Sciences, 2021

In terms of flood hazards, Shalatin is the least studied of the six major coastal cities in Egypt's Red Sea Governorate. The current study intends to determine the extent to which Shalatin city is exposed to flood hazard in an attempt to address this research gap. Urban flood modeling proved to be the most effective method. All the layers required for modeling were created in ArcGIS software at the greatest possible resolution using remote sensing products and data obtained during the field investigation. Three potential flood events were modeled as one-dimensional unsteady flow using the most recent version (6.0) of the HEC-RAS programme. To quantify the extent of flooding and water depth, as well as the water velocity and flood hazard, three types of maps were created. In comparison to other cities along Egypt's Red Sea coast, the data reveal that Shalatin appears to be less prone to floods. To safeguard the most susceptible areas, two earthen dykes, each around 2000 metres long, are recommended. The current study is the first to tackle the simulation of an Egyptian city's urban flood at a resolution of up to a single building.

International Review for Spatial Planning and Sustainable Development

A flood is like a silent killer. Although small floods may appear harmless, they can be deadly when they become massive. For example, the annual damages from flooding in Pontianak, Indonesia reached US$30 million in 2015 and could increase to US$83.6 million by 2055. To counter these events, we need to assess the vulnerability of a city by making a flood risk map and comparing the current vulnerability state in 2020 and the future vulnerability state in 2050. The present study involved quantitative research using variables and measurements to indicate the vulnerability state of each district of Pontianak. The variables consisted of evacuation route efficiency and sheltering capacity, with these variables representing how easily people can be evacuated and the sufficiency of shelter, respectively. The efficiency of evacuation routes was measured by integration measures from space syntax methods, while sheltering capacity was determined by the data and simple equations. A quadrant diagram was used to record the results of both measurements and present the vulnerability. This research projected the population in 2050 and repeated the measurements to predict future changes. By comparing the flood vulnerability of Pontianak City in 2020 and 2050, this research found that Pontianak City will become more resilient against flooding. The reason for this finding is the implementation of a ring road to Pontianak City. The ring road will significantly improve the evacuation route of the city. Howeover, the capacity rate decreased, which should be addressed as a serious risk.

Journal of Water and Wastewater, 2022

Urban floods have been exacerbated by climate change, urbanization, and limited drainage of urban infrastructure. Over the past decades, they had many negative effects, including the vulnerability of key centers. The vulnerability of key urban centers through man-made hazards and natural disasters causes their inefficiency, intensifies public dissatisfaction and lack of service in accidents. In order to make key centers resilient, it is necessary to identify important centers and examine their vulnerability to various hazards and threats. Criteria and sub-criteria for grading and evaluation of assets were weighted by AHP technique in Expert Choice software and then the key centers of the city were identified. Intra-Urban and extra-Urban hydrology and modeling of rivers in Hamadan in different return periods were studied by using HEC-RAS software. Next, the results were transferred to GIS and flood risk zoning of Hamadan was determined. After entering the average sample comments in Expert Choice software, the weight of each index was determined separately, which shows that the quantitative level of utilization index has the highest weight and the economic value of the asset has the lowest weight. Finally, with the adaptation of key centers and flood risk zones in GIS, vulnerable centers were identified.

2017

The city of Batna, one of the Algerian cities, is the most exposed to flood risks, which are highly active and constitute a threat to the residents and the infrastructure. To better understand the vulnerability of this phenomenon, an approach of cartography inspired by the method of “suitability modeling” is used. This method allows us to determine the potential vulnerability levels of the study zone; therefore, we need to consider several criteria: socioeconomic factors like density of population, land use, and also physical criteria such as permeability, flow direction, and the like. Each of these various criteria was built on a database, which constituting an important element for building a model that helps us determine the vulnerable zones by using various GIS applications. The applied approach that depends on how the criteria are suitable give us 4 different levels of vulnerability in Batna, which are as follows: high vulnerability, 13% of the city’s total surface, average vul...

In this paper we analyse urban and regional growth trends by using dynamic spatial models. The objective of this approach is twofold: on the one hand to monitor sustainable development trends and on the other hand to assess flood risk in urban areas. We propose the use of future urban scenarios in order to forecast the effects of urban and regional planning policies. In the last 20 years the extent of built-up areas in Europe has increased by 20%, exceeding clearly the 6% rate of population growth over the same period. This trend contributes to unsustainable development patterns, and moreover, the exposure to natural hazards is increasing in large regions of Europe. The paper is organised in two parts. In the first part we analyse a study case in Friuli-Venezia Giulia (FVG) Region in northern Italy. We analyse several spatial indicators in the form of maps describing population growth and patterns, and the historical growth of built-up areas. Then we show the results of a dynamic sp...

2013

Urban drainage managers and professional are faced with uncertain socio-economic and climate futures, as cities and urban water systems are under pressure due to a number of trends such as population growth, economic growth, and increased urbanisation. A way of managing this uncertainty is to develop and apply water management strategies that can cope with a range of futures. There are an infinite number of possible futures, and therefore, it is useful for planners to develop a limited number of scenarios, which describe selected coupled socio-economic and climate futures for a city. These scenarios can then aid stakeholders in their decision making processes. This paper describes the key challenges of scenario development and the methodology used in the CORFU project.

12th International Space Syntax Symposium 12SSS, Beijing: Beijing Jiaotong University, China, 2019

Egypt is well known for establishing new cities in the desert to extend urban areas out of its congested valleys, mostly in the Greater Cairo region. Some of these new cities face strong challenges when potential flooding is not considered as a vital aspect in the master planning development phases. A new administrative capital (NAC) city is currently under construction in the eastern desert region of Greater Cairo. Topographically a slope runs from east (the Suez and Red Sea governorates) to west (the Nile valley, Greater Cairo). Between the NAC and Cairo is another recent city development, named New Cairo city, which faced flooding in 2018. The cause of this problem was not disregard for potential floods in the initial masterplan, but rather it was the construction of buildings within the flood area resulting from the Minister of Housing selling off building plots between 2003 and 2009. This caused a massive flooding impact on buildings, interruptions to the street network and traffic flow, and splits in the urban structure to create various isolated entities. This paper proposes a methodological approach that combines different layers of analysis to investigate the impact of flood risks on the urban structure of new cities and highlight the importance of considering that risk while the masterplan is in the development process. It overlays flood simulation models, syntactic analysis, topographical and flood studies and compares the results in two different scenarios: under average rainfall versus full flooding. The case study is based on the NAC. Combining different analytical methods helps to identify urban zones under flood risk precisely and to propose solutions. The resulting remedy to solve the problem in the NAC would be to: (1) identify the essential locations for placing necessary reservoirs and catchments, and (2) widen the green valley (green belt). These proposed solutions can be directed to the municipalities and planners to consider flood risks while developing the masterplan in its initial phases or during ongoing construction phases when remedies can still be included in the project's phasing. Hence there are two targets for further research: (1) how feasible amendments to the masterplan may be made during the construction phases, and (2) how regulations can be developed for flood risk zones to protect buildings from massive loss.

2007

A 2D-hydraulic flood propagation models require accurate elevation data. One of the main problems is frequent changes of land use in major cities, where frequent updating of the digital terrain model (DTM) for flood modelling might be needed. On the other hand the assessment should be based on realistic flood hazard indicator that would help to reflect the real impact of urban development on the surrounding areas. This paper presents an example of assessing the impact of flood for future developments in Naga City, the Philippines. The elevation data is constructed through integrating various elevation data derived from many sources. The development impact assessment begins with the detailed observation on changes in flood characteristics. This is supported by the analyses on the community-based flood risk perception and investigation on changes of flood hazard (based on the flood velocity and depth).

Recent Advances in Flood Risk Management, 2019

Floods are increasingly occurring around the world more often, this implies analysing the risks connected to both human health and the environment, and to infrastructure and properties. The objective is to establish areas susceptible to flooding and their impact on the population through the effects on the unit of analysis "housing". To simulate the floods and map the affected areas, the FluBiDi 2D model was used. Two conditions for one urban zone analysed within the Mexico Valley were compared: (a) with the current hydraulic infrastructure and (b) with the application of rectification of channels. The available information was the discharge getting into the catchment and the total of homes in 2015. Projections for 20-year and 50-year planning horizon were considered, and for the 50 years, an evaluation of a non-structural measure was applied. Results show that under the current infrastructure, the flood simulated had a flow depth of 20 cm, decreasing to 5 cm average with rectification of channels, and a decrement of 45% of the cost of housing risk. Applying the both structural and non-structural measures, the cost of vulnerable housing was reduced until 94%, thus, this a trustworthy tool for decision-making in urban developments.

Water, MDPI, 2019

This study aims to assess the impact of flash floods in theWadi Nu’man basin on urban areas, east of Mecca, which are subjected to frequent floods, during the period from 1988–2019. By producing and analyzing the maps of the regions, an integrated approach to geomatics and hydraulic modelling is employed. The following maps are used: Flood-prone urbanity from 1988–2019, a flood risk map ofWadi Nu’man based on a risk matrix map, and a map of the proposed protection measures and alternatives in the study area. In order to achieve these goals, changes in the land use in the Wadi Nu’man basin were monitored by analyzing successive satellite images, taken by the US satellite, Landsat, in 1988, 1998, 2013, and 2019. Using a supervised classification, with the maximum likelihood method of ERDAS IMAGINE 2016, GIS was used in the production and analysis of soil maps, and geological and hydrological groups of drainage basins, as well as the hydrological model (HEC-HMS), were applied in calculating the hydrograph curve of the Wadi Nu’man basin. The flood water volumes and flow rates were estimated based on the SCS unit hydrograph, and the rain depth was analyzed and estimated for di erent periods. The hydraulic modeling program (HEC-RAS) was employed, when developing a two-dimensional model to calculate the speed, depth, and spread of the flood, in order to apply the risk matrix method. The recommendations based on this study give priority to the implementation of a flood prevention plan and the protection of infrastructure by maintaining the existing flood drainage facilities and establishing new drainage facilities to protect lives, property, and infrastructure