Flood Marks Research Articles

Reconstruction of the historic flood of 1813 on rivers in the mountains of the Western Carpathians (Slovakia)

ABSTRACT The catastrophic flood of 1813 that occurred in the Western Carpathians region was the largest natural disaster ever recorded here. The 1812/1813 winter season was very cold with abundant snow cover. Spring and summer months were also rich in liquid precipitation, further increasing soil saturation and catchment runoff. Torrential rains were reported to occur from 24 to 26 August when two deep low-pressure systems met over the Western Carpathians above the headwaters of large rivers like Váh and Hron. This resulted in a flood with the flood wave being 10 m above the long-term river stage. In this study we summarize the findings from our archival research to report on the causes, severity and extent of the 1813 flood. Using three-dimensional terrain modelling we have reconstructed the culmination water level in two towns affected by the flood from the rivers Váh and Hron using historical maps and preserved flood marks.

Evolution of the Flood Mark and Built-up Areas in Flooded Lands in the City of Guarapuava, Paraná

Floods are important disaster-generating events in Brazil and in the city of Guarapuava, located in the central region of the state of Paraná. With this in mind, the aim of this study was to investigate the spatial distribution of the flooded area in the city of Guarapuava in different periods, as well as to assess the infrastructures that could be affected. The methodological procedures consisted of photointerpretation from satellite images of the urban infrastructure present in 2014 and 2023 in the flooded area and geospatial comparison of the maximum flood spot mapped before and during the extreme event. The results show that more than half of Guarapuava's neighborhoods (61%) have areas susceptible to flooding and that the most impermeable neighborhoods, in terms of built-up area in the area subject to flooding, are Vila Bela, Industrial and Vila Carli. As well as an increase in urban infrastructure, in an area subject to flooding, of land built from 2014 to 2023, especially in the Morro Alto, Jardim das Américas, and São Cristóvão neighborhoods, with an increase of 2,073%, 373%, and 177%, respectively. Finally, it is concluded that actions to regulate urban land use and risk management strategies are needed to reduce disasters associated with flooding events in the city of Guarapuava.

Incorporating historical flood events in type-based statistics

Flood statistics form the basis of many hydrologic designs. However, short observation periods can lead to a high degree of uncertainty in the quantile estimates, especially for extreme floods. One way to expand the information used in the statistics and, in particular, to include other exceptional floods in the sample is to take historical floods into account. The use of these floods, which are usually reconstructed from chronicles or flood marks, has long been established for classic flood frequency analysis. However, the fact that historical floods can also have different origins and are therefore not statistically identically distributed has so far been ignored. To avoid this violation of the statistical assumptions, we show how historical floods, subdivided according to their genesis, can be taken into account in type-based flood statistics. For this purpose, the classical partial probability weighted moment (PPWM) method is extended for the type-based mixture model of partial duration series (TMPS). The result is compared to a Markov chain Monte Carlo method in order to compare the differences between the two methods. Type-based statistics can also be used to attribute the different influences of historical floods on the quantile estimate. An example shows that floods associated with long-lasting precipitation in particular are overestimated in short samples, while heavy rainfall floods are comparatively well represented. The results show that the consideration of historical events in type-based statistics not only allows a more balanced view of extreme floods, but also enables the influences of these to be attributed.

Historical flood reconstruction in a torrential alpine catchment and its implication for flood hazard assessments

Flood marks and descriptions of past floods in archival records are valuable sources of information to complement the often short – and sometimes lacunary – systematic records provided by gauge stations, especially in mountain and smaller catchments for which the network of recording stations is still fragmentary. Yet, historical accounts of floods are only rarely used to calculate discharge during past floods and to complement estimates of flood frequency and magnitude. This is because the definition of flood types and the reconstruction of past topography of the now urbanized riverscapes is often challenging. Here, we employ an approach by which we combine (i) archival (1331–1965) and continuous gauge (1966–2020) records of past floods, (ii) information on past topography and mitigation measures found on topographic maps and contemporary documents specifying the dimensions of contemporary engineering plans and (iii) a hydraulic model to derive a c. 700-year history of flood activity and related discharges for the Saltina River, Brig-Glis (Valais, Swiss Alps). Periods of increased flood activity match with flood-rich episodes in the Rhone River and high lake levels at Lago Maggiore (Ticino), and the time series passes stationarity tests since at least 1828 CE. For a total of 32 floods occurring prior to the installation of the gauge station in 1966, we provide discharges following a descriptive classification, and demonstrate that major floods occurred in 1755 (∼140 m3s−1), 1828 (∼160 m3s−1), and 1921 (∼120 m3s−1). We also evidence that the construction of mitigation measures has contributed to a reduction in flood frequency, but that the occurrence of extraordinary floods has again been on the rise since the early 21st century.

Use of a national flood mark database to estimate flood hazard in the distant past

ABSTRACT A national flood mark database spanning several centuries contains valuable information to characterize ancient flood events. However, the network of flood mark sites is distinct from the network of hydrometric stations, making this information difficult to use. This work describes a probabilistic model jointly describing flood marks at sites and flood peaks at stations. The model is based on the estimation of hidden climate indices driving both flood marks and peaks: this allows transferring information between the two variables despite them being measured on distinct networks. The model is applied to about 300 flood mark sites (1705–2015) and 200 stations (1904–2015) in France. Results demonstrate that flood marks allow estimating the time-varying probability of exceeding some high discharge threshold at stations during the whole period 1705–2015, which largely predates the existence of stations. The resulting probability maps provide quantitative information on the extent and spatial structure of ancient floods.

Flood Hazard Zoning of Upper Awash River Basin, Ethiopia, Using the Analytical Hierarchy Process (AHP) as Compared to Sensitivity Analysis.

Floods and droughts have been two of the most devastating consequences of the climate crisis affecting billions of people in the world. However, unlike the other natural hazards, flooding is manageable through appropriate flood management mechanisms. This study emphasizes on developing a flood hazard zone for the Upper Awash River Basin (UARB), Ethiopia. Six relevant climate, physiographic, and biophysical factors were considered. Then, a flood hazard map was developed employing the analytic hierarchy process (AHP) method and further validated using sensitivity analysis and collected flood marks. The results revealed that drainage density, rainfall, and elevation have higher significance, while land use and soil permeability have a low impact in the process of flood generation. The map showed vulnerable areas at different levels and can serve as a valuable input for the decision makers to consider in the process of implementing emergency plans as well as long-term flood mitigation options.

Large wood debris that clogged bridges followed by a sudden release. The 2019 flash flood in Catalonia.

Study regionFrancolí River (Catalonia, Iberian Peninsula). Study focusThe aim is the reconstruction of the October 2019 flash flood, that was documented through extensive field work: rainfall (300 mm in just a few hours), flood marks, times of flood passage and witnesses' snapshots and reports, channel changes, log drift (20,000 trees) and woody debris at bridges, as well as large damage and six fatalities. The methods are: hydrological model built for the rainfall-runoff in the basin and the flood routing in the river, use of hydraulic principles such as flow at waterfalls, flow against obstacles (trees), etc. and finally 1D/2D free surface numerical models. New hydrological insightsThe uppermost 100 km2 produced discharges of 700 m3/s (up to 50 m3/s/km2, locally). Three bridges failed, but their cascading failure (when one failure triggers the next one downstream) was not proved. The main channel widened more than 10 times, dragging away soil and vegetation like a bulldozer. The resulting large wood debris that clogged two bridges worsened the inundation. An anomalous flow downstream, probably a surge of around 1090 m3/s, due to the failure of a woody jam at a narrow bridge, took two lives. Water Authority is now warning flood planners that vegetated, torrential basins may cause catastrophic floods in the valley towns, if their narrow bridges are sensitive to woody debris.

A Deep Learning Model of Spatial Distance and Named Entity Recognition (SD-NER) for Flood Mark Text Classification

Information on historical flood levels can be communicated verbally, in documents, or in the form of flood marks. The latter are the most useful from the point of view of public awareness building and mathematical modeling of floods. Information about flood marks can be found in documents, but nowadays, they are starting to appear more often on the Internet. The only problem is finding them. The aim of the presented work is to create a new model for classifying Internet sources using advanced text analysis (including named entity recognition), deep neural networks, and spatial analysis. As a novelty in models of this type, it was proposed to use a matrix of minimum distances between toponyms (rivers and towns/villages) found in the text. The resulting distance matrix for Poland was published as open data. Each of the methods used is well known, but so far, no one has combined them into one ensemble machine learning model in such a way. The proposed SD-NER model achieved an F1 score of 0.920 for the binary classification task, improving the model without this spatial module by 17%. The proposed model can be successfully implemented after minor modifications for other classification tasks where spatial information about toponyms is important.

Application of multiple methods for reverse flow routing: A case study of Luxi river basin, China

Because of the lack of hydrological monitoring facilities and methods in many areas, basic hydrological elements cannot be obtained directly. In that case, the reverse flow routing method is frequently used, which allows for the simulation of hydraulic elements upstream using downstream data, and is of great significance for river and reservoir joint regulation, flood disaster management, flood control evaluation, and flood forecasting. The hydrological and hydrodynamic methods are the two main approaches to reverse flow routing. The hydrological method is mainly realized by constructing a distributed or lumped hydrological model based on rainfall, soil type, terrain slope, and other data. A distributed hydrological model focuses on the physical mechanism of runoff yield and flow concentration, the spatial variability of model input, and the hydraulic connection between different units. The solution of the hydrological method is relatively simple, but it requires a large amount of measured data, which limits the applicability of this method. The other method builds a hydrodynamic model by solving shallow water equations for reverse flow routing. This method has definite physical significance, higher accuracy, and obvious advantages of simple and fast calculations. It can not only simulate one-dimensional but also two-dimensional flood routing processes. In addition, the slope-area method is frequently used for flood reverse routing in many areas in China without relevant hydrological data, and can calculate the peak discharge, maximum water level, flood recurrence interval, and other information by the hydrodynamic formula, along with the cross-section and the measured flood mark water level. Due to the influence of extreme weather, a heavy rainstorm and flood occurred in the Luxi river basin in China on 16 August 2020, resulting in severe flood disasters in this area and causing significant economic losses. Moreover, due to the lack and damage of hydrological monitoring equipment, hydrological information such as flood hydrographs and peak discharges of this flood could not be recorded. To reduce the uncertainty of a single method for reverse flow routing, we integrated and applied the hydrodynamic, hydrological, and slope-area methods to reverse flow routing in the Luxi river basin on 16 August 2020. The simulation accuracy of the three methods was verified in terms of the measured flood mark water level, and the simulation results of the three methods were analyzed and compared. The results are as follows: 1) The hydrological method can better simulate flood hydrographs and durations, especially for flood hydrographs with multiple peaks, and is more applicable than the other two methods. However, the hydrodynamic and slope-area methods have better accuracy in the reverse simulation of flood peaks. Therefore, through the comprehensive comparative analysis of these three methods, flood elements such as flood hydrographs, peak discharges, and durations can be simulated more accurately, and the problem of large errors caused by a single method can be avoided; 2) The simulation results of the hydrodynamic and slope-area methods are similar, and the maximum error of the peak discharge calculated using the two methods is within 10%. According to the simulation results, the peak discharge reached 2,920 m3/s downstream of Luxi river basin, which is a flood having more than 100-year recurrence interval; 3) The simulation results of the hydrological method show that the flow hydrograph is a double-peak, and the two peaks occurred at 17:00 on August 16 and 6:00 on 17 August 2020, respectively.

Reliability of flood marks and practical relevance for flood hazard assessment in southwestern Germany

Abstract. Flood marks are rarely utilized in hazard assessment, mainly because of a lack of data availability and accessibility and mistrust in their reliability. Challenging these common assumptions, we present an approach for evaluation and practical utilization of flood marks by the example of the Kinzig River, a Rhine tributary from the Black Forest with a history of severe floods. We combined written documents describing flood marks with field mapping at three study sites and collected information relating to 89 marks – about 50 % of them still preserved – which refer to ≥15 large floods between 1824 and 1991. The inclusion of a detailed historical-mark survey enabled an assessment of changes through time for each flood mark: they extend from small (±15 cm) imprecisions in mark heights to considerable uncertainties in position, height, and displayed date for some modified marks. Plausibility checks with further data nevertheless demonstrated good overall consistency. We then juxtaposed these marks with the current, modeled flood hazard maps. A wide agreement is apparent, in that the large majority of marks are situated at probable heights and within the modeled flooding area associated with extreme floods. For the few exceptions, we see plausible and historically sound reasons in changed local hydraulic conditions by flood protection walls, exceptional processes during a massive ice jam, and possibly also a local underestimation of hazard along Kinzig River tributaries. Overall, this study highlights (1) the broad availability of flood mark data, both on a larger spatial scale and with regard to already vanished marks, and (2) the significance of the marks, verified by further data, and also demonstrates (3) the possibility of a straightforward inclusion in hazard assessment. We thus encourage the systematic collection, maintenance, and integration of flood marks as responsible risk management, not least regarding their value in the wider context of risk awareness and memory.

Application of hydrological and hydraulic models to quantify surface runoff in the endorheic system of the La Picasa Lagoon basin

The basins in the plain present particularities from the approach of the hydrological processes that take place there. They are characterized by presenting a predominance of vertical water movements (evapotranspiration-infiltration) over horizontal movements (runoff), showing a strong interrelation between surface and underground water. The La Picasa Lagoon basin is defined as a naturally depressed humid pampa region with an undulating plain relief that has low sectors of temporary flooding and permanent lagoons without a defined drainage network. It is an inter-jurisdictional endorheic basin between the provinces of Córdoba, Santa Fe, and Buenos Aires (Argentina) that has suffered recurrent floods between 2014 and 2017 caused by an increase in the average level of the lagoon reaching historical maximums, producing floods, and affecting infrastructure, transport, and agricultural activity. Due to these problems, through the application of hydrological and hydraulic models, the behavior of La Picasa basin system is quantified and evaluated to avoid future floods. In the present work, a hydrological model is applied using the HEC-HMS free tool and a 1D/2D hydraulic model using the HEC-RAS free tool, where the system of channels and reservoirs that make up the system is considered. The flood marks in reservoirs and La Picasa Lagoon are analyzed, and it is defined as regulating the variation of levels in the different reservoirs within permitted ranges. These models are a useful tool for studying future hydrological situations that may occur around the study area.

Prediction of flood discharge and flood flow depth using a hydraulic model and flood marks on the trees in ungauged forested watersheds

It is difficult to estimate flood discharges and the flood zones as well as to design hydraulic structures in rivers without using hydrometric stations. Furthermore, using different models to determine the mentioned cases will be accompanied by errors. Therefore, flood marks on the trunks of trees located in the Babolrood riverbed were used to determine the peak discharge, flood flow depth, and flood zone in northern Iran. First, a hydraulic model for the study river was provided using topographic maps with a scale of 1: 1 000, HEC-GeoRAS extension (GIS), and HEC-RAS model. Then, the flood marks of past floods in the form of silt and clay sediments (deposits on the trees in the riverbed) were evaluated and the maximum flood flow depth was determined. Finally, the peak discharge of the past flood was estimated by the trial-and-error method to achieve the flood flow depth in the different river reaches. Then, the hydraulic model using the flow depth data was calibrated in the reaches, and, in the final step, based on the flood marks of other reaches, the model was validated. According to the results, the maximum instantaneous discharge rate of the study flood was 155 m<sup>3</sup>·s<sup>–1</sup> and the maximum flood flow depth was about 2 m. Furthermore, the results showed that the flood mark data in forest lands can be used as a tool for the calibration and validation of hydraulic models. The present methodology is an efficient method for determining the flood peak discharge, spatial variation of the flood depth, and flood zone in forest watersheds without hydrometric stations.

Numerical Investigation on a Flash Flood Disaster in Streams with Confluence and Bifurcation

On 20 August 2019, a flash flood occurred in Sanjiang Town, Sichuan, China, and caused great damage to people living there. The town lies at the junction of five streams, with streams A, B, and C combining at the town and further dividing into streams D and E. The slope of streams A, B, and C is about 3~5%, while the slope of streams D and E is around 0.3%. The Sanjiang Town actually lies in the transition from supercritical slope to subcritical slope. During the flood, huge sediments were released to streams A, B, and C, and further transported to stream E. Due to the rapid change of velocity, only few sediments deposited at the supercritical slope parts of the stream, while plenty of them sedimented at the streams with subcritical slope. In order to simulate the flood with a hydrodynamic model, a field investigation was carried out to collect high DEM (digital elevation model) data, flood marks, sediment grading, etc., after the flood. The discharge curve of the flood was also obtained by the hydrometric station near Sanjiang Town. For the inlet sediment concentrations of streams A, B, and C, we made a series of assumptions and utilized the case which best fits the flood marks to set the inlet sediment concentration. Based on these data, we adopted a depth-averaged two-dimensional hydrodynamic model coupled with a sediment transport model to simulate the flash flood accident. The results revealed that the flash flood enlargement in confluence streams is mainly induced by the inflows, and the flash flood enlargement in bifurcation streams is largely affected by the sediment deposition. The bifurcation of flows can decrease the peak discharge of each branch, but may increase the flooded area near the streams. Flow in the supercritical slope runs at a very fast velocity, and seldom deposits sediment in the steep channel. Meanwhile, most sediment is transported to the streams with flat hydraulic slopes. Due to the functioning of the reservoir, the transition region from supercritical slope to subcritical slope has a much larger probability of being submerged during the flood.

Low-Frequency Atmospheric Variability Patterns and Synoptic Types Linked to Large Floods in the Lower Ebro River Basin

Abstract This study analyzes the atmospheric variability that caused the largest floods affecting the town of Tortosa, Spain, in the mouth of the Ebro River (northeast Iberian Peninsula). The Tortosa flood database and flood marks in the nearby town of Xerta are used to define the more relevant flooding episodes (discharges >2900 m3 s−1) of the 1600–2005 period. We explore the atmospheric variability based on low-frequency patterns and synoptic types applying a multivariable analysis to grids at sea level pressure and geopotential at 500 hPa provided by the twentieth-century V3 Reanalysis Project for the instrumental period (since 1836). Output from the Last Millennium Ensemble Project was used to analyze the sea level pressure over the pre-instrumental period (before 1836). Our analysis includes 33 flood episodes. Four synoptic types are related to floods in Tortosa since 1836, characterized by low pressure systems that interact with the Mediterranean warm air mass and promote atmospheric destabilization. Flooding in Tortosa is related to relative high values of solar activity, positive Northern Hemisphere temperature anomalies, and NAO in positive phase. This result indicates that the major floods are related to zonal atmospheric circulations (west-to-east cyclone transfer). During winter, the main impact of the floods is located at the western part of the basin, and the Pyrenean subbasins are affected during autumn. The major finding is that similar flood behavior is detected since 1600, improving our understanding of past climates, enhancing the knowledge base for some aspects and impacts of climate change, and reducing uncertainty about future outcomes. Significance Statement A total of 33 large floods (>2900 m3 s−1) were registered since 1600 in Tortosa, Spain, located at the mouth of the Ebro River (northeast Iberian Peninsula). They occur associated with low pressure systems that interact with the Mediterranean warm air mass promoting atmospheric destabilization. The floods in Tortosa are also associated with other important processes occurring at significantly longer time scales: high values of solar activity, positive Northern Hemisphere temperature anomalies, and NAO in positive phase, indicating that the major floods are related to zonal atmospheric circulations. The major finding is that we detect similar flood behaviors since 1600, improving our understanding of past climates, enhancing the knowledge base for some aspects and impacts of climate change, and reducing uncertainty about future outcomes.

Temporary flood marks proposal: What we learned after losing the baroque artifact from Cracow, Poland

For centuries flood marks have been used as a way to preserve the memory of extreme events. In many cities around the world they are considered a cultural heritage and a reminder of historic flood disasters. Their timeless message has endured the ravages of nature over the centuries, but without adequate protection, they risk being irretrievably lost, and with them an important historical message. In Cracow, 21 such artifacts have survived to this day, with the oldest dating back to the 16th century. Yet, the fundamental problem relates to their lack of cataloging and surveying to date. As part of the presented project, we surveyed the preserved marks and recreated the exact location of a lost baroque flood mark using the photogrammetric method, based on preserved photos and images available on Google Street View. Subsequently, this data was uploaded into the public database of the Open Hydrology project. In order to facilitate the reconstruction of flood information in the future, we propose an innovative way of using smartphones to register temporary flood marks. The conclusion from tests on several popular smartphone models suggests the proposed guidelines allow for an inexpensive and quick creation of flood marks with an accuracy of 10 mm. The data collected in a digital format can be used to raise public awareness of floods and is easy to disseminate. Historical flood marks are usually represented in the form of plaques, but are difficult to produce on a mass scale, yet appeal to the imagination. Their digital substitutes can be temporary flood marks photographed with smartphones, so their associated cost is negligible. Furthermore, because they are taken immediately after the flood and not during it (unlike ordinary flood photography), they do not pose a threat to people's safety. The method proposed in this article takes the form of simple guidelines and can be successfully applied for both the quick creation of new temporary flood marks, and for documenting traditional historical marks.

Mitigasi Banjir Berbasis Masyarakat Pada Desa Rawan Banjir Di Kabupaten Barito Kuala

Sungai Lumbah Village and Bangkit Baru Village are two villages that experienced severe flooding in 2021. The flood events occur every rainy season and high tides. The purpose of this study was to analyze community-based flood mitigation in flood-prone villages, Barito Kuala Regency. The research was carried out in two villages, i.e., Sungai Lumbah Village and Bangkit Baru Village, with a total of 50 informants. The results showed that the pre-flood mitigation carried out by the community was by elevating the rice storage area. The community has never received socialization by the local government regarding flood prevention, but they did it on their own initiative and formed a flood alert team. When there was a flood, they set up a relief center to help the affected people. After the flood, the community cleaned up the flood marks in their respective homes and repaired the damaged agricultural land. Flood management is still carried out on the community's own awareness and is carried out voluntarily.

Enhanced flood hazard assessment beyond decadal climate cycles based on centennial historical data (Duero basin, Spain)

Abstract. Current climate modelling frameworks present significant uncertainties when it comes to quantifying flood quantiles in the context of climate change, calling for new information and strategies in hazard assessments. Here, state-of-the-art methods on hydraulic and statistical modelling are applied to historical and contemporaneous flood records to evaluate flood hazards beyond natural climate cycles. A comprehensive flood record of the Duero River in Zamora (Spain) was compiled from documentary sources, early water-level readings and continuous gauge records spanning the last 500 years. Documentary evidence of flood events includes minute books (municipal and ecclesiastic), narrative descriptions, epigraphic marks, newspapers and technical reports. We identified 69 flood events over the period 1250 to 1871, of which 15 were classified as catastrophic floods, 16 as extraordinary floods and 38 as ordinary floods. Subsequently, a two-dimensional hydraulic model was implemented to relate flood stages (flood marks and inundated areas) to discharges. The historical flood records show the largest floods over the last 500 years occurred in 1860 (3450 m3 s−1), 1597 (3200 m3 s−1) and 1739 (2700 m3 s−1). Moreover, at least 24 floods exceeded the perception threshold of 1900 m3 s−1 during the period (1500–1871). Annual maximum flood records were completed with gauged water-level readings (pre-instrumental dataset, PRE: 1872–1919) and systematic gauge records (systematic dataset, SYS: 1920–2018). The flood frequency analyses were based on (1) the expected moments algorithm (EMA) and (2) the maximum likelihood estimator (MLE) method, using five datasets with different temporal frameworks (historic dataset, HISTO: 1511–2018; PRE–SYS: 1872–2018; full systematic record, ALLSYS: 1920–2018; SYS1: 1920–1969; and SYS2: 1970–2018). The most consistent results were obtained using the HISTO dataset, even for high quantiles (0.001 % annual exceedance probability, AEP). PRE–SYS was robust for the 1 % AEP flood with increasing uncertainty in the 0.2 % AEP or 500-year flood, and ALLSYS results were uncertain in the 1 % and 0.2 % AEP floods. Since the 1970s, the frequency of extraordinary floods (>1900 m3 s−1) declined, although floods on the range of the historical perception threshold occurred in 2001 (2075 m3 s−1) and 2013 (1654 m3 s−1). Even if the future remains uncertain, this bottom-up approach addresses flood hazards under climate variability, providing real and certain flood discharges. Our results can provide a guide on low-regret adaptation decisions and improve public perception of extreme flooding.

A Comparative Study of the Effects of the 1872 Storm and Coastal Flood Risk Management in Denmark, Germany, and Sweden

From November 12th to 13th in 1872, an extreme coastal flood event occurred in the south Baltic Sea. An unusual combination of winds created a storm surge reaching up to 3.5 m above mean sea level, which is more than a meter higher than all other observations over the past 200 years. On the Danish, German, and Swedish coasts, about 300 people lost their lives. The consequences of the storm in Denmark and Germany were more severe than in Sweden, with significantly larger destruction and higher numbers of casualties. In Denmark and Germany, the 1872 storm has been more extensively documented and remembered and still influences local and regional risk awareness. A comparative study indicates that the collective memory of the 1872 storm is related to the background knowledge about floods, the damage extent, and the response to the storm. Flood marks and dikes help to remember the events. In general, coastal flood defence is to the largest degree implemented in the affected areas in Germany, followed by Denmark, and is almost absent in Sweden, corresponding to the extent of the collective memory of the 1872 storm. Within the affected countries, there is local variability of flood risk awareness associated with the collective memory of the storm. Also, the economic dependency on flood-prone areas and conflicting interests with the tourism industry have influence on flood protection decisions. The processes of climate change adaptation and implementation of the EU Floods Directive are slowly removing these differences in flood risk management approaches.

Framework of Spatial Flood Risk Assessment for a Case Study in Quang Binh Province, Vietnam

Vietnam has been extensively affected by floods, suffering heavy losses in human life and property. While the Vietnamese government has focused on structural measures of flood defence such as levees and early warning systems, the country still lacks flood risk assessment methodologies and frameworks at local and national levels. In response to this gap, this study developed a flood risk assessment framework that uses historical flood mark data and a high-resolution digital elevation model to create an inundation map, then combined this map with exposure and vulnerability data to develop a holistic flood risk assessment map. The case study is the October 2010 flood event in Quang Binh province, which caused 74 deaths, 210 injuries, 188,628 flooded properties, 9019 ha of submerged and damaged agricultural land, and widespread damages to canals, levees, and roads. The final flood risk map showed a total inundation area of 64,348 ha, in which 8.3% area of low risk, 16.3% area of medium risk, 12.0% area of high risk, 37.1% area of very high risk, and 26.2% area of extremely high risk. The holistic flood risk assessment map of Quang Binh province is a valuable tool and source for flood preparedness activities at the local scale.

Correction to: Strengthening Pluvial Flood Risk Management in the Southeast Region of Bangladesh: Lessons Learnt from the EU Policy and Practice

The trend of flood damages triggered by heavy downpour continues in the southeastern region of Bangladesh due to a lack of non-structural approaches, effective planning and policy. Appropriate guidelines will be needed to develop a robust strategy for improving flood risk management based on advanced technologies, research and practices. The experience gained through the recent EU-funded projects for flash floods, the EU Water Framework Directive and Floods Directive, and the Driver Pressure State Impact Response (DPSIR) framework provide useful insights to solve the problems associated with the flash floods in Bangladesh. Flood marks, post-flood analysis and witness interviews in FLOODsite basins of Europe provide good practices for improving the flash flood risk management. This paper presents normative conclusions from case studies conducted in Feni, Bangladesh on how to manage pluvial flood risk resiliently using strategic planning by considering EU-policy, practice and framework. Interviews were conducted, questionnaires, field observations and focus group discussions were undertaken with the affected community with and without flood experience, national water experts, water management practitioners and local authorities responsible for decision-making on flood risk management. The paper concludes with a number of recommendations for pluvial flood risk management policy making, strategy formulating and practices.