High Flood Risk Research Articles

Application of a Novel Hybrid Method for Flood Susceptibility Mapping with Satellite Images: A Case Study of Seoul, Korea

This paper proposes a novel hybrid method for flood susceptibility mapping using a geographic information system (ArcGIS) and satellite images based on the analytical hierarchy process (AHP). Here, the following nine multisource environmental controlling factors influencing flood susceptibility were considered for relative weight estimation in AHP: elevation, land use, slope, topographic wetness index, curvature, river distance, flow accumulation, drainage density, and rainfall. The weight for each factor was determined from AHP and analyzed to investigate critical regions that are more vulnerable to floods using the overlay weighted sum technique to integrate the nine layers. As a case study, the ArcGIS-based framework was applied in Seoul to obtain a flood susceptibility map, which was categorized into six regions (very high risk, high risk, medium risk, low risk, very low risk, and out of risk). Finally, the flood map was verified using real flood maps from the previous five years to test the model’s effectiveness. The flood map indicated that 40% of the area shows high flood risk and thus requires urgent attention, which was confirmed by the validation results. Planners and regulatory bodies can use flood maps to control and mitigate flood incidents along rivers. Even though the methodology used in this study is simple, it has a high level of accuracy and can be applied for flood mapping in most regions where the required datasets are available. This is the first study to apply high-resolution basic maps (12.5 m) to extract the nine controlling factors using only satellite images and ArcGIS to produce a suitable flood map in Seoul for better management in the near future.

Deoxynivalenol Occurrence in Triticale Crops in Romania during the 2012-2014 Period with Extreme Weather Events.

This article aims to evaluate deoxynivalenol occurrence in triticale crops in Romania in years with extreme weather events (2012: Siberian anticyclone with cold waves and heavy snowfall; 2013 and 2014: “Vb” cyclones with heavy precipitation and floods in spring). The deoxynivalenol level in triticale samples (N = 236) was quantified by ELISA. In Romania, the extreme weather events favoured deoxynivalenol occurrence in triticale in Transylvania and the Southern Hilly Area (44–47° N, 22–25° E) with a humid/balanced-humid temperate continental climate, luvisols and high/very high risk of floods. Maximum deoxynivalenol contamination was lower in the other regions, although heavy precipitation in May–July 2014 was higher, with chernozems having higher aridity. Multivariate analysis of the factors influencing deoxynivalenol occurrence in triticale showed at least a significant correlation for all components of variation source (agricultural year, agricultural region, average of deoxynivalenol, average air temperature, cumulative precipitation, soil moisture reserve, aridity indices) (p-value < 0.05). The spatial and geographic distribution of deoxynivalenol in cereals in the countries affected by the 2012–2014 extreme weather events revealed a higher contamination in Central Europe compared to southeastern and eastern Europe. Deoxynivalenol occurrence in cereals was favoured by local and regional agroclimatic factors and was amplified by extreme weather events.

Remote sensing and GIS for urbanization and flood risk assessment in Phnom Penh, Cambodia

This study performed flood risk assessment in urbanized areas using geospatial and remotely sensed data for 1990–2005–2020 periods using the linear unmixing model (LUM), random forests (RF), and support vector machines (SVM). The urban mapping results verified with reference data indicated close agreement, with the overall accuracies and Kappa coefficients higher than 88.9% and 0.78, respectively. A remarkable increase of 14.9% in urban area was observed for the period 2005–2020, compared to 7.2% during the period 1990–2005. The results of flood risk modeling revealed that RF produced slightly more accurate results than SVM. The flood risk areas aggregated with urban maps showed that the larger urban flood risk area was especially observed for the period 2005–2020. The urban areas of high/very high and medium flood risks calculated for 2020 were 19.7% and 20%, respectively. Such flood risk areas were also overlaid with the population density for urban planning and management.

Assessing road network resilience: An accessibility comparative analysis

In this study, we measure the resilience of the road networks in two Mediterranean regions: Valencia (Spain) and Sardinia (Italy). We apply a framework that is able to monitor the deterioration in territorial accessibility of the two systems in response to the cumulative elimination of sections. Road sections are removed according to different elimination types: random order, deterministic order of criticality, and deterministic order in areas at high risk of flooding. The results show that the Sardinian network is more resilient than the Valencian network, despite its poorer quality. We demonstrate that the framework can integrate climate change considerations in the resilience assessment. As the framework identifies the most critical sections, the method can be adopted as a support system by transport planners and policy makers.

DISASTER MITIGATION AS AN EFFORT TO MINIMIZE THE IMPACT OF FLOODS IN LAMONGAN DISTRICT

Flood is one of the most dominant disasters in Indonesia with an incident that tends to increase. Lamongan District is an area with a fairly high risk of flooding due to the intensity of which it occurs every year. The high risk of flooding is caused by two reasons, the Bengawan Solo flow and the rainfall (the Bengawan Njero flow). Every flood disaster that occurs will certainly cause various impacts from damage to infrastructure, loss of property, and casualties. Disaster management efforts are certainly carried out to minimize the risk and impact of flood disasters in Lamongan District, such as through disaster mitigation. This research aims to determine disaster mitigation carried out in Lamongan District as an effort to minimize the impact of flooding. This research used descriptive qualitative research methods. Disaster mitigation in this research is divided into two according to Perka BNPB Number 4 of 2008, active disaster mitigation and passive disaster mitigation. The results of this research indicated that active mitigation in Lamongan District was carried out through, making flood disaster signs, supervising spatial planning, conducting training and counseling on flood disasters to officials, communities, and students, planning evacuation places and flood disaster evacuation routes and making embankment reinforcement. Meanwhile, passive mitigation in Lamongan District was carried out through, drafting laws and regulations, making flood-prone maps, making guidelines for every disaster management activity, making disaster posters, conducting flood risk studies, conducting disaster education, forming village forums, and prioritizing disaster management in development planning.

Peatland subsidence enhances cultivated lowland flood risk

Peatlands worldwide are being threatened by intensive land use and drainage, which leads to soil subsidence. This has consequences for farming, especially on low-gradient cultivated peat-dominated lowlands with high flood risk. In this study, we combined historical soil elevation data and new lidar data to improve the estimation of subsidence and its consequences for lowland river systems. The results showed 202−349 mm subsidence within the last 24–51 years, with a mean rate of 5.15–9.47 mm y−1 for riparian peatland on the west coast of Finland. The subsidence rate was partly explained by the depth of the organic soil layer (R2 = 0.710, p > 0.05). The results also showed that increasing flooding of cultivated fields is mainly due to soil subsidence, not to increased flooding occurrence in river systems. The area flooded annually was found to increase by 101–194 % for the last 24–51 years, due to soil subsidence near rivers. Generalization of the results to catchment scale indicated an increase in the annual flood zone of 45 % in cultivated fields in one of two study catchments (Siikajoki river basin). These results demonstrate the value of using historical data to study soil subsidence and confirm that the risk of flooding increases in cultivated organic lowlands due to intensive drainage and subsidence. New management strategies, such as peatland rewetting, restoration, and paludiculture, should be considered in future land use plans to reduce subsidence and provide new income streams for farmers.

Applicability of a nationwide flood forecasting system for Typhoon Hagibis 2019

Floods can be devastating in densely populated regions along rivers, so attaining a longer forecast lead time with high accuracy is essential for protecting people and property. Although many techniques are used to forecast floods, sufficient validation of the use of a forecast system for operational alert purposes is lacking. In this study, we validated the flooding locations and times of dike breaking that had occurred during Typhoon Hagibis, which caused severe flooding in Japan in 2019. To achieve the goal of the study, we combined a hydrodynamic model with statistical analysis under forcing by a 39-h prediction of the Japan Meteorological Agency's Meso-scale model Grid Point Value (MSM-GPV) and obtained dike-break times for all flooded locations for validation. The results showed that this method was accurate in predicting floods at 130 locations, approximately 91.6% of the total of 142 flooded locations, with a lead time of approximately 32.75 h. In terms of precision, these successfully predicted locations accounted for 24.0% of the total of 542 locations under a flood warning, and on average, the predicted flood time was approximately 8.53 h earlier than a given dike-break time. More warnings were issued for major rivers with severe flooding, indicating that the system is sensitive to extreme flood events and can issue warnings for rivers subject to high risk of flooding.

Behaviour and performance of a dynamic cobble berm revetment during a spring tidal cycle in North Cove, Washington State, USA

In many places, sandy coastlines and their associated assets are at high risk of erosion and flooding, with this risk increasing under climate change and sea level rise. In this context, dynamic cobble berm revetments represent a potentially sustainable protection technique to armour sandy beaches, reduce wave runup and protect the hinterland against wave attack. However, the behaviour and performance of such structures is not well understood. The dynamic cobble berm revetment located in North Cove, WA, USA, was monitored over a spring tidal cycle in January 2019. A representative 60 m alongshore section was monitored over 10 days using 2D laser scanner (lidar) measurements, GPS ground elevation surveys, Radio Frequency Identification of individual cobbles and revetment thickness measurements. These data were used together to assess the dynamic behaviour and functionality of the revetment throughout the experiment. Over the course of the experiment, the surface elevation changed by up to ±0.5 m, and the revetment volume reduced by an average 0.67 m3/m. These changes were found to be caused by relatively large significant wave height and high water levels. The revetment demonstrated a dynamic stability and the capacity to quickly reshape under changing hydrodynamic conditions. The instrumented cobbles were transported along and cross-shore and accumulated at the toe of the revetment, but were never transported seaward of the toe. The revetment also managed to recover some of the lost volume under moderate wave conditions. The revetment behaviour was found to be influenced by variation in the cobble-sand matrix. The underlying sand dynamics – i.e., accumulation or removal of sand within the cobbles – were found to govern the overall volume changes and were important to the overall stability of the revetment. Seven possible transport regimes were identified, and a model of the internal sand dynamics was developed. During the spring tidal cycle measured here, the revetment protected the sand scarp immediately landward and prevented flooding of the hinterland, while armouring the underlying sand. Over time, renourishment will likely be required due to longshore sediment transport, and preliminary guidelines for this and other aspects of design are suggested.

A Geomorphic Approach for Identifying Flash Flood Potential Areas in the East Rapti River Basin of Nepal

Basin geomorphology is a complete system of landforms and topographic features that play a crucial role in the basin-scale flood risk evaluation. Nepal is a country characterized by several rivers and under the influence of frequent floods. Therefore, identifying flood risk areas is of paramount importance. The East Rapti River, a tributary of the Ganga River, is one of the flood-affected basins, where two major cities are located, making it crucial to assess and mitigate flood risk in this river basin. A morphometric calculation was made based on the Shuttle Radar Topographic Mission (SRTM) 30-m Digital Elevation Model (DEM) in the Geographic Information System (GIS) environment. The watershed, covering 3037.29 km2 of the area has 14 sub-basins (named as basin A up to N), where twenty morphometric parameters were used to identify flash flood potential sub-basins. The resulting flash flood potential maps were categorized into five classes ranging from very low to very high-risk. The result shows that the drainage density, topographic relief, and rainfall intensity have mainly contributed to flash floods in the study area. Hence, flood risk was analyzed pixel-wise based on slope, drainage density, and precipitation. Existing landcover types extracted from the potential risk area indicated that flash flood is more frequent along the major Tribhuvan Rajpath highway. The landcover data shows that human activities are highly concentrated along the west (Eastern part of Bharatpur) and the east (Hetauda) sections. The study concludes that the high human concentrated sub-basin “B” has been categorized as a high flood risk sub-basin; hence, a flood-resilient city planning should be prioritized in the basin.

Dueling emergencies: Flood evacuation ridesharing during the COVID-19 pandemic

Volunteered sharing of resources is often observed in response to disaster events. During evacuations the sharing of resources and vehicles is a crucial mechanism for expanding critical capacity and enabling inclusive disaster response. This paper examines the complexity of rideshare decision-making in the wake of simultaneous emergencies. Specifically, the need for physical distancing measures during the coronavirus (COVID-19) pandemic complicates face-to-face resource sharing between strangers. The ability of on-demand ridesharing to provide emergency transportation to individuals without access to alternatives calls for an understanding of how evacuees weigh risks of contagion against benefits of spontaneous resource sharing. In this research, we examine both sociodemographic and situational factors that contribute to a willingness to share flood evacuation rides with strangers during the COVID-19 pandemic. We hypothesize that the willingness to share is significantly correlated with traditional emergency resource sharing motivations and current COVID-19 risk factors. To test these hypotheses, we distributed an online survey during the pandemic surge in July 2020 to 600 individuals in three midwestern and three southern states in the United States with high risk of flooding. We estimate a random parameter multinomial logit model to determine the willingness to share a ride as a driver or passenger. Our findings show that willingness to share evacuation rides is associated with individual sociodemographics (such as being female, under 36 years old, Black, or republican-identifying) and the social environment (such as households with children, social network proximity, and neighborly sharing attitudes). Moreover, our findings suggest higher levels of income, COVID-19 threat perception, evacuation fear, and household preparedness all correspond with a lower willingness to share rides. We discuss the broader implications of emergency on-demand mobility during concurrent disasters to formulate strategies for transportation agencies and on-demand ridehailing providers.

From Changing Environment to Changing Extremes: Exploring the Future Streamflow and Associated Uncertainties Through Integrated Modelling System

Climate and land-use changes can alter the dynamics of hydro-climatic extremes by modifying the flow regimes. Here, we have attempted to disentangle the relationship between changing environmental conditions and hydro-climatic extremes considering associated uncertainties for the Subarnarekha, a flood prone-basin of India. A comprehensive, integrated modelling system was developed that incorporates a spatially explicit land-use model, a hydrological model, and an ensemble of regional climate models (RCMs). MIKE SHE/MIKE HYDRO RIVER was used to simulate the hydrological processes. The uncertainties associated with model parameters, model inputs, and model structures are analysed collectively using ‘quantile regression.’ A transferable framework was developed for the analysis of hydro-climatic extremes that deal with numerous aspects like sensitivity, occurrences, severity, and persistence for four-time horizons: baseline (1976–2005) and early (2020s), mid (2050s), end-centuries (2080s). ANOVA is used for partitioning uncertainty due to different sources. The results obtained from numerous analysis of the developed framework suggests that low, high, and medium flows will probably increase in the future (20%-85% increase), indicating a higher risk of floods, especially in the 2050s and 2080s. Partitioning of uncertainty suggests RCMs contribute 40%-62% to the uncertainty in streamflow projections. The developed modelling systems incorporates a flexible framework so update any other water sustainability issue in the future. These findings will help better meet the challenges associated with the possible risk of increasing high flows in the future by ceding references to the decision-makers for framing better prevention measures associated with land-use and climate changes.

Assessment of flood risk reduction in DKI Jakarta: Cengkareng Sub-district

Due to geographical condition, Cengkareng is one of a well-known flood-prone area in West Jakarta, Indonesia Annual floods may occur due to the limited bank full capacity of the local drainage system. This flood causes a significant loss of both infrastructures and human life. One of the most significant efforts in reducing this flood risk is the improvement of Cengkareng Drain channel as the main drainage system in the area. Cengkareng Drain conveys the flow of Angke River and Mokervaart River into the Java Sea passing through Tangerang and Jakarta. This paper discusses about the contribution of several alternatives of improvement in reducing the related flood risk. The flood hazard is analysed based on the standard criteria of PUPR. The risk analysis is done in accordance to the BNPB guidebook. Based on this study, it is found that the drainage existing condition may cause a high flood risk level in 5 areas and an average risk level in 1 area. This flood risk could be reduced by applying both structural and non-structural mitigation efforts. It this case, it is found that structural mitigation of dike development combined with non-structural mitigation of local community capacity development is the most effective solution.

Watershed prioritization for the identification of spatial hotspots of flood risk using the combined TOPSIS-GIS based approach: a case study of the Jarahi-Zohre catchment in Southwest Iran

Flash flooding caused by excessive rainfall in a short period of time is one of the worst environmental hazards, especially in arid and semi-arid regions. Watershed prioritisation identifies and ranks the different watersheds in a catchment based on multiple parameters, which play a role in the land and water degradation. This article deals with the prioritization of 24 sub-catchments in the Jarahi-Zohre catchment in southwest Iran by applying the mixed multivariate linear model of TOPSIS. Morphometric parameters, such as the constant of channel maintenance, drainage density, ruggedness number, infiltration index, stream power index, stream frequency, slope, drainage texture rate, relief rate, form factor, bifurcation ratio, as well as the topographic wetness index, were used as TOPSIS input data, along with precipitation information. The results obtained from the weighting analysis show that ruggedness number, slope and rainfall information have the largest impact on flood events. The sub-catchments Seidyon, Emamzadeh Jafar, and Takht Deraza have a high flood risk and should be given the highest priority for soil and water conservation measures. To validate the results, the prioritization scheme was compared to the flood events in recent years.

Analysis of the Vulnerability of Farm Households to Flood Risk in Punjab, Pakistan

Climate change is the most important challenge for developing as well as developed countries. Pakistan is a developing country and has faced different types of natural disasters such as floods in the last 10 years. The rural areas of Pakistan are adversely affected by floods, which cause significant losses to crops, assets, and the household members face illness, health problems, loss of family income, and displacement. Approximately, 7016 villages with a cropped area of 473998 acres have been affected only in Punjab due to floods during the last four years. The impact of floods is not the same among the different regions, races, ages, classes, and gender. In this regard, a study was conducted to analyze the vulnerability of farm households in three flood-prone districts of Punjab province of Pakistan. These three flood-prone districts have different population size, and are located in high-risk flood region of Punjab was selected for empirical analysis. A well-structured questionnaire was used. Minimum 120 respondents were selected through a random sampling technique. A farm household survey was conducted and a vulnerability index was developed by using well-defined indicators. Three major dimensions of vulnerability were analyzed in detail such as exposure, adaptive capacity, and sensitivity. A multiple linear regression model was used to formulate the results. The analyzed results showed that flood was the main cause of the destruction of houses, livestock, and destruction of agriculture production. Results showed that farm household communities were the most vulnerable and floods hazard has a negative impact on the livelihood of human beings and the economy of Punjab as well.

Implications of Basement Inclusion in Buildings in High-Risk Flood Zones in Yenagoa, Nigeria

Recent and past studies have shown that buildings without cellars or basements are considered to be most appropriate for flood-prone areas. However, a number of buildings constructed with basements have been observed in High-risk flood areas in Nigeria such as Yenagoa. This paper uses a case study approach to examine some of these buildings in the selected areas and the implications or effects of having such subterraneous spaces in these locations without the proper waterproofing or basement tanking methods. The study showed that although knowledge of pluvial flooding and fluvial flooding exists in this region and are often taken into consideration during building construction, what seems to be lacking is a knowledge of groundwater or basement flooding and its implications in building design and construction. The study also showed the extent to which policies address flooding issues and the areas they fall short.

High water, no marks? Biased lending after extreme weather

Policymakers have put forward proposals to ensure that banks do not underestimate long-term risks from climate change. To examine how lenders account for extreme weather, we compare matched repeat mortgage and property transactions around a severe flood event in England in 2013–14. First, lender valuations do not “mark-to-market” against local price declines. As a result valuations are biased upwards. Second, lenders do not offset this valuation bias by adjusting interest rates or loan amounts. Third, borrowers with low credit risk self-select into high flood risk areas. Overall, these results suggest that lenders do not track closely the impact of extreme weather ex-post, and that public flood insurance programs subsidize high income households in some areas.

Failure risk assessment method of masonry structures under earthquakes and flood scouring

Flood scouring can expose the foundation and cause stiffness degradation of masonry structures and is often overlooked by designers and engineers. The seismic performance of a structure cannot be guaranteed when stiffness degradation reaches a certain critical level, which is usually difficult to control. Investigating structural performance under the combined action of earthquakes and flood scouring is very significant for regions that have both a high seismicity and a high flood risk. In this paper, a method for evaluating the failure probability of masonry structures under flood scouring and earthquakes based on risk theory is proposed. According to the performance requirements of masonry structures under natural hazards, the performance indexes of structures are quantified, and the fragility of masonry structures under the combined action of flood scouring and earthquakes is analyzed. Flood scouring and earthquake hazard risks and structural fragility under multiple hazards are comprehensively considered to obtain the structural failure exceedance probabilities in different damage states. Then, the critical scour depth at which the seismic resistance of the structure drops abruptly due to flood scouring is calculated. Furthermore, the loss ratio and the cumulative failure probability of a structure are introduced to determine the failure risk and reliability index of the structure in the full-performance state and to ultimately evaluate the multihazard structural performance. Based on the method proposed in this paper, the multihazard failure risk of a one-story masonry structure is analyzed. The results show that earthquakes are the main force controlling the structural performance, and flood scouring has a relatively small influence on the fragility of structures in slight damage and moderate damage states and a relatively large influence on structures in severe damage and collapse states. In addition, a critical scour depth exists, beyond which the structural fragility changes sharply. Compared with the failure risk of the case in which only earthquakes are considered, the failure risk of the structure under each damage state increases substantially when the combined action of flood scouring and earthquakes is taken into account. Therefore, the influence of flood scouring on the seismic performance of structures must be considered.

Hemodialysis Clinics in Flood Zones: A Case Study of Hurricane Harvey

Hurricane Harvey (2017) forced the closure of hemodialysis centers across Harris County, Texas (USA) disrupting the provision of dialysis services. This study aims to estimate the percentage of hemodialysis clinics flooded after Harvey, to identify the proportion of such clinics located in high-risk flood zones, and to assess the sensitivity of the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps (FIRMs) for estimation of flood risk. Data on 124 hemodialysis clinics in Harris County were extracted from Medicare.gov and geocoded using ArcGIS Online. The FIRMs were overlaid to identify the flood zone designation of each hemodialysis clinic. Twenty-one percent (26 of 124) of hemodialysis clinics in Harris County flooded after Harvey. Of the flooded clinics, 57.7% were in a high-risk flood zone, 30.8% were within 1km of a high-risk flood zone, and 11.5% were not in or near a high-risk flood zone. The FIRMs had a sensitivity of 58%, misidentifying 42% (11 of 26) of the clinics flooded. Hurricanes are associated with severe disruptions of medical services, including hemodialysis. With one-quarter of Harris County in the 100-year floodplain, projected increases in the frequency and severity of disasters, and inadequate updates of flood zone designation maps, the implementation of new regulations that address the development of hemodialysis facilities in high-risk flood areas should be considered.

Coastal protection assessment: a tradeoff between ecological, social, and economic issues

AbstractMarine coastal ecosystems are crucial to human populations in reducing disaster risk. Least Developed Countries are particularly vulnerable to the effects of climate change, such as sea‐level rise and storm surges. The Mauritanian coast, West Africa, ranks among the most vulnerable worldwide to sea‐level rise, and coastal communities in the National Park of Banc d’Arguin (PNBA) are particularly at risk. Here, we assessed the service of coastal protection in PNBA by (1) mapping the coastal marine ecosystems with Sentinel‐2 imagery and determining their spatial wave height attenuation rates; (2) assessing the vulnerability of villages and natural habitats to coastal hazard risk; and (3) assessing the applicability of coastal protection measures in the PNBA. We found that a total of 83% of the populated coastline presents a moderate to high risk of flooding and erosion, with Iwik and R’Gueiba being the most threatened villages in the PNBA. As for the ecological risk, two low‐elevated islands, which support breeding colonies of birds, are particularly vulnerable to sea‐level rise. However, in other areas, the rupture in the dune cord created new lagoons that present valuable ecological and economic interests like the Lagoon of Bellaat. Improving the comprehension of wave attenuation provided by coastal habitats, combined with identifying the vulnerability and applicability of coastal protection measures, is essential for achieving the Sendai Framework for Disaster Risk Reduction goals. In the PNBA, relocation of identified villages at risk is probably the best cost‐effective solution with the least disturbance to both breeding and wintering birds. Protection of coastal ecosystems will also ensure a continued provision of other ecosystem services, including food supply for sea dependent populations, and contribute to achieving the Paris Agreement and Sustainable Development Goals.

Is Surabaya being planned as a low-risk city?

Spatial plans are key instruments in directing future developments and reducing a city’s flash flood risk. This study conducts a surface runoff simulation using SWAT analysis in the Kedurus catchment area. SWAT analysis is a hydrological analysis to measure surface runoff from precipitation with consideration of land uses, soil types, climatic data, topography and related infrastructure systems. Based on the simulation, four sub-catchment areas are currently experiencing flash flooding. Surabaya’s detailed spatial plan (RDTR) could reduce the total flood volume in the city by fifty-one per cent if all measures (drainage and other infrastructures) in the plan are implemented successfully. Nevertheless, the implementation of the measures is still questionable due to limited budget and land acquisition. In the case of plan failure, the planned developments will cause higher surface runoff, putting Surabaya is at higher risk of flooding. Therefore, Surabaya needs to diversify its flash flood risk reduction approach to ensure that the plan will achieve a low-risk city in the future.