Extreme Flood Research Articles

Factors affecting household evacuation decision making in response to disaster: Case study from the 2021 South Kalimantan floods, Indonesia

Understanding the factors that influence evacuation decisions is crucial for optimizing resource allocation and formulating an effective emergency plan, particularly in the communication and implementation of warnings. To assist with this endeavour, this study investigates whether selected variables affected evacuation decision-making during the 2021 South Kalimantan, Indonesia, Floods. This is achieved through identifying significant factors in a binomial regression model constructed using a resident survey during the extreme floods of January 2021 and the more typical frequent floods of December 2021. The survey captures sociodemographic, capacity-related, hazard-related and warning-related factors from 375 residents including 205 in West Banjarmasin (urban area) and 170 in Tabuk River (rural area). It was found that families with partial ownership of their house (renting or living with another family) and those with a higher number of members are less likely to evacuate, as are those with a lack of knowledge about evacuation shelters and routes. External factors influencing people's evacuation decisions included the flood height and duration as well as whether there was an unofficial warning to evacuate. The findings suggest the following actions could assist with encouraging safety-seeking behaviour through evacuation: ensure evacuation instructions reach larger families and households and that they are relevant for them; include evacuation instructions with warnings; and conduct regular evacuation drills that include information about the flood risk map and the location and route to relevant evacuation shelters.

Hydroclimatic change and vegetation response in Tropical African alpine environments over the Holocene

Future precipitation is highly uncertain, particularly in East Africa where model projections contradict modern observational trends. Climate changes in East Africa's mountains are even less well understood, yet these mountains are threatened by warming, extreme flooding, fires, and the rapid disappearance of glaciers. Paleoclimatic and paleoenvironmental records can contextualize ongoing and future changes; however, proxy records from East African mountains disagree with each other and, in some cases, differ from nearby lowland sites. It is unclear if these discrepancies are due to geographic or altitudinal gradients in climate or processes that impact the fidelity of climate proxies in these mountains. To better understand past mountain precipitation and vegetation change, we produced three new records of the hydrogen and carbon isotopic composition of terrestrial leaf waxes (δ2Hwax and δ13Cwax) spanning the Holocene using lake sediment cores collected from Lake Mahoma (2990 m asl), Lake Africa (3895 m asl), and Lake Kopello (4017 m asl) in the Rwenzori Mountains, Uganda-Democratic Republic of Congo. We find similar trends at all three sites in reconstructed precipitation hydrogen isotopic composition (δ2Hprecip), which we interpret to reflect precipitation amount. Our records show drying occurred during the Younger Dryas (∼12 cal ka BP), enhanced precipitation during the African Humid Period (∼10-5 cal ka BP) and drying in the mid to late Holocene (∼5-0 cal ka BP), similar to adjacent lowland sites. We observe a gradual termination of the African Humid Period in the Rwenzori, consistent with many regional records. We also observe distinct patterns of Holocene precipitation change in Eastern and Western Africa, indicating differences in the delivery of moisture from the Atlantic and Indian Oceans. Despite changes in precipitation over the Holocene, the carbon isotopic composition of the waxes in Rwenzori lakes indicates constant C3 vegetation and eco-hydrological stability, in contrast to sites from lower elevations. This likely indicates climate remained humid and cool enough throughout the Holocene to maintain forest and alpine plant communities at these high-elevation mountain sites.

Cost-benefit analysis of working with recovery in river management using Marxan

With the impact and cost of continued river degradation and climate change-induced extreme rainfall and floods, there is growing urgency to achieve and maintain good river health to meet global sustainable development goals. Up-scaling and working with nature-based solutions at regional, catchment and fluvial corridor scales is critical. One way to achieve this is to work within a recovery-enhanced approach to river rehabilitation, incorporating processes of geomorphic and vegetative recovery to build fluvial corridors in areas where they have become fragmented. Geomorphologically-informed cost-benefit analysis has not previously been applied in a riverine or riparian context, at the catchment or regional scale needed. We applied Marxan in a novel manner to undertake the first cost-benefit analysis for geomorphologically-informed rehabilitation of river systems. We estimated that to rehabilitate 75,500 km of streams in coastal catchments of NSW will cost $8.2 billion, comparing favourably to recent single flood event insurance losses, and projected future losses. We developed Marxan scenarios based on three broad approaches to river management: ad hoc and reactive, working with recovery and corridors, across current and future time periods. We found there are considerable current and flow-on future financial and non-financial benefits, and lower initial total and per-hectare rehabilitation costs, by fully adopting working with recovery or corridors approaches and moving away from the ad hoc and reactive approaches which dominate current practice. Implementing targeted rehabilitation based on a rolling sequence over time of corridors scenarios provides optimal holistic solutions to improve geomorphic condition and enhance recovery potential at landscape-scale. Our study demonstrates the use of Marxan as an accessible tool to address prioritisation complexity, and to run and cost landscape-scale rehabilitation scenarios over time. Our study also demonstrates the positive offsite feedbacks that occur through multiplier effects, as recovery occurs, and corridors are built. Geomorphologically-informed decision making becomes more robust, transparent, cost-effective, consistent across catchments, and adaptive to local situations and evolving river management priorities.

Influence of data source and copula statistics on estimates of compound flood extremes in a river mouth environment

Abstract. Coastal and riverine floods are major concerns worldwide as they can impact highly populated areas and result in significant economic losses. In a river mouth environment, interacting hydrological and oceanographical processes can enhance the severity of floods. The compound flood hazards from high sea levels and high river discharge are often estimated using copulas, among other methods. Here, we systematically investigate the influence of different data sources coming from observations and models as well as the choice of copula on extreme water level estimates. While we focus on the river mouth at the city of Halmstad (Sweden), the approach presented is easily transferable to other sites. Our results show that the choice of data sources can considerably impact the results up to 10 % and 15 % for the river time series and 3 % to 4.6 % for the sea level time series under the 5- and 30-year return periods, respectively. The choice of copula can also strongly influence the outcome of such analyses up to 13 % and 9.5 % for the 5-year and 30-year return periods. Each percentage refers to the normalized difference in return level results we can expect when choosing a certain copula or input dataset. The copulas found to statistically best fit our datasets are the Clayton, BB1, and Gaussian (once) ones. We also show that the compound occurrence of high sea levels and river runoff may lead to heightened flood risks as opposed to considering them independent processes and that, in the current study, this is dominated by the hydrological driver. Our findings contribute to framing existing studies, which typically only consider selected copulas and datasets, by demonstrating the importance of considering uncertainties.

Integrated approach for flood shelter site selection and emergency response accessibility analysis at the provincial scale: a case study in Henan, China

ABSTRACT Emergency response efficiency is affected seriously by shelter location during traffic disruption caused by floods. In this paper, a new framework including the suitability assessment of shelter location and the accessibility analysis of emergency response is proposed. Firstly, an evaluation criteria system from a risk perspective is established to screen candidate shelters. Secondly, candidate shelters’ effective area, capacity, and service radius are combined to determine the suitable shelter locations. Finally, the emergency accessibility of traffic under different rainstorm scenarios is calculated, respectively. The results show that resident emergency congregate shelters are suitable to be built in economically developed and highly densely populated areas around the central part of Henan, and it is mainly to guard against extreme floods caused by heavy rainfall. It should be dominated by emergency evacuation and embarkation shelters to prevent daily floods in the west and southwest. In addition, the reduced accessibility is apparent in the western and southeastern regions owing to road inundation, and occurs in the disaster scenarios of the 20-year return period and more. This study suggests how to select suitable shelters by considering the spatial heterogeneity of the province.

Urban Built Environment and Flood Ramifications: Evidence from Insurance Claims Data in Miami, Florida

This study examines the role of the urban built environment in mitigating or exacerbating flooding. By analyzing census tract-level insurance claims in Miami, we model such relationships during moderate and extreme flood events. Our findings indicate that lower population density, higher urban compactness, and proximity to coastal and riparian zones are linked to elevated flood insurance claims. The study also highlights the potential of nature-based solutions in alleviating flood impacts during extreme events. These insights provide crucial empirical evidence for urban planners and policymakers to adopt a systemic approach considering density, location, and nature-based solutions to foster climate-resilient cities.

Potential contribution of land cover change on flood events in the Senegal River basin

The increase in flood events observed in West African countries, and often in specific river basins, can be influenced by several factors, including anthropogenic land use and land-cover changes. However, the potential contribution of land cover changes to flood events still needs to be explored, especially in West Africa. Here, the fully coupled atmosphere-hydrology WRF-Hydro system, which comprises an atmospheric model and additionally incorporates the surface, subsurface, overland flow, and channel routing, is used to investigate the potential impact of a land cover change scenario on flood events in the Senegal River basin. The simulation was performed from 2010 to 2020, with a calibration period spanning from 2011 to 2012 and a validation period from 2013 to 2020. Several skill scores, including Nash-Sutcliffe Efficiency (NSE), BIAS, and Kling-Gupta Efficiency (KGE), were utilized to assess the calibration and validation performances. Additionally, two planetary boundary layer schemes (PBL5 and PBL7) were used to determine their associated uncertainty. Our results show that the best calibration results (NSE = 0.70; KGE = 0.83; PBIAS = −7% and BE = 0.67) in the Senegal River basin are obtained with PBL5 when the calibration is performed with a SLOPE parameter 0.03. A similar good performance was also obtained for the validation with NSE = 0.74, KGE = 0.84, and PBIAS = −8%. Likewise, our findings indicate that converting savanna to woody savannas can elevate water resources, with a 2% rise in precipitation and a 4% increase in runoff. This transition also correlates with an increase in moderate flood events (3500–4000 m3/s), a decrease in severe floods (4000–5000 m3/s), and their associated occurrence of extreme floods (>5000 m3/s) in the Senegal River basin.

Hurricane-induced dramatic decline and natural recovery of a vulnerable sportfish population: Shoal bass (Micropterus cataractae) in the Chipola River, Florida

Freshwater fishes are among the most biodiverse vertebrate groups and among the most threatened by anthropogenic activities. Many occur in small and geographically restricted populations that are increasingly subject to catastrophic events (hurricanes, wildfires, extreme floods and droughts), but it has rarely been possible to assess the impacts of such events. Here we document the decline and recovery of a regularly monitored, small shoal bass (Micropterus cataractae) population in the Chipola River, Florida following a catastrophic hurricane disturbance. The Chipola River population has the lowest level of interspecific hybridization (over 90 % non-introgressed shoal bass) within the species' range, a census population size of 2165 (95 % CI [1,383, 3,801]) in 2009 and a genetically effective population size Ne of 135 (95 % CI [70, 472]). In 2018, Hurricane Michael devastated the Chipola River and watershed. A survey conducted in 2019 indicated a severe decline (91 %) in relative population abundance and a very low Ne at 21 (95 % CI [16, 29]). However, the detection of young-of-year fish indicated that the depleted population had experienced successful reproduction. In fall 2021, the census population had recovered to 1039 fish (95 % CI [660, 1,814]) and Ne at 40 (95 % CI [31, 50]). While the population has shown considerable resilience in the face of hurricane disturbance, it remains vulnerable to future catastrophic events and may also suffer a long-term reduction in its adaptive potential due to a relatively low effective population size. To address these threats, continued monitoring is necessitated and targeted measures such as translocation of non-introgressed individuals from neighboring populations or establishment of a captive population of sufficient effective population size may be required to conserve the species in the long term.

Dioxin-like and estrogenic activity screening in fractionated sediments from a German catchment after the 2021 extreme flood

BackgroundThe flood in July 2021 is considered one of the largest flood disasters in Western Europe in decades, with massive socio-economic consequences. The potential emission and remobilization of anthropogenic pollutants can lead to additional environmental consequences, which need to be addressed in long-term mitigation strategies. The Inde River and its tributary, the Vichtbach River, form a catchment located at the transition from the low mountain ranges of the Eifel to the lowlands of the Lower Rhine Embayment in Germany. The area has been an industrial and mining hotspot for centuries, making it a high-risk area for flood sediment pollution. The present study provides an ecotoxicological screening of flood sediments of the Vicht–Inde catchment to gain an impression of the degree of contamination by organic pollutants by means of in vitro effect-based method. Sediment samples were collected within days after the flood and fractionated prior to biotesting, and supportive instrumental geochemical analysis was performed.ResultsFlood sediments did not reveal estrogenic potential, which was included in the testing strategy as a relevant endpoint for industrial chemicals and untreated wastewater. In contrast, moderate-to-high dioxin-like activity was observed in 70% of the sediment samples with a peak dioxin-like potential at the restored section of the Inde. Overall, four hotspot samples were identified as at risk, which aligned mostly with the high concentration of organic pollutants including PAHs and PCBs. The fractionation allowed the identification of PAHs and their derivates as the most likely toxicity drivers for dioxin-like activity in the sediments of the Vicht–Inde catchment.ConclusionThe results provide first information on the prioritization of hotspot locations at risk for a detailed ecotoxicological profiling and a post-flood monitoring of organic contamination. The identified sinks of contamination in the floodplain areas can be considered a source for remobilization of pollution in future flood events, which is highly relevant for the receiving Rur River.

Seasonal Variability and Hydrological Patterns Influence the Long-Term Trends of Nutrient Loads in the River Po

This study investigates the long-term trends (1992–2022) of nitrogen and phosphorus loadings exported by the River Po to the Adriatic Sea, to better analyse how changes in hydrology are affecting the timing and magnitude of river nutrient loads. We used 30 years of monitoring data in order to (a) identify the main temporal patterns and their interactions at a decadal, annual and seasonal scale, (b) estimate precipitation effects on load formation and evaluate whether and to which extent the hydrological regime affects nutrient export across the years and (c) analyse the nutrient export regime at a monthly scale and the main transport dynamic of N and P chemical species (hydrological vs. biogeochemical control). The long-term analysis shows a general decrease of both P and N loadings, but the trends are different between the elements and their chemical species, as well as undergoing different seasonal variations. We found a statistically significant relationships between precipitation and loads, which demonstrates that precipitation patterns drive the exported load at the intra- and interannual time scales considered in this study. Precipitation-induced load trends trigger seasonal changes in nutrient deliveries to the sea, peaking in spring and autumn. The nitrogen decrease is mainly concentrated in the summer dry period, while total phosphorus diminishes mainly in spring and autumn. This mismatch of N and P results in variable molar N:P ratios within the year. The effects of extreme drought and flood events, along with the progressive decrease in the snowmelt contribution to water fluxes, are expected to exacerbate the variability in the N and P loadings, which in turn is expected to perturbate the biodiversity, food webs and trophic state of the Northern Adriatic Sea.

Enhancing streamflow predictions with machine learning and Copula-Embedded Bayesian model averaging

This study proposes a two-step probabilistic post-processing approach that combines different machine learning-based postprocessors through the Copula-Embedded Bayesian Model Averaging (COP-BMA) method to improve the performance of a hydrological model for streamflow predictions. The proposed approach serves a two-fold purpose: firstly, it aims to enhance the accuracy of streamflow predictions, and secondly, it provides probabilistic results that implicitly address the structural uncertainty inherent in different postprocessing methods. We validate our approach by applying it to the Conceptual Functional Equivalent, a lumped hydrologic model utilized for simulating extreme floods during Hurricane Harvey. The validation is conducted across twelve distinct watersheds in the Southeast Texas region at both daily and monthly scales. The findings indicate that the proposed framework significantly enhances the performance of the hydrologic model across the studied watershed. Specifically, on a daily time scale, there is a 23% and 53% improvement in the NSE and KGE respectively, while on a monthly time scale, the framework enhances NSE by 21% and KGE by 25%. Additionally, the MAE (cms) was notably reduced from 4.64 to 2.23 on the daily scale, and from 2.8 to 1.65 on the monthly scale.

Habitat suitability and flood risk modeling for Gazella conservation actions in Mond protected area

Extreme floods are recognized as a major factor contributing to high mortality rates in mammalian populations. The primary objective of this study is to map flood hazards and evaluate habitat suitability within the Mond Protected Area (MPA), near the Mond River. This region is particularly important as it serves as a habitat for the vulnerable gazelle (Gazella subgutturosa). Through field surveys and information gathering, the study examines the effects of flooding on the mortality, distribution, and abundance of this gazelle population.The MaxEnt approach was used to assess habitat suitability, while flood hazard zoning was conducted using the HEC-RAS model. Field studies and the resulting flood hazard map identified three specific locations "Barid," "Rudbor," and "Cham Sheikh" where floodwaters infiltrate the protected area. This infiltration is attributed to riverbank erosion and the absence of protective vegetation in the above areas. The extreme flood on March 20, 2017, significantly increased gazelle mortality rates.By analyzing the maps integrating flood zoning, gazelle distribution, and population aggregation within the MPA, along with field surveys, practical and significant operational measures to enhance the gazelle habitat have been identified. One key measure includes establishing low-elevation platforms in areas where gazelles congregate. Six platforms have been designated, with three marked as "priority one" and three as "priority two," as the most effective solution for reducing gazelle casualties within the MPA. This decision considers factors such as the flood zoning map, gazelle presence, and historical data on locations with a substantial casualty of this species during floods.

Assessing the Hydrologic Response of a Major Drinking Water Reservoir to Extreme Flood Events and Climate Change Using SWAT and OASIS

Assessing the Hydrologic Response of a Major Drinking Water Reservoir to Extreme Flood Events and Climate Change Using SWAT and OASIS

Editorial: Designing, operating, and rebuilding infrastructures and lifelines for resilience to extreme flooding

Editorial: Designing, operating, and rebuilding infrastructures and lifelines for resilience to extreme flooding

Contrasting survival strategies for seedlings of two northern conifer species to extreme droughts and floods.

Lowland northern white-cedar (Thuja occidentalis) forests are increasingly exposed to extreme droughts and floods that cause tree mortality. However, it is not clear the extent to which these events may differentially affect regeneration of cedar and its increasingly common associate, balsam fir (Abies balsamea). To test this, we measured how seedlings of cedar and fir were able to avoid, resist, and recover from experimental drought and flood treatments of different lengths (8-66days). Overall, we found that cedar exhibited a strategy of stress resistance and growth recovery (resilience) from moderate drought and flood stress. Fir, on the other hand, appears to be adapted to avoid drought and flood stress and exhibited overall lower growth resilience. In drought treatments, we found evidence of different stomatal behaviors. Cedar used available water quickly and therefore experienced more drought stress than fir but cedar was able to survive at water potentials > 3MPa below key hydraulic thresholds. On the other hand, fir employed a more conservative water use strategy and therefore avoided extremely low water potential. In response to flood treatments, cedar survival was higher and only reached 50% if exposed to 23.1days of flooding in contrast to only 7.4days to reach 50% mortality for fir. In both droughts and floods, many stressed cedar were able to maintain partially brown canopies and often survived the stress, albeit with reduced growth, suggesting a strategy of resistance and resilience. In contrast, fir that experienced drought or flood stress had a threshold-type responses and they either had full live canopies with little effect on growth or they died suggesting reliance on a strategy of drought avoidance. Combined with increasingly variable precipitation regimes, seasonal flooding, and complex microtopography that can provide safe sites in these forests, these results inform conservation and management of lowland cedar stands.

The Mediterranean Pond Turtle shows resilience to extreme flood events

The Mediterranean Pond Turtle shows resilience to extreme flood events

Possibilities and limitations of anticipatory action in complex crises: acting in advance of flooding in South Sudan.

Little evidence exists on the design and implementation of anticipatory action (AA) in complex crises. This article examines a 2022 United Nations 'early action' pilot in South Sudan in advance of extreme flooding. As a case study of efforts to act in a complex crisis, it contributes to learning on assisting conflict-affected and displaced populations in advance of extreme weather events. The research points towards the possibility and value of implementing forecast-informed early action in complex contexts with limited forecast skills and multiple hazards when trigger-based AA is not possible. It also argues for the need to link AA implemented in complex crises to development and peacebuilding actors and processes. More broadly, examining the perceptions and processes of AA in the form of early action, rather than a formal AA framework, is highly relevant for the AA community as attention is increasingly placed on providing AA in countries affected by fragility and conflict.

Extreme sea levels and floods: the case study of Klaipėda City, Lithuania

Klaipėda City is located in the Southeast Baltic Sea region, where sea level rise has been observed for decades. The Klaipėda Strait, which separates the Baltic Sea and the Curonian Lagoon, where the port is located, is also more prone to sudden extreme changes in water levels, usually caused by windstorms. Extreme sea level changes pose a threat to port operations, technical structures, city residents, buildings, and infrastructure. Fluctuations in sea levels also affect the water level of the Danė River, which enters the Klaipėda Strait and divides the city into two parts. Therefore, this study aims to determine the past extreme sea level events and their influence on floods in the Danė River within Klaipėda City from 1961 to 2022. For this, the impact of meteorological parameters caused dangerous sea level rises in the Klaipėda Strait, and the following rise of the Danė River was studied. The results show that the annual mean, annual mean maximum, and annual mean minimum water levels in the Klaipėda Strait increased from 1961 to 2022. Also, the number of events where the water level in the Klaipėda Strait was ≥ 100 cm in the Baltic Elevation System was increasing. The increasing frequency of extreme water level events in the Klaipėda Strait puts urban areas at greater risk from Danė River compound floods.

철도산업과 기후변화대응

The railroad industry is the best means of transportation to respond to climate change, as it is more energy efficient than the automobile and aircraft industries and emits about six times less greenhouse gases. As of 2018, the transportation sector of railroads emits 2.6% of greenhouse gases, but greenhouse gases should be reduced by converting diesel locomotives to new and renewable energy locomotives and electric locomotives. However, the Framework Act on the Railway Industry, the Railroad Safety Act, the Railroad Construction Act, and the Railroad Business Act do not have legal and institutional mechanisms to respond to climate change or adapt to the climate crisis. Review the legislation and precedents of France and the United States to seek implications for Korea. The Framework Act on the Railway Industry shall establish and implement the national freight and passenger transport sharing rate and the greenhouse gas reduction target, and shall be improved to include matters on climate change and response to the climate crisis in the national policies and basic plans. The Railway Construction Act should also monitor the effects of climate change, such as extreme heat waves, extreme cold waves, extreme strong winds (types), extreme floods, and extreme wildfires, analyze the cost-benefit analysis of adverse effects on railway infrastructure to build them in advance, and maintain them to improve the quality of railway infrastructure, and include climate change response and adaptation to the climate crisis in the railway network plan. The Railway Business Act and the Railroad Safety Act should be revised to ban the operation of diesel locomotives in stages, such as California and the United Kingdom, to raise funds for the conversion of diesel locomotives to environment-friendly locomotives, report their status to the Minister of Land, Infrastructure and Transport, and stipulate that diesel locomotives cannot be idled for more than 30 minutes. Finally, railway stations and structures should be installed with geothermal power plants and solar power plants, and certified as carbon-zero buildings.

Maintenance of High Phytoplankton Diversity in the Danubian Floodplain Lake over the Past Half-Century.

Riverine floodplains are recognized as centers of biodiversity, but due to intense anthropogenic pressures, many active floodplains have disappeared during the last century. This research focuses on the long-term changes in phytoplankton diversity in the floodplain lake situated in the Kopački Rit (Croatia), one of the largest conserved floodplains in the Middle Danube. The recent dataset from 2003 to 2016 and historical data from the 1970s and 1980s indicate high phytoplankton diversity, summarising 680 taxa for nearly half a century. The variability of species richness is driven by specific in-lake variables, particularly water temperature, water depth, total nitrogen, pH, and transparency, determined by a redundancy analysis of the current data. The high phytoplankton diversity levels are sustained regardless of intense pressures on the lake environment, including exposure to strong anthropogenic pollution in the past and extreme hydrological events, both droughts and floods, which have increasingly affected this part of the Danube in the last decades. The conserved hydrological connection between various biotopes along the river-floodplain gradient seems crucial in maintaining high phytoplankton diversity. Accordingly, conserving natural flooding is mandatory to maintain high biodiversity in complex and dynamic river-floodplain systems.