Examining direct and indirect flood damages in residential and business sectors through an empirical lens.

Investment to reduce flood risk for social and economic wellbeing requires quantitative evidence to guide decisions. Direct and indirect flood damages at individual household and business building levels were assessed in this study using multivariate analysis with three groups of flood damage attributes, i.e., flood characteristics, socioeconomic conditions, and building types. A total of 172 and 45 respondents from residential and commercial buildings were gathered through door-to-door interviews at areas in Peninsular Malaysia that were pre-identified to have frequently flooded. Two main findings can be drawn from this study. First, flood damage is greatly contributed by high-income households and businesses, despite them being less exposed to floods than low-income earners. This supports the current use of mean economic damage in engineering-based flood intervention analysis. Second, indirect damages increase with the increase in family size, indicating the importance of strengthening preparedness and social support to those with great social responsibility. Overall, the study highlights the importance of holistic flood management accounting for both direct and indirect losses.

US tropical cyclone flood risk: Storm surge versus freshwater.

Despite persistent record-breaking flood losses from tropical cyclones (TCs), the United States continues to be inadequately prepared for TC flood events, with the deficiency in residential flood insurance being a prime representation of this. One way to address this is through a better quantification of TC flood risk including variations associated with freshwater versus storm surge flood hazard and damage. We analyze actual residential flood claim data from the National Flood Insurance Program (NFIP) for the full set of all 28 significant US landfalling TC-related flood events from 2001 to 2014 which we split by storm surge and freshwater. We illustrate key differences between the numbers of claims, paid claim amounts, and damage for freshwater and surge claims, as well as evaluate differences associated with flood zone, state, TC event, and flood depth. Despite the typical focus on surge TC flooding, freshwater flooding accounts for over 60% of TC paid claim and damage amounts. Surge flooding often occurs outside of high-velocity flood zones, which is not reflected in the NFIP premiums. Statistical analysis indicates that depth-damage ratios vary significantly by surge versus freshwater and by geography. State-level analysis shows that land-use policies and building codes likely affect differences in damage along with storm characteristics and geography. The findings highlight the need to mitigate and manage both freshwater and surge TC flood risk and for more individualized flood insurance premiums less tied to flood zone. It appears that the latter need may be addressed by the Federal Emergency Management Agency (FEMA)'s Risk Rating 2.0.

Modeling the association between socioeconomic features and risk of flood damage: A local-scale case study in Sri Lanka.

Floods cause severe damage to people as well as to properties. The same flood can cause different levels of damage to different households, but investigations into floods tend to be conducted on regional and national scales, thereby missing these local variations. It is therefore necessary to understand individual experiences of flood damage to implement effective flood management strategies on a local scale. The main objectives of this study were to develop a model that represents the relationship between socioeconomic conditions and flood damage at a local scale, and to understand the socioeconomic factors most closely tied to flood damage. The analysis is novel in that it considers not only the impact of flood characteristics, but also the impact of social, economic, and geographic factors on flood damage. This analysis derives from a quantitative modeling approach based on community responses, with the responses obtained through questionnaire surveys that consider four consecutive floods of differing severity. Path analysis was used to develop a model to represent the relationships between these factors. A randomly selected sample of 150 data points was used for model development, and nine random samples of 150 data points were used to validate the model. Results suggest that poor households, located in vulnerable, low-lying areas near rivers, suffer the most from being exposed to frequent, severe floods. Further, the results show that the socioeconomic factors with the most significant bearing on flood damage are per capita income and geographic location of the household. The results can be represented as a cycle, showing that social, economic, geographic, and flood characteristics are interrelated in ways that influence flood damage. This empirical analysis highlights a need for local-scale flood damage assessments, as offered in this article but seldom seen in other relevant literature. Our assessment was achieved by analyzing the impact of socioeconomic and geographic conditions and considering the relationship between flood characteristics and flood damage.

CityGML urban model generation using national public datasets for flood damage simulations: A case study in Korea.

Managing information at city level has become increasingly important owing to the introduction of smart cities and the increasing severity of disasters due to climate change. A data collection framework, model construction, and information management must be established to systematically manage information at the city level. This study developed an urban model generation method using detailed attributes within the City Geography Markup Language (CityGML), a standard data schema for 3D representation of cities based on different types of publicly available information within Korea. The generated model was used to develop a method for simulating flooding status, degree of flooding, and level of building damage after heavy rainfall, in Korea. Furthermore, we developed a method to estimate the loss of human life and property damage by combining the results of the flood analysis with the city model. The proposed methodology supports the creation of standard-based models for flood analysis and exhibits strong interoperability for application to different areas of analysis.

Emergency Response Using Volunteered Passenger Aircraft Remote Sensing Data: A Case Study on Flood Damage Mapping.

Current satellite remote sensing data still have some inevitable defects, such as a low observing frequency, high cost and dense cloud cover, which limit the rapid response to ground changes and many potential applications. However, passenger aircraft may be an alternative remote sensing platform in emergency response due to the high revisit rate, dense coverage and low cost. This paper introduces a volunteered passenger aircraft remote sensing method (VPARS) for emergency response. It uses the images captured by the passenger volunteers during flight. Based on computer vision algorithms and geocoding procedures, these images can be processed into a mosaic orthoimage for rapid ground disaster mapping. Notable, due to the relatively low flight latitude, small clouds can be easily removed by stacking multi-angle tilt images in the VPARS method. A case study on the 2019 Guangdong flood monitoring validates these advantages. The frequent aircraft revisit time, intensive flight coverage, multi-angle images and low cost of the VPARS make it a potential way to complement traditional remote sensing methods in emergency response.

Effects of spatial planning on future flood risks in urban environments.

Urban development may increase the risk of future floods because of local changes in hydrological conditions and an increase in flood exposure that arises from an increasing population and expanding infrastructure within flood-prone zones. Existing urban land use change models generally consider the expansion process and do not consider the densification of existing urban areas. In this paper, we simulate 24 possible urbanization scenarios in Wallonia region (Belgium) until 2100. These scenarios are generated using an agent-based model that considers urban expansion and densification as well as development restrictions in flood-prone zones. The extents of inundation and water depths for each scenario are determined by the WOLF 2D hydraulic model for steady floods corresponding to return periods of 25, 50, and 100 years. Our results show that future flood damages and their spatial distributions vary remarkably from one urbanization scenario to another. A spatial planning policy oriented towards strict development control in flood-prone zones leads to a substantial mitigation of the increased flood damage. By contrast, a spatial planning policy exclusively oriented to infill development with no development restrictions in flood-prone zones would be the most detrimental in terms of exposure to flood risk. Our study enables the identification of the most sensitive locations for flood damage related to urban development, which can help in the design of more resilient spatial planning strategies and localize zones with high levels of flood risk for each scenario.

The 2011 flood event in the Mekong Delta: preparedness, response, damage and recovery of private households and small businesses.

Floods frequently cause substantial economic and human losses, particularly in developing countries. For the development of sound flood risk management schemes that reduce flood consequences, detailed insights into the different components of the flood risk management cycle, such as preparedness, response, flood impact analyses and recovery, are needed. However, such detailed insights are often lacking: commonly, only (aggregated) data on direct flood damage are available. Other damage categories such as losses owing to the disruption of production processes are usually not considered, resulting in incomplete risk assessments and possibly inappropriate recommendations for risk management. In this paper, data from 858 face-to-face interviews among flood-prone households and small businesses in Can Tho city in the Vietnamese Mekong Delta are presented to gain better insights into the damage caused by the 2011 flood event and its management by households and businesses.

Dataset on the expansion and consolidation of flooded settlements in the Dosso Region, Niger.

Flood risk reduction at the local scale requires knowledge of the settlements which are most exposed to floods, and those where the existing measures are insufficient to handle the threats. The knowledge on spatial dynamics of the flooded human settlements is limited, especially that of the smaller ones, such as the settlements in the sub-Saharan Africa. The dataset on 122 flooded settlements in the Dosso Region (Niger) offers information on: the built-up area and the number of buildings with corrugated iron roofs in 2004, 2012, and 2019 (average dates), the type of human settlements (city, rural town, village, or hamlet), the flood dates and the number of buildings collapsed between 2011 and 2019. The data on the built-up area and the number of buildings with corrugated iron roofs were extracted by visual photointerpretation from very high-resolution images accessible through Google Earth Pro. The information on the settlement category was obtained from the Human Settlements National Directory (French acronym, ReNaLoc) published by the National Institute of Statistics of Niger. The dates of floods and the data on the number of collapsed buildings were obtained from the open access national database on flooding, known by the French acronym, BDINA. These data can be reused to build a geodatabase for flood risk reduction and to draft the municipal and regional development plans. Their potential reuse allows for the identification of settlements undergoing the most rapid physical expansion, built-up area in a flood-prone zone, and settlements that require protection and flood risk reduction policies. Additionally, the dataset can also be used to verify the accuracy of the built-up area obtained from the satellite images with coarse resolution and for comparisons with other regions in Niger and in sub-Saharan Africa.

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.

Exploring trade-offs among the multiple benefits of green-blue-grey infrastructure for urban flood mitigation.

Climate change is presenting one of the main challenges to our planet. In parallel, all regions of the world are projected to urbanise further. Consequently, sustainable development challenges will be increasingly concentrated in cities. A resulting impact is the increment of expected urban flood risk in many areas around the globe. Adaptation to climate change is an opportunity to improve urban conditions through the implementation of green-blue infrastructures, which provide multiple benefits besides flood mitigation. However, this is not an easy task since urban drainage systems are complex structures. This work focuses on a method to analyse the trade-offs when different benefits are pursued in stormwater infrastructure planning. A hydrodynamic model was coupled with an evolutionary optimisation algorithm to evaluate different green-blue-grey measures combinations. This evaluation includes flood mitigation as well as the enhancement of co-benefits. We confirmed optimisation as a helpful decision-making tool to visualise trade-offs among flood management strategies. Our results show that considering co-benefits enhancement as an objective boosts the selection of green-blue infrastructure. However, flood mitigation effectiveness can be diminished when extra benefits are pursued. Finally, we proved that combining green-blue-grey measures is particularly important in urban spaces when several benefits are considered simultaneously.

[Assessment of schistosomiasis transmission risk after flood damage in Wuhan City].

OBJECTIVE: To assess the schistosomiasis transmission risk after flood damage in Wuhan City. METHODS: Schistosomiasis epidemic villages in Wuhan City were selected by using probability proportional to size sampling (PPS). The field investigations of Oncomelania hupensis snails, the activity of people and cattle on marshland, water infectivity of schistosome, reservoir host infection and wild feces contamination were conducted. I-III levels of risk environments were assessed and treated with appropriate measures. RESULTS: A total of 90 schistosomiasis epidemic villages and 170 environments were monitored. Totally 9 811 snails were dissected but no Schistosoma japonicum infected snails were found. There were significant decreases in the density of snails and the survival rate of living snails after the flood (χ2 = 102.517, t = 4.724, both P < 0.01). Totally 289 pieces of wild feces were captured, and no eggs of S. japonicum were detected. A total of 11 surveillance and forecast sites were detected on water systems, and 221 sentinel mice were placed. After breeding, 219 sentinel mice survived (99.10%), and no schistosome infection was detected. In addition, 1 720 mouse traps were placed in 3 survey sites, and 66 Apodemus agrarius were captured, and no schistosome-infected ones were found. All of the environments were assessed as Grade III. Meanwhile, 5 key schistosomiasis control areas were determined, and no emergency happened after the implementation of comprehensive control interventions. CONCLUSIONS: The risk of schistosomiasis transmission remains low in Wuhan City after the flood, but the potential epidemic risk cannot be ignored.

How Flood Damages to Public Infrastructure Affect Municipal Budget Indicators.

Countries' economic activity as well as their fiscal position are vulnerable to climate- and weather related extreme events. Existing research shows that effects on GDP may be either positive or negative, while fiscal implications are clearly negative. Current literature focuses on fiscal implications at the national level. Predicted increases in climate- and weather related extreme events, though, are regionally highly variable. Hence, information concerning the regional vulnerability to specific extreme events is a vital input for adaptation policies. To answer this information demand, this article looks at how flood damages to public infrastructure affect four budget figures (current income balance, asset management balance, financial transaction balance, and the annual result), exploring the case of Upper Austrian municipalities. Based on a dynamic model and a sample of 442 municipalities from 2009 to 2014 it is found that damages to public infrastructure have a negative impact on municipalities' current income balance and their annual result. This indicates a weakening of municipalities' financial situation. To increase municipalities' budgetary resilience with regards to public flood damages, municipalities can revert to stricter land use regulation and precautionary measures such as wet- or dry-flood proofing, or to flood insurance.

[Impact of schistosomiasis transmission by catastrophic flood damage and emergency response in China].

Flood damage is one of the ordinary natural calamities. The areas of middle and down of the Yangtze River and its south are the endemic area of schistosomiasis. As the flood damage, it causes property loss, and harm public and people health severely even. This paper aims at the status of catastrophic flood damage again in the Yangtze River basin, analyzes the impact of schistosomiasis transmission by it, and indicates that at present, the process of schistosomiasis control in China is marching from transmission control to transmission interruption and elimination, but the frequent flooding exacerbates Oncomelania hupensis snail breeding area and schistosomiasis source spreading, which may influence, in a certain extent, the realization of the goal of schistosomiasis control in China. We should timely assess and monitor the impact and risk of schistosomiasis transmission by flood damage, and give the early warning and adopt emergency handling measures in time. This paper also proposes the disaster prevention measures according to flood damage stages (the early, middle, later, and post-flood) and the occurrence and development of damage and endemic situation, so as to control the risk and damage of the disease transmission in a high limit, to consolidate the current achievements of schistosomiasis prevention and control and guarantee the realization of the goal of schistosomiasis interruption and elimination in China on the schedule.

Assessment of schistosomiasis transmission risk after flood damage in Wuhan City / 中国血吸虫病防治杂志

To assess the schistosomiasis transmission risk after flood damage in Wuhan City.Schistosomiasis epidemic villages in Wuhan City were selected by using probability proportional to size sampling (PPS). The field investigations of Oncomelania hupensis snails, the activity of people and cattle on marshland, water infectivity of schistosome, reservoir host infection and wild feces contamination were conducted. I–III levels of risk environments were assessed and treated with appropriate measures.A total of 90 schistosomiasis epidemic villages and 170 environments were monitored. Totally 9 811 snails were dissected but no Schistosoma japonicum infected snails were found. There were significant decreases in the density of snails and the survival rate of living snails after the flood (χ2 = 102.517, t = 4.724, both P < 0.01). Totally 289 pieces of wild feces were captured, and no eggs of S. japonicum were detected. A total of 11 surveillance and forecast sites were detected on water systems, and 221 sentinel mice were placed. After breeding, 219 sentinel mice survived (99.10%), and no schistosome infection was detected. In addition, 1 720 mouse traps were placed in 3 survey sites, and 66 Apodemus agrarius were captured, and no schistosome-infected ones were found. All of the environments were assessed as Grade III. Meanwhile, 5 key schistosomiasis control areas were determined, and no emergency happened after the implementation of comprehensive control interventions.The risk of schistosomiasis transmission remains low in Wuhan City after the flood, but the potential epidemic risk cannot be ignored.

Impact of schistosomiasis transmission by catastrophic flood damage and emergency response in China / 中国血吸虫病防治杂志

Flood damage is one of the ordinary natural calamities. The areas of middle and down of the Yangtze River and its south are the endemic area of schistosomiasis. As the flood damage,it causes property loss,and harm public and people health severely even. This paper aims at the status of catastrophic flood damage again in the Yangtze River basin ,analyzes the impact of schistosomiasis transmission by it,and indicates that at present,the process of schistosomiasis control in China is marching from transmission control to transmission interruption and elimination,but the frequent flooding exacerbates Oncomelania hupen?sis snail breeding area and schistosomiasis source spreading,which may influence,in a certain extent,the realization of the goal of schistosomiasis control in China. We should timely assess and monitor the impact and risk of schistosomiasis transmission by flood damage,and give the early warning and adopt emergency handling measures in time. This paper also proposes the disas?ter prevention measures according to flood damage stages(the early,middle,later,and post?flood)and the occurrence and de?velopment of damage and endemic situation,so as to control the risk and damage of the disease transmission in a high limit,to consolidate the current achievements of schistosomiasis prevention and control and guarantee the realization of the goal of schisto?somiasis interruption and elimination in China on the schedule.