Flood Risk Analysis Research Articles

Analysis of the Risk of Coastal Flooding Due to Rising Sea Levels in Ría of Arosa (Pontevedra, Spain)

In this study, an analysis of coastal vulnerability and flood risk due to sea-level rise was conducted in the southern margin of the Ría of Arosa, Pontevedra (Spain), which is an area of urban impact and tourist activity. The vulnerability index was calculated using the following parametric maps: lithology, geomorphology, slope, elevation, distance, coastline change, significant wave height, sea level, and extreme tidal range. This vulnerability index was validated through the results obtained from the flood risk analysis, developed for different temporal and extreme scenarios (Xa—present, Xb—100 years, Xc—500 years, Xd—1000 years, Xe—storm, and Xf—tsunami). These analyses were performed using Geographic Information System and remote sensing techniques, spatial analysis, interpolation processes, and geostatistical analysis. The results of the analysis show the vulnerable areas and areas at high risk of coastal flooding, with the urbanized area exposed to a risk of 7.45 km2. Thus, this study contributes to designing appropriate management for the coastline of the southern margin of the Ría of Arosa in the event of a flood.

Flood risk assessment of subway stations based on projection pursuit model optimized by whale algorithm: A case study of Changzhou, China

With rapid modernization, traffic jams have become a part of people's daily lives. An increasing number of cities have begun to build subways to solve this problem. This study focuses on the flood risk analysis of subway stations, which is often overlooked. However, such disasters cause serious mass casualties and huge property losses. Therefore, this is of great concern. This study applies the method of projection pursuit model optimized by whale algorithm to evaluate the flood disasters of subway stations. The results showed that the flood risk level of 11 subway stations was very low, that of 21 subway stations was low, that of seven subway stations was moderate, and that of one subway station was high. Compared to the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method, the application of the projection pursuit model based on the whale algorithm has higher precision and better global searchability. The main contribution of this study is to provide a new method and idea for the field of flood risk assessment of subway stations, and to provide a scientific model and reference for local rail companies. This study used the whale algorithm to optimize the projection pursuit model and applied it to the flood risk assessment of subway stations. This is an innovation in this field that has strong engineering application significance.

Urbanization and flood risk analysis using geospatial techniques.

This research investigates the relationship between urbanization as a land use/land cover change and the increased flood disasters in Accra. Understanding this relationship will provide evidence for urban development planners, policy makers and flood managers to coordinate in responding to the problems effectively. This study maps and analyzes the changes in urbanization from 1991 to 2015. The research reviews the trends of flood events in Greater Accra and analyzes the relationship between the pattern of urbanization and the increase in flood disaster events from 1991 to 2015. The research revealed that there was an increase in urban land use/land cover change of up to 95.51% and 129.14% in the periods 1991-2002 and 2002-2015 respectively. The pattern of urbanization took place in an unplanned style, where physical developments in waterways became high. The findings show that the pattern of flood disasters increased from 1991 to 2015 with evidence showing two years having repeated flood events.

Extraction of Spatiotemporal Distribution Characteristics and Spatiotemporal Reconstruction of Rainfall Data by PCA Algorithm

Scientific analyses of urban flood risks are essential for evaluating urban flood insurance and designing drainage projects. Although the current rainfall monitoring system in China has a dense station network and high-precision rainfall data, the time series is short. In contrast, historical rainfall data have a longer sample time series but lower precision. This study introduced a PCA algorithm to reconstruct historical rainfall data. Based on the temporal and spatial characteristics of rainfall extracted from high-resolution rainfall data over the past decade, historical (6 h intervals) rainfall spatial data were reconstructed into high-resolution (1 h intervals) spatial data to satisfy the requirements of the urban flood risk analysis. The results showed that the average error between the reconstructed data and measured values in the high-value area was within 15% and in the low-value area was within 20%, representing decreases of approximately 65% and 40%, respectively, compared to traditional interpolation data. The reconstructed historical spatial rainfall data conformed to the temporal and spatial distribution characteristics of rainfall, improved the granularity of rainfall spatial data, and enabled the effective and reasonable extraction and summary of the fine temporal and spatial distribution characteristics of rainfall.

HYDROLOGICAL MODELLING FOR FLOOD RISK ANALYSIS IN SELECTED SUB COUNTIES, NAIROBI, KENYA

HYDROLOGICAL MODELLING FOR FLOOD RISK ANALYSIS IN SELECTED SUB COUNTIES, NAIROBI, KENYA

GIS Based approach of flood Vulnerability Assessment and risk Analysis in Bharghavi River Basin -: A case study on Rajas Panchayat of Balipatna Block, Khurda, Odisha, India

GIS Based approach of flood Vulnerability Assessment and risk Analysis in Bharghavi River Basin -: A case study on Rajas Panchayat of Balipatna Block, Khurda, Odisha, India

Assessing the impact of climate change on sediment discharge using a large ensemble rainfall dataset in Pekerebetsu River basin, Hokkaido

Increased rainfall associated with climate change can increase sediment discharge. The supply of fine sediment from slope failures inhibits bed armoring of mountain rivers and increases sediment discharge to the downstream reaches. Floods without slope failures lead to bed erosion and armoring and may ultimately decrease sediment discharge. Thus, it is important to consider sediment discharge from slope failure and bed erosion as factors affecting sediment production. Climate change affects not only the rainfall amount, but also the temporal rainfall pattern; consequently, the pattern affects the sediment production factors and the amount of sediment discharge. However, changes in sediment discharge due to climate change based on sediment production sources have not yet been clarified. In this study, we statistically analyzed 1200 results simulated using a physics-based sediment runoff model to assess the impact of changes in temporal rainfall patterns on sediment discharge and sediment production sources in the Pekerebetsu River Basin. In the simulations, we used the rainfall predicted in d4PDF (Database for policy decision-making for future climate change), a large ensemble climate simulation database at 5 km and 20 km resolutions. Our results showed that the climate-driven increase in sediment discharge was considerably larger than that of rainfall. An increase in short-term heavy rainfall increased the supply of fine sediments from slope failure. This resulted in the suppression of bed armoring and a large increase in sediment discharge. Thus, the increase in sediment discharge is not only caused by an increase in rainfall but also by changes in temporal rainfall patterns and sediment production factors. The sediment discharge calculated for the 20 km resolution climate projection was nearly one order of magnitude smaller than that for the 5 km resolution. This suggests that the 20 km resolution climate projections do not adequately represent orographic rainfall in the mountains and thus, do not adequately reproduce extreme sediment discharge events. An increased sediment supply causes bed aggradation and decreases the river conveyance capacity of the downstream channel. The model developed in this study will contribute to flood risk analysis and flood control planning for increased rainfall due to climate change.

Flood risk analysis and zoning and its relationship with vegetation in Qirokarzin County

Flood risk analysis and zoning and its relationship with vegetation in Qirokarzin County

Investigating optimal 2D hydrodynamic modeling of a recent flash flood in a steep Norwegian river using high-performance computing

Abstract Efficient flood risk assessment and communication are essential for responding to increasingly recurrent flash floods. However, access to high-end data center computing is limited for stakeholders. This study evaluates the accuracy-speed trade-off of a hydraulic model by (i) assessing the potential acceleration of high-performance computing in PCs versus server-CPUs and GPUs, (ii) examining computing time evaluation and prediction indicators, and (iii) identifying variables controlling the computing time and their impact on the 2D hydrodynamic models' accuracy using an actual flash flood event as a benchmark. GPU-computing is found to be 130× and 55× faster than standard and parallelized CPU-computing, respectively, saving up to 99.5% of the computing time. The model's number of elements had the most significant impact, with <150,000 cells showing the best accuracy-speed trade-off. Using a PC equipped with a GPU enables almost real-time hydrodynamic information, democratizing flood data and facilitating interactive flood risk analysis.

DEVELOPMENT OF FLOOD RISK REDUCTION INVESTMENT STRATEGIES THROUGH GLOBAL FLOOD RISK TOOL AND APPLICATION OF ADAPTATION PATHWAYS

Flooding is an issue of growing concern worldwide. Cities around the world are threatened by sea level rise, land subsidence as well as extreme river discharges and intensified precipitation during short periods of time. The interaction of these phenomena potentially causes severe flood problems. In addition, cities are often densely populated centres with high socio-economic development and sophisticated networks of water-related infrastructure. Hence, the impact and damage of flooding can be significant and very costly. In addition to climate change and socio-economic growth, many cities are sinking as a result of land subsidence. In response to these issues, Royal HaskoningDHV has been developing the Global Flood Risk Tool (GFRT). The GRFT is Royal HaskoningDHV’s cloud-based platform that delivers accurate and comprehensible flood risk analysis and recommends strategic investment proposals to reduce risk on losing lives and economic damages to the society, infrastructure, industries and businesses.

Spatial Modeling through GIS Analysis of Flood Risk and Related Financial Vulnerability: Case Study: Turcu River, Romania

The present study is part of the context in which Romania adopted the European Parliament Directive 2007/60/EC on flood risk assessment and management. Therefore, the aim of this research is to assess the risk induced by a hydrological hazard, expressed by a financial value estimation, for the Turcu River in the northern sector of the Bran–Dragoslavele transcarpathian corridor (Romania), an important tourist axis where the pressure on land has increased considerably. As a result, the intra-village areas of Moieciu de Sus, Cheia, Moieciu de Jos, Bran and Tohanu Nou have also expanded into areas vulnerable to flooding. There are currently no studies on the areas potentially affected as well as the extent of the possible damage. For this reason, we proceeded to model the water level corresponding to the maximum flow value with a probability exceeding 1%, using HEC-RAS and ArcGIS software. The results of the implementation of the spatial analysis model resulted in the delineation of the floodplain and the assessment of the potential financial loss related to the minimum market value of the land with the related real estate infrastructures. The research reveals that in the 1% band area (78.7841 ha) with water depth > 0.5 m, more than 433 infrastructures are at high risk of flooding, most of them with high real estate value, i.e., 5.61 km of roads for which a cost of EUR 3,402,666.90 was calculated for restoration. A knowledge of financial vulnerability to flooding becomes important for the community; local authorities involved in making decisions for insuring real estate at risk and planning/managing investments work to prevent/combat the effects of flooding.

Innovative remote sensing methodologies and applications in coastal and marine environments

ABSTRACT Remote sensing (RS) technologies are extensively exploited by scientists and a vast audience of local authorities, urban managers, and city planners. Coastal regions, geohazard-prone areas, and highly populated cities represent natural laboratories to apply RS technologies and test new methods. Over the last decades, many efforts have been spent on improving Earth’s surface monitoring, including intensifying Earth Observation (EO) operations by the major national space agencies. They oversee to plan and make operational constellations of satellite sensors providing the scientific community with extensive research and development opportunities in the geoscience field. For instance, within this framework, the European Space Agency (ESA) and the Ministry of Science and Technology of China (MOST) have sponsored, since the early 2000s, the DRAGON initiative jointly carried out by the European and Chinese RS scientific communities. This manuscript aims to provide a synthetic overview of some research activities and new methods recently designed and applied and trace the route for further developments. The main findings are related to i) the analysis of flood risk in China, ii) the potential of new methods for the estimation and removal of ground displacement biases in small-baseline oriented interferometric Synthetic Aperture Radar (SAR) methods, iii) the analysis of the inundation risk in low-lying regions using coherent and incoherent SAR methods; and iv) the use of SAR-based technologies for marine applications.

Locating flood susceptible areas in Sabah Al-Ahmed city, Kuwait

In Kuwait, about 111 ​mm of heavy rainfall occurred overnight in 6 ​hours on the 6th of November, 2018, caused flash floods in several areas. This study deals with the preparation of flood risk maps for Sabah Al Ahmed city by using the digital elevation model (DEM) and geographic information system (GIS) tools. Secondly, the detection of areas at risk from flash floods was done using the hydrological method. Using hydrological methods of GIS tools, the present work started with fill, flow direction, flow accumulation, basin, stream link, stream order, and stream density. In addition, quantitative descriptions of watershed morphology were used, such as the length/width ratio which was 2.64, indicating that the watershed was slightly rounded. The form factor was calculated at 0.37, indicating an inconsistent shape. The relief ratio was 0.03, indicating it was low relief. As a result, the most detected channels were the seventh, sixth, and fifth stream orders. In addition, the stream morphological equations yielded a texture ratio of 48.6 ​km, indicating a smooth texture. The bifurcation ratio was 3.12, indicating that the surface runoff had a high velocity. Also, the drainage density was 3.7 ​km/km2, and the stream frequency was 7.2 streams/km2. The watershed had moderate texture. Finally, the flood risk map showed that the study area was a very high-risk area with 1.1% of the watershed. The GIS was used in a flood risk analysis due to the potential risk it posed on people, buildings, and infrastructure in the affected areas.

Human displacements, fatalities, and economic damages linked to remotely observed floods

We present a new open source dataset FLODIS that links estimates of flood-induced human displacements, fatalities, and economic damages to flooded areas observed through remote sensing. The dataset connects displacement data from the Internal Displacement Monitoring Centre (IDMC), as well as data on fatalities and damages from the Emergency Events Database (EM-DAT), with the Global Flood Database (GFD), a satellite-based inventory of historic flood footprints. It thereby provides a spatially explicit estimate of the flood hazard underlying each individual disaster event. FLODIS contains two datasets with event-specific information for 335 human displacement events and 695 mortality/damage events that occurred around the world between 2000 and 2018. Additionally, we provide estimates of affected population, GDP, and critical infrastructure, as well as socio-economic indicators; and we provide geocoding for displacement events ascribed to other types of disasters, such as tropical cyclones, so that they may be linked to corresponding hazard estimates in future work. FLODIS facilitates integrated flood risk analysis, allowing, for example, for detailed assessments of local flood-damage and displacement vulnerability.

Analysis of Flood Hazards and Risk in the Sirimau District Ambon City

This study aims to target the threat and risk of flooding in Sirimau District, Ambon City from a multi-criteria perspective using a Geographic Information System (GIS). Important flood hazard characteristics include land use, elevation, slope, distance from rivers, soil, and rainfall. Two risk factors, namely population density and land use as well as flood hazard characteristics are used in flood risk analysis. Map aggregation procedure for flood risk and hazard analysis uses the Weighted Linear Combination (WLC) approach. The results of the flood hazard at the study site revealed that the flood hazard category was very high and high, namely 12.26%, and the flood hazard category was very low and low, namely 87.84% and only. The results of the flood risk in the research location revealed that the flood risk with very high and high-risk categories was around 17.28%, and very low and flood low-risk categories (82.77%). This is because the Sirimau District is mostly dominated by hilly and mountainous areas.

Sand dune movement and flooding risk analysis for the pyramids of Meroe, Al Bagrawiya archaeological site, Sudan

The pyramids of Meroe are a significant archaeological place at the Al Bagrawiya archaeological site (Sudan) with hundreds of pyramids dating back to the kingdom of Kush (1070 BC–550 AD). In this area, winds, heavy rains, and flooding events are the main geohazards that need assessments and solutions because pyramids are subjected to an accumulation of sand dunes around them and the risk of flooding, affecting their durability. This research aims to assess the impacts of sand dunes on the stability of pyramid structures in addition to assessing the risk of flooding using satellite image observations, and damage and decay assessments of pyramid building materials were carried out through digital mapping. The results from satellite image analysis and monitoring showed that sand dunes along with heavy rains and flooding are the main decay factors, causing the collapse, disintegration, crumbling, alveolarization, loss of materials, and cracking of the sandstone ashlars, detecting an increase in deterioration, even considering only the last three decades.

Climate Change Flood Risk Analysis: Application of Dynamical Downscaling and Hydrological Modeling

Floods are a recurring natural phenomenon during the rainy season in many Brazilian municipalities. Nevertheless, shifts in weather patterns have contributed to an increased incidence of these events in urban areas, where their impact can be amplified by the way the surrounding catchment is occupied. Hence, the present study sought to evaluate the susceptibility of the urban drainage infrastructure in João Monlevade, Brazil, to the effects of climate change by undertaking a comprehensive assessment of the Carneirinhos catchment, including its morphometric characteristics. For this purpose, we employed a hydrological model driven by regional rainfall projections from a high-resolution climate model (HadGEM2-ES downscaled to 5 km resolution) under the Representative Concentration Pathways (RCP8.5) scenario. Several combinations of rainfall occurrence were simulated, incorporating temporal aspects (different durations and return times), as well as spatial aspects (concentrated and distributed rainfall within the catchment). The results showed that the area of exposed soil in the Carneirinhos catchment experienced an increase of more than 140% from 2016 to 2019, favoring runoff surface and evaporation, which contributed to the increase in the number of flood events in the region. In addition, only 1 of the 56 heavy rainfall event simulations performed did not exceed the capacity of the macro drainage gallery.

Evaluation of Birecik Basin Flood Detection with GIS Assisted AHP Methods

In addition to the uncontrolled and rapid urbanization, irregular rainfall causes natural calamities like overflood. In an effort to stop the loses caused by these floods and to reduce their damage, it is needful to model the streams made in areas with intense urbanization and creating flood maps, which will create a suitable environment for investigations. It is vitally important to work on the computation of flood flows and the making distribution maps. Birecik basin hydrological and hydraulic model was created in this context. Data such as basin area, elevation, slope, relief, land use, soil type and stream paths were modeled in ArcMap 10.2 environment. Then, HEC-GeoRAS and Hec-Ras techniques were used for hydrological and hydraulic modeling, respectively. Birecik reclamation creek was approached holistically from a geographical point of view, and the factors affecting the flood (such as precipitation, slope, land use-vegetation, soil, proximity to river networks) were ranked among themselves. These were reclassified according to the data obtained in the AHP application and a flood risk analysis map was created in the Geographical Information Systems environment.

Flood Risk Analysis in Potential Points, Zerin City in Erbil as a Case Study

The city of Erbil, the capital of the Kurdistan Region-Iraq, is exposed to frequent floods and cause human and material losses. The current research is analysis of floods as a case study on Zerin City, which was exposed to flood last session 2021-2022. The analysis is based on using different Hydrologic software and digital elevation models, soil data, rainfall data and land use data, were used in order to determine the boundary of catchment area, the area extension of flood plain, depth of flood, water velocity through hydrologic modeling. The results showed that there is a big similarity between the real flood and the modeled flood. Some of the natural water streamlines (valleys) have been filled and the remaining were unable to pass the excess flow generated by the storm. The agricultural lands were not ploughed due to the late rains in this season. Accordingly, increase in the curve number CN (the estimated CN was 79) have been used, the flood inundation, water depth, and velocity through the modeling rainfall storm of return period 50 years on the Zerin City has been done in modeling. The results are a scientific tool that can be used to assess the damages of the study area, and is useful for decision makers.

An Improved Fineness Flood Risk Analysis Method Based on Digital Terrain Acquisition

An Improved Fineness Flood Risk Analysis Method Based on Digital Terrain Acquisition