Flood Damage Curves Research Articles

Optimal Design Storm Frequency for Flood Mitigation in the North Valsayn Community of Trinidad

Determining the right amount of money or budget to be spent on flood mitigation works has always been a challenge in developing countries. This study investigates two (2) economic approaches that can be used to determine the level of protection or the optimal design storm frequency for flood mitigation works within the North Valsayn community of Trinidad. The economic approaches investigated can be described as (i) the Cost per Inhabitant (CPI) approach and (ii) the Hydroeconomic Analysis (HEA) approach. To facilitate these economic approaches, the following was done: (i) Identify flood hazards using a calibrated 2D hydraulic model, (ii) Assess the community’s vulnerability by developing a Flood Damage curve, (iii) Identify flood mitigation works for various design storm frequencies, and (iv) Determine the life cycle cost for implementing the design various design solutions. Although both methods are acceptably used in the industry, the study shows a disparity in defining a project’s budget and the Optimal Design Storm Frequency that is worth paying attention to by decision and policy makers, government agencies, practicing engineers, project managers and other stakeholders although both are acceptably used in the industry.

Application and Validation of Flood Damage Curves for Wastewater Treatment Facilities (WWTF), Case Examples in Rhode Island

The STORMTOOLS Coastal Environmental Risk Index (CERI) has historically been used to assess the damage to residential and commercial structures from coastal flooding, including the effects of sea level rise (SLR) in RI. In the present study, CERI was extended to address the impact of flooding for 100 yr storm, including the effects of SLR, to the newly renovated Warren, RI wastewater treatment facilities (WWTF), located on the tidal Warren River, using FEMA HAZUS damage curves. The analysis shows that the average damage for 100 yr flooding, across all components of the facility, increases with sea level from 16% (0 ft SLR), 23% (2 ft SLR), 26% (3 ft SLR), to 28% (5 ft SLR). The primary settling and chlorination tanks are at most risk and the aeration and reaction tanks at least risk. In an effort to validate the FEMA HAZUS WWTF damage curves, CERI was applied to predict flood damage during the 3 day, March/April 2010 flooding event (500 yr) to the Cranston, Warwick, and West Warwick WWTF located on the Pawtuxet River, RI. The predictions of the damage to each WWTF from this event were compared to observations of the damage made by the plant operators. The percent damage was estimated by comparing the cost of the damage to the assessed value of the facility. Using the FEMA HAZUS damage curves for the observed level of inundation (7 to 8 ft) predicted that the Warwick and West Warwick facility damage ranged from 15 to 45% with an average value of about 30%. The Cranston WWTF damage was very low (<1%) because of the elevation of the facility. The observed damage for the 2010 flood event was approximately 21% for the Warwick facility and 18% for the West Warwick facility, between the FEMA HAZUS lower and average values. Damage to the Cranston facility was consistent between FEMA HAZUS and observed values at <1%.

The role of socio-economic and property variables in the establishment of flood depth-damage curve for the data-scarce area in Malaysia

ABSTRACT Flood is a frequent natural hazard worldwide that has significant financial consequences. Physical damages caused by floods are commonly estimated by stage-damage functions. However, these methods usually consider only the water depth and the type of buildings at risk. This study uses the empirical dataset collected from 2013 flood in the Kuantan River Basin to explore the influence of impact and resistance variables on the level of flood damages using the tree-based Random Forest approach. Due to data scarcity, the multivariate flood damage model has been utilized to establish the flood damage curves in the study area. As the result, in addition to flood depth, flood damage is also influenced by flood duration, value of properties, types of properties and business/household income. The obtained flood depth–damage curves are sufficient and comparable with other studies, with the R 2 of more than 0.80 for both residential and commercial categories.

Urban flood event and associated damage in the Benue valley, Nigeria

Flooding events in the Lower Benue valley of Nigeria are often associated with huge damage to properties and loss of life in the adjoining communities. Specific objectives of this study were to (i) examine the characteristics of rainfall and discharge at the major river in the study area—Benue trough of Nigeria; (ii) assess the occurrence of extreme rainfall conditions and other flood-triggering/exacerbating factors; and (iii) determine flood damage extent and available warning system in the area. Specific reference was made to the 2017 flood event in the area. Method used was an integrated environmental approach that combines analysis of rainfall and discharge data with social surveys, remote sensing and geographical information system. Standardized Precipitation Index (SPI), Precipitation Concentration Index (PCI) as well as flood damage curves were analysed with land use/cover change and soil data to establish the nature of the flood and its impacts. Result showed that rainfall has increased in the study area in October–December and February (b ≤ 0.13) but has decreased in the other months, albeit insignificantly (R2 < 0.5). Rainfall–runoff relationship at the gauge station was weak (b = 16.67, R2 = 0.21), and indicates the influence of antecedent soil moisture content at the gauge station, while the well-drained nature of the soil, its sedimentary geology and land use/cover analysis would indicate the dominance of infiltration-excess flow. The results of the SPI and PCI, which categorized the study area as largely wet during the study period (13.5% of the years classified as extremely wet and 54.1% wet), as well as high record of consecutive rain days revealed the vulnerability of the area to flood hazards in the wet months. Eighty-five per cent of the vulnerable residents are considerably poor, earning an equivalent of US $4.3 daily, and live in non-reinforced concrete masonry (64%) and wooden buildings (24%). The study recommends extensive flood control policy for the area and similar flood-prone communities.

Assessment and mitigation of tangible flood damages driven by climate change in a tropical city: Hat Yai Municipality, southern Thailand

Climate change-induced floods in tropical urban areas have presented a serious global challenge because of failed conventional stormwater management practices. This research aims to develop a comprehensive methodological framework for flood damage estimation and mitigation, particularly in a tropical urban city. In this study, interdisciplinary fields were integrated through statistical downscaling, hydrologic-hydraulic modeling, and the development of flood damage curves. Relationships between tangible flood damage and flood-borne outbreak with flood depths were elucidated to predict future damage. Various flood mitigation strategies were evaluated. Herein, Hat Yai Municipality in Southern Thailand was selected as the study area. The flood simulation was conducted for 2010 and the highest flood damage sensitivity was exhibited by non-commercial buildings due to significant commercial stock damage, which was followed by that observed for detached houses. There was a strong linear relationship between the number of patients infected with leptospirosis and flood depth (R2 = 0.85). For climate change studies, flood maps for storms with 20-, 50-, and 100-year return periods under the A2/RCP8.5 scenario were generated using hydrological-hydraulic 1D/2D model; these maps were applied with the developed flood damage curves for damage estimation. It was found that reducing flood damage by implementing agroforestry and expanding the main bypass channel provides comparable damage reductions of −25.5% and − 27.5%, respectively, under the worst-case scenario of a 100-year return period in 2040–2059. Therefore, to deal with uncertain climate change situations, the incorporation of structural and non-structural measures is recommended. Such a combination when coupled with an eight-hour flood awareness time can result in a damage reduction of −59.9%. A flood warning system was in high demand by residents in the area; however, damage reduction from this measure alone was not high (approximately −17.0%) when compared to that obtained with other measures; consequently, additional measures were needed.

The determination of flood damage curve in areas lacking disaster data based on the optimization principle of variation coefficient and beta distribution

Flood loss assessment is an important part of urban flood risk management, and the establishment of disaster damage curve is the key of loss assessment. Because of the limitation of data, it is difficult for cities lacking disaster data to fit the damage curve through historical data. Generally, transferring the damage curve among regions is an effective method, but there are problems of data reference and statistical uncertainty. In view of the inland plain cities lacking disaster data, the damage factor of the data reference area can be transferred to the study area by referring to the principle of analogy. Then, based on the optimization principle of the minimum variation coefficient and the maximum beta distribution probability, the citation error and statistical error in the damage factor quotation were reduced, and the relatively accurate damage factor in the study area was obtained, and then the water depth - damage factor curve was established. Thus, a generalized damage curve fitting method for cities lacking disaster data was formed, which took the regional index values as the input parameters and the damage curves as the output results. Finally, taking Zhengzhou City, China as the study area, the loss curves of 10 property types were calculated. Compared with the original data, the average variation coefficient of the optimal scheme set was reduced by 0.1; the probability of the optimal value was increased by 1.39% compared with the average value. In addition, the method test was conducted in Jinan, China, where the data were available, and it was found that the three types of errors were significantly lower than the traditional comparison method of single city as reference object. This study is expected to provide a scientific reference for the establishment of flood damage curve in cities or areas lacking disaster data.

Semi-probabilistic coastal flood impact analysis: From deterministic hazards to multi-damage model impacts

Coastal flood impact assessments are important tools for risk management and are performed by combining the hazard component with the vulnerability of exposed assets, to quantify consequences (or impacts) in terms of relative or absolute (e.g. financial) damage. The process generates uncertainties that should be taken into account for the correct representation of the consequences of floods. This study presents a coastal flood impact application at the spatial level of the Stavanger municipality (Norway), based on a multi-damage model approach able to represent impacts, and their overall uncertainty. Hazard modelling was performed using the LISFLOOD-FP code, taking into account historical extreme water level events (1988–2017) and relative sea level rise scenarios. Direct impacts were calculated in the form of relative and financial damage for different building categories, using flood damage curves. The results showed that the expected impacts are fewer than 50 flooded receptors and less than €1 million in damage in the current sea level scenario. The impacts could double by the end of the century, considering the most optimistic relative sea level scenario. The results were discussed considering the limitations of the approach for both hazard and impact modelling, that will be improved in future implementations. The outcome of this study may be useful for cost–benefit analyses of mitigation actions and local-scale plans for adaptation.

Quantitative assessment of flood risk with evaluation of the effectiveness of dam operation for flood control: A case of the Bago River Basin of Myanmar

Because property damage and loss of life owing to floods have increased in many countries in recent years, accurate assessment of flood risk is urgently needed for effective flood management. Improving the assessment of flood risk requires considering the impact of dam operation for flood control because dams and reservoirs play important roles in the assessment of flood hazards and associated damage. However, the impact of dam operation on flood hazards and associated damage was not considered well in previous assessments of flood risk. This paper focused on the quantitative assessment of flood hazard and risk, including the effectiveness of dam operation for flood prevention. The grid-based approach integrating the following was applied for analysis: (i) a hydrological–hydraulic model, (ii) a method considering the dam operation for flood control, and (iii) an assessment of flood damage. To assess the risk, flood characteristics were computed using the rainfall–runoff–inundation hydrological–hydraulic model, and flood damage was estimated by integrating the flood characteristics, flood damage curves, exposure characteristics, and property values. The risk was assessed by focusing on flood damage to residential buildings and assets and agricultural sectors for the largest recent floods and flood events with different return periods. This study considered the Bago River Basin of Myanmar. Results show that the dam operation for flood control in the study area reduces the flood inundation area by approximately 10% and flood damage to buildings, assets, and agriculture by approximately 40%, 60%, and 10%, respectively.

Challenges for flood risk management in flood‐prone Sirajganj region of Bangladesh

Although Bangladesh has suffered from different types of floods which have caused enormous damage to properties and lives, managing floods still remains a challenging task. Flood management is a multisectoral activity due to its complexity, scale, and multidisciplinary nature. Sirajganj district can be regarded as one of the most vulnerable areas in Bangladesh and hence a study was carried out for Sirajganj district to provide guidelines to combat challenges to flood risk management. The flood frequency analyses at three river stations using water level data were carried out, the flood inundation map for different return periods and a flood depth versus damage curve are plotted to address the vulnerable areas and damages, and to help design flood mitigation structures. It can be inferred that damages will be proportional to return period since the risk is a function of hazard, vulnerability, and exposure. Both structural and non‐structural measures including rejuvenation of the Jamuna River and low‐cost flood resistant building approaches for flood affected char (island) people are suggested along with a few recommendations to mitigate floods in the study area. The government, Non governmental organization (NGO), funding agencies, and transboundary countries should come forward to mitigate flood hazards to improve the livelihood of the affected people.

The Damage Assessment of Flood Risk Transfer Effect on Surrounding Areas Arising from the Land Development in Tainan, Taiwan

The development with filling method might increase the flood risk and damage in the surrounding areas, especially in low-lying areas. The objective of this study was to develop a methodology to assess the damage of flood risk transfer effect on surrounding areas. We studied a development located in Tainan, Taiwan and applied a SOBEK model to analyze the transfer effect of flood risk, and calculated the amount of loss in the surrounding land. After land development, the risk of flooding in the development zone declined. However, the risk of flooding in the southern area of the development zone increased. The development of land changed the original decentralized drainage system to centralized drainage system. The peak outflow discharge of surface runoff increased so much that it was more than the flow capacity of the downstream channel. This resulted in transferring the flood risk to the surrounding areas. Direct losses due to floods for industrial, commercial, residential, and agricultural lands as well as public facilities were calculated by the flood damage curves. Indirect losses were estimated using the industry-related model. The expected annual damages before and after land development in the southern area of the development zone were NT$ 6.38 million and NT$ 7.39 million, showing that the expected annual damage was increased by NT$ 1.01 million after land development.

FLOOD RISK ASSESSMENT: A REVIEW OF FLOOD DAMAGE ESTIMATION MODEL FOR MALAYSIA

Flood damage assessment is important in flood risk management for the assessment of flood vulnerability, development of flood risk map and flood management financial appraisal. In Malaysia, there is a lack of studies on flood damages estimation. In addition, the needed data for the assessment of flood damages is scarce. This review identified the approaches and problems in flood damage assessment. For Malaysia, the combination of four elements namely; flood characteristics (flood depth and flood duration), characteristic of exposed elements, value of exposed element and flood damage function curve are recommended. The scarcity of data for developing flood damage curve could partly be overcome by applying synthetic method to generate additional data from the existing flood damage data.

Estimation of river flood damages in Jakarta, Indonesia

Flooding is a serious problem in Jakarta, and detailed estimation of flood damage is necessary to design optimal flood management strategies. This study aims to estimate flood damage in a densely populated area in Jakarta by means of a survey, to develop the relationship between flood characteristics and flood damage, and to compare the damage estimates from the survey with the damage estimates obtained by a flood damage model for Jakarta, i.e. the damage scanner model. We collected data on economic losses of the January 2013 flood in a survey of flood-affected households and business units in Pesanggrahan River. The actual flood damage in the survey area is US$ 0.5 million for the residential sector and US$ 0.7 million for the business sector. The flood damage for a similar event in the same area based on the damage scanner model is estimated to be US$ 1.3 million for the residential sector and US$ 9.2 million for the business sector. The flood damage estimates obtained by the survey approach are lower compared to the damage scanner approach due to different ways in obtaining flood damage data and in defining the maximum flood damage per object, the different spatial levels of analysis, and uncertainties in constructing the flood damage curves that were applied in the damage scanner model.

A Framework for Flood Risk Analysis and Benefit Assessment of Flood Control Measures in Urban Areas.

Flood risk analysis is more complex in urban areas than that in rural areas because of their closely packed buildings, different kinds of land uses, and large number of flood control works and drainage systems. The purpose of this paper is to propose a practical framework for flood risk analysis and benefit assessment of flood control measures in urban areas. Based on the concept of disaster risk triangle (hazard, vulnerability and exposure), a comprehensive analysis method and a general procedure were proposed for urban flood risk analysis. Urban Flood Simulation Model (UFSM) and Urban Flood Damage Assessment Model (UFDAM) were integrated to estimate the flood risk in the Pudong flood protection area (Shanghai, China). S-shaped functions were adopted to represent flood return period and damage (R-D) curves. The study results show that flood control works could significantly reduce the flood risk within the 66-year flood return period and the flood risk was reduced by 15.59%. However, the flood risk was only reduced by 7.06% when the flood return period exceeded 66-years. Hence, it is difficult to meet the increasing demands for flood control solely relying on structural measures. The R-D function is suitable to describe the changes of flood control capacity. This frame work can assess the flood risk reduction due to flood control measures, and provide crucial information for strategy development and planning adaptation.

Flood damage curves: new insights from the 2010 flood in Veneto, Italy

AbstractFlood damage modelling is becoming an essential component in flood risk management. However damage assessments are affected by large uncertainty, mainly related to the use of depth–damage functions. In some countries, where no site‐specific curves are available, a transfer of damage models developed from other areas is required, adding extra uncertainty in the modelling process. This paper discusses the transferability in space of damage curves from literature, with a focus on ‘function uncertainty’, pointing out, especially for mesoscale ones, the lack of detailed information in terms of flood and/or building characteristics that can allow to identify the conditions of applicability of the models. New site‐specific depth–damage functions are then developed for the residential sector, at meso‐ and microscale, based on damage data from the 2010 flood in Veneto, Italy. The application of the new curves reveals a better performance of the mesoscale model compared with the more detailed microscale one, probably due to the small extent of the inundated area.

내수침수시나리오와 침수피해곡선을 활용한 도시지역 내수침수피해특성 분석

최근 우리나라에서는 기후변화에 의한 집중호우의 영향으로 여름철마다 내배수 시설물의 설계빈도를 벗어나는 강우사상이 빈번하게 발생하고 있다. 특히 불투수성이 큰 도시지역의 경우에는 우수관거 및 펌프장에 대한 의존도가 높아 극치강우로 인한 내수침수의 발생 및 그 피해가 증가하고 있다. 본 연구에서는 내수침수 위험도가 높은 지역의 내수침수피해 특성을 분석할 수 있는 방법을 제시하였다. 부산시 연제구 거제지구를 대상으로 다양한 지속시간과 강우강도를 고려한 강우시나리오를 구축하였으며, XP-SWMM을 활용하여 내수침수시나리오를 구축하였다. 본 연구에서는 다차원법을 바탕으로 만들어진 내수침수피해액 산정법을 활용하여, 침수심과 침수면적에 따른 침수피해액을 산정한 후, 내수침수시나리오에 따른 침수피해곡선을 작성하였다. 또한 이를 바탕으로 대상지역의 내수침수피해 특성을 분석하였다. 본 연구를 통하여 침수가 발생하기 시작하는 강우량 및 큰 침수피해를 유발하는 호우사상을 파악하며, 침수가 발생되는 지역의 침수면적, 침수심, 침수피해액을 예측하는 수단으로 활용할 수 있을 것이다. Recently, in Korea, localized heavy rainfall events have occurred frequently due to climate change. Especially, since urban areas depend heavily on pump and pipe systems, extreme rainfalls that exceed the design capacity of drainage facility result in increasing inland flood damage. This study proposed a methodology to analyze urban flood damage characteristics in inland flood prone areas. After firstly constructing rainfall scenarios which have various durations and intensities, inland flood scenarios were developed using XP-SWMM. This study presented the inland flood damage analysis (IFDA) to calculate inland flood damage from the inland flood scenarios. Based on the inland flood scenarios and corresponding flood damage curves, the characteristics of damage due to inland flood were analyzed using the relationships among precipitation depth, flood depth, and flood area. The proposed method can be used to identify the storm event resulting in heavy flood damage, and to predict the flood area, depth and damage from various storm events.

Low‐Probability Flood Risk Modeling for New York City

The devastating impact by Hurricane Sandy (2012) again showed New York City (NYC) is one of the most vulnerable cities to coastal flooding around the globe. The low-lying areas in NYC can be flooded by nor'easter storms and North Atlantic hurricanes. The few studies that have estimated potential flood damage for NYC base their damage estimates on only a single, or a few, possible flood events. The objective of this study is to assess the full distribution of hurricane flood risk in NYC. This is done by calculating potential flood damage with a flood damage model that uses many possible storms and surge heights as input. These storms are representative for the low-probability/high-impact flood hazard faced by the city. Exceedance probability-loss curves are constructed under different assumptions about the severity of flood damage. The estimated flood damage to buildings for NYC is between US$59 and 129 millions/year. The damage caused by a 1/100-year storm surge is within a range of US$2 bn-5 bn, while this is between US$5 bn and 11 bn for a 1/500-year storm surge. An analysis of flood risk in each of the five boroughs of NYC finds that Brooklyn and Queens are the most vulnerable to flooding. This study examines several uncertainties in the various steps of the risk analysis, which resulted in variations in flood damage estimations. These uncertainties include: the interpolation of flood depths; the use of different flood damage curves; and the influence of the spectra of characteristics of the simulated hurricanes.

Estimation of an absolute flood damage curve based on an Austrian case study under a dam breach scenario

Abstract. To date, in Austria no empirical assessment of absolute damage curves has been realized on the basis of detailed information on flooded buildings due to a dam breach, presumably because of the lack of data. This paper tries to fill this gap by estimating an absolute flood-damage curve, based on data of a recent flood event in Austria in 2006. First, a concise analysis of the case study area is conducted, i.e., the maximum damage potential is identified by using raster-based GIS. Thereafter, previous literature findings on existing flood-damage functions are considered in order to determine a volume-water damage function that can be used for further flood damage assessment. Finally, the flood damage function is cross validated and applied in prediction of damage potential in the study area. For future development of the estimated flood damage curve, and to aid more general use, we propose verification against field data on damage caused by natural waves in rivers.

The assessment of damage caused by floods in the Brazilian context

The present paper describes theoretical aspects and the main results on the development of a methodology for the global evaluation of direct damage caused by floods. This methodology is based on the use of standard flood damage curves versus depth of inundation on dwelling, commerce and service sectors. The research was developed based on field surveys in the city of Itajubá, located in the valley of the Sapucaí River, in Minas Gerais state in the southeast region of Brazil. In January 2000, this city suffered severe floods where more of 70% of the urban area was affected; with depths of inundation higher than 3 m in certain areas. The empirical data were obtained through questionnaires applied in the ravaged area in 2002. The questionnaires allowed the characterization of the dwellings and their content, as well as the different categories on commercial and service activities. The generic curves obtained from the data in the survey were used at the same site to evaluate the amount of potential flood damage in relation to different hydrologic risks.

Flood-damage curves: Methodological development for the Brazilian context

Flood-damage curves: Methodological development for the Brazilian context

Flood-damage curves: Methodological development for the Brazilian context

The present paper describes the main results of an on-going research aiming to develop standard flood damage data in the form of generic flood-damage curves. This type of curve allows estimating flood damages from the depth of inundation. Although the research project encompasses flood damages on different urban land use activities (residential, commercial, services and industrial land uses), the paper focus on residential flood damage information. The empirical data used on this research was obtained from systematic surveys performed in the city of Itajubá, a town with 85.000 inhabitants located in the Sapucaí river valley in the South-eastern region of Brazil, during the year of 2002. The survey consisted in interviewing residents in the Itajubá flood prone urban area in order to develop a data base characterizing the social class, the building fabric, the contents (inventory items) and the damages caused to dwellings by a reference flood event, the 2000 flood event. During this event, the town had more than 70% of its urban area flooded for three days and, in some densely urbanised areas, the depth of water was superior to three meters. The FDC curves obtained show relatively high damage according to the submersion depth considering the Brazilian context. This issue suggests that inhabitants can rarely recover, in the short time, from all the harm caused by flooding.