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Two behavioural types in sociohydrology of floods have been described in more detail than others: the levee effect and the learning effect. However, additional types of behaviour operate and need further research. Taking the case of frequent flash floods occurring in an ephemeral stream, a tributary of the Vilama River, located in San Pedro de Atacama, Chile, at the interphase between the Atacama desert and the Andean Altiplano, we explore the existence of further behavioural types in the sociohydrology of floods at four neighbourhoods along the tributary. Fieldwork to reconstruct a recent flood event, hydrological analysis and semistructured interviews with key informants to characterize people's responses to floods were conducted. Results show evidence that the so-called status quo effect is present at the riparian community scale, i.e. when communities do not learn and adapt to prevent damage even when exposed to frequent floods. Possible causes of the status quo effect are discussed. [ABSTRACT FROM AUTHOR]

Recent flood disasters caused by extreme meteorological events highlight the need of fast and reliable tools for flooding forecast. For our purposes, the danger associated with floods is embodied in a single risk-level flag which considers both local water depth and velocity. The methodology here derived is applied and validated for the case study of the St. Lucia island in the eastern Caribbean Sea that experiences flash flooding as a result of combined intense rainfall and steep slopes, difficult to predict with traditional early-warning systems. A multi-layer perceptron neural network is trained on a high-fidelity dataset generated through full two-dimensional shallow water simulations of real and synthetic events. The dataset is validated against social markers obtained from real events. The predictive capabilities of the neural network model are tested on the out-of-box case of the Dean and Tomas hurricanes and compared with the solutions of the shallow water solver. The surrogate solver allows a significant speed-up in the prediction time with respect to traditional CFD (seconds vs hours), showing a high precision and accuracy, with accuracy, precision and F1-score above 0.99. [ABSTRACT FROM AUTHOR]

This study addresses a crucial gap in our understanding of flooding in the predominantly agricultural Qaa'Jahran watershed in Yemen, where urbanization, though currently limited in extent, is rapidly expanding. We aim to discern the effects of earth fissures on flood dynamics, particularly focusing on their present significance. It is noteworthy that, in the long run, these fissures are anticipated to accumulate soil and sediment, potentially heightening the risk of future flooding. To achieve this, we developed a comprehensive floodplain delineation model, incorporating field observations and rainfall data from the Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm. Additionally, advanced hydrologic and hydraulic models were integrated to accurately simulate runoff hydrographs and create flood inundation maps. Our findings underscore the considerable influence of earth fissures, effectively mitigating runoff volume, peak discharge, flood depths and inundated areas during storm events. It is imperative to emphasize that specific areas remain persistently vulnerable, with water levels surpassing one meter during historical floods. This reinforces the ongoing risk of flooding in targeted zones and emphasizes the necessity of implementing tailored flood management strategies. In conclusion, this study makes a significant contribution to the field, providing a comprehensive analysis of the intricate factors influencing flooding in the Qaa'Jahran watershed. The integration of flood inundation mapping, advanced hydrologic modelling and meticulous consideration of earth fissures offers a distinctive perspective on flood dynamics in a rapidly evolving and urbanizing environment. Furthermore, it highlights the critical implications for effective flood risk management and urban planning, not only in the Qaa'Jahran watershed but also in similar urbanizing regions worldwide. [ABSTRACT FROM AUTHOR]

Flash floods are one of the most serious mountain disasters in Linzhi, China, pose a grave threat to the lives and property of the residents. However, the current regional vulnerability research cannot meet the needs of refined disaster prevention and mitigation in mountainous areas. Therefore, to address this knowledge gap, this study presented a vulnerability assessment framework base on spatialization technique along with the triangular fuzzy number-based analytic hierarchy process (TFN-AHP) and random forest (RF) model. To achieve this goal, an assessment system containing 12 indicators was constructed from the three perspectives of exposure, susceptibility and coping capacity. Firstly, factor spatialization is introduced in data preprocessing. Then TFN-AHP and the RF model were used to calculate the exposure, susceptibility, and coping capacity. Finally, the spatial distribution of the vulnerability throughout Linzhi was obtained. According to the results, the exposure, susceptibility and coping capacity in most areas are extremely low and low, accounting for 74.1%, 99% and 99%, respectively. The vulnerability is similar to the exposure that most of the regions have extremely low vulnerability and low vulnerability, accounting for 83.5%. The moderate vulnerability regions account for 8.5%, and the high vulnerability regions account for only 1%. The assessment results show that highexposure areas mainly exhibit a linear distribution, and mainly include river valleys, cultivated land, and residential areas. Obviously, these areas are mainly distributed in the population and economic agglomeration areas and on low-altitude terrain. The distribution of high and comparatively high vulnerability zones, where economic and human activities are considerably high, are closely to the topography of the catchment. Thus, the results of this study provide scientific and technological evidence for resettlement, population distribution adjustment, and prevention and mitigation of flash floods in Linzhi. [ABSTRACT FROM AUTHOR]

Flash flood can cause dramatic damages to the infrastructure of transportation networks. Because of the uncertainty of flash floods and the access function of roads, assessing the impact of flash floods on transportation systems has been a great challenge. In this study, we proposed a framework for evaluating the risk posed by flash floods to transportation network, which considers the interruption probability of road links and the expected impact on the access function of transportation. To assess the probability of interruption, we used the random forest model to output the flash floods susceptibility. Then, a multiple centrality model was used to evaluate the expected impact when a link was interrupted. The risk takes into account the flash floods susceptibility and road multiple centrality, and it identify critical links. Using the natural break points method, the result of flash floods susceptibility, road multiple centrality and risk were divided into five levels: extremely low, low, moderate, high and extremely high. Approximately 30.8% of the roads were found to be at high and extremely high risk, and most of these roads were located in Sichuan and Yunnan provinces. The flash floods susceptibility contributes more to the risk than the road multiple centrality, thus, further study should be focused on the areas with high flash floods susceptibility. We discussed different disaster prevention and mitigation measures for the different types of high risk links. The results can improve our understanding of the risks posed by flash floods to road networks. The proposed generalized network risk analysis method provides a new perspective and tool for analysing the impact of flash floods on road network. [ABSTRACT FROM AUTHOR]

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The flash flood in the town of Mandra, Attica, in 2017 that had a return period equal to approximately T = 150 years was one of the most disastrous floods in Greece. Four years later, flood protection works designed for T = 50 years were built. In this work, we pose the research question 'How would this disastrous flood have behaved if flood protection works were built?' To answer this question, we employed the HEC-RAS 1D/2D model, over a detailed DSM, that we calibrated with field measurements to simulate the flood of 2017. We derived the following conclusions: (1) Flooding of the main streets still occurs with 15–25% lower flow velocities and 19–29% lower water depths. (2) The total extent of the inundation areas is reduced by 17%. (3) Works delay flood arrival by approximately 1.5 hour, thus providing the opportunity for an Early Warning System to respond more effectively. [ABSTRACT FROM AUTHOR]

The increasing flash floods phenomenon in arid and semi-arid regions of Algeria has led to a search for practical and feasible solutions. The use of mapping to delineate floodplain areas has become one of the solutions to mitigate this phenomenon. El Bayadh city has experienced a catastrophic flood on 1 October 2011 causing significant human and material damage. The present study aims to produce a flood hazard map of El Bayadh city based on rainfall amounts. Four precipitation values were proposed 40, 60, 80, and 100 mm, through which four flooded areas were obtained. This flood hazard map proves its effectiveness when used in conjunction with the weather warnings issued by the National Office of Meteorology. In this work, a hydrological study was done, and ArcGIS and HEC-RAS software were used. [ABSTRACT FROM AUTHOR]

The objective of the study on which the article is based was to investigate the distribution, characteristics and livelihood effects of debris cones in the Aba'ala and Raya grabens in Ethiopia. The characteristics of the debris cones and their upper catchment areas were obtained from Google Earth Pro and Landsat images. Questionnaires were used to understand the livelihood effects of the debris cones. In addition, transect studies, interviews and observations were used to supplement the data. The data were analysed using descriptive statistics, a regression model and coupled criteria. The results showed that the debris cones differed in their physical characteristics and distribution, and their volumes were larger in the Raya graben than in the Aba'ala graben. The average flow lengths of the upper catchments was the major predictor of debris cone volume. The expansion of debris cones devastated farmlands, resulting in crop yield loss. Moreover, deposited debris damaged dwellings and pasture, and led to smallholder farmers' displacement. However, the cones remained attractive for settlement and spate irrigation. The authors conclude that despite the benefits of debris cones, catchment rehabilitation measures should be implemented in the upper catchments to reduce the expansion of debris cones in the studied grabens. [ABSTRACT FROM AUTHOR]

Flash floods continue a trend of costly disasters attributed to changing weather patterns and climate disruptions. Small and Medium-Sized Enterprises (SMEs) are more vulnerable and ill-prepared to flash flooding, compared to their larger counterparts, so they are disproportionately affected by such extreme weather events. This study reports on the results of a quantitative survey of SME owners/managers and employs quantile regression analysis in an attempt to shed light on factors affecting resilience barriers to flash floods. Findings suggest that the effect of organizational size on SME barriers is reduced as barriers increase. In contrast, the effect of organizational age is found to be positive with low magnitudes when barriers are either very low or considerably high in contrast to negative effects when barriers are at moderate levels. A positive influence of the industrial affiliation at all barrier levels is also identified. Previous experience with flash flooding events as well as the effect of profitability are found to have negative impact in most levels of analysis. The assessment highlights the need for targeted intervention and assistance to the various segments of the SME sector through customized guidance and/or ad hoc regulation by focusing on factors explaining barriers to resilience. [ABSTRACT FROM AUTHOR]

Integrated with K-means clustering and Apriori algorithm, the multi-level association rule mining is proposed to investigate the causal factor patterns of flash floods, which consists of the following three steps: first, the association between causal factors and flash flood occurrence is being analysed; second, to identify the contribution of soil moisture (SM) to flash flood hazards, the association between risk indicators and SM, and the linkage between SM and risk magnitude are being discussed; finally, with the consideration of total 24-h rainfall and SM pattern, the association rules for risk magnitude are extracted. The method has been tested in a humid area of southern China, results show: (1) flash flood hazards are especially active after the prolonged and periodic intense rainfalls, and because of the saturated SM, flash floods are easily triggered even by slight rainfall; (2) severe flash floods are easily triggered by extreme rainfall, and SM is the critical indicator of 5-year floods and 20-year floods; and (3) owing to the differences in steady infiltration rate and instability in soil type, conservation of water and soil is an indispensable and co-ordinate part of flood control. Results are expected to be applicable for decision-making in flood control and flood prediction. [ABSTRACT FROM AUTHOR]

Flooding impacts can be reduced through application of suitable hydrological and hydraulic tools to define flood zones in a specific area. This article proposes a risk matrix technique which is applied on a case study of Taibah and Islamic universities catchment in Medina, Kingdom of Saudi Arabia (KSA). The analysis is based on integration of the hydrologic model hydraulic models to delineate the flood inundation zones. A flood risk matrix is developed based on the flood occurrence probability and the associated inundation depth. The risk matrix criterion is classified according to the degree of risks as high, moderate and low. The case study has indicted low to moderate risk for flood frequencies of 5 years return periods and moderate to high risk may exist for flood with rerun period of 50 and 100 years. The results are projected on a two-dimensional satellite images that shows the geographical locations exposed to flooding. A quantitative summary of the results have been presented graphically to estimate the magnitude of the inundation areas that can assess the degree of damage and its economic aspects. The developed flood risk matrix tool is a quantitative tool to assess the damage which is crucial for decision makers. [ABSTRACT FROM AUTHOR]

Flash floods cause extensive loss of property and human life. Early warning systems present a more efficient approach to flood prevention and mitigation than engineering measures. This article reviews research on flash flood early warnings in China, including long-term prediction methods based on statistical regularity and flood mechanisms, and real-time warning indicators relying on multi-source data and automated systems. Current research shortcomings are discussed, and suggestions for future improvements are proposed. This research can provide public officials with knowledge of flash flood early warnings, influencing policy and protecting people from flash flood disasters. [ABSTRACT FROM AUTHOR]

Flash floods occur periodically in the hilly areas of Argentina but since they generally occur at inhabited areas, these are rarely registered. Several factors contribute to the occurrence of flash floods: heavy seasonal rains, rugged topography and geological structures. On Thursday night 23 January 2014 an extreme rainfall event took place in El Rodeo, Catamarca Province, triggering an unexpected flash flood. This flood caused 14 fatalities and great economic losses in the main localities of the Ambato Department. Steep slope gradients facilitated the quick drainage of the precipitated volumes. Water, boulders and debris channeled downstream caused severe stream bank erosion and major damage to houses roads and bridges. This paper presents a morphometric analysis in order to determine some geomorphic characteristics of the Ambato River basin together with a preliminary analysis of the flood hazard potentially damaging to inhabitants and infrastructure to downstream villages. The study was carried out using high-resolution satellite data acquired before and after the event. The drainage networks were derived from Aster GDEM V2 and satellite images. [ABSTRACT FROM AUTHOR]

Bryndal, T. 2015. Local flash floods in Central Europe: A case study of Poland.Norsk Geografisk Tidsskrift–Norwegian Journal of Geography. Vol. 69, 288–298. ISSN 0029-1951. The article focuses on the seasonality, geographical distribution, and hydrometeorological aspects of local flash floods in Poland, in Central Europe. Scientific articles describing local flash flood events were studied and a database of such floods in Poland was developed and analysed. The results revealed that local flash flood events were usually generated by rainfall lasting less than two hours, with a mean intensity in the range 20–80 mm·h-1. The triggering threshold for local flash floods was P = 20 mm·h-1. Local flash floods may occur from April to October, with higher frequencies in May, June, and July. The floods usually affect mountain and uplands areas differently to lowland and basins regions, and this might be explained by heavy rainfall distribution and topographical conditions. The maxima of the unit discharge (Qs) describe an envelope curve according to the equation Qs = 47A-0.4(where A is the catchment area in km2). The maxima appear very consistent with envelope curves proposed for other inland continental European countries. The authors conclude that local flash floods in Poland are similar to those recorded in inland continental areas of Europe, but differ from the floods in the Mediterranean part of the continent. [ABSTRACT FROM AUTHOR]

Accurate flash flood prediction depends heavily on rainfall data quality and knowledge of catchment behaviour. A methodology based on global sensitivity analysis and hydrological similarity is proposed to analyse flash storm-flood events with a mechanistic model. The behaviour of medium-sized catchments is identified in terms of rainfall–runoff conservation. On the basis of this shared behaviour, rainfall products with questionable quantitative precipitation estimation (QPE) are excluded. This facilitates selection of rainfall inputs for calibration, whereas it can be difficult to choose between two rainfall products by direct comparison. A substantial database of 43 flood events on 11 catchment areas was studied. Nash-Sutcliffe efficiencies for this dataset are around 0.9 in calibration and 0.7 in validation for flash flood simulation in 250-km2catchments with selected QPE. The resulting calibration framework and qualification of possible losses for different bedrock types are also interesting bases for flash flood prediction at ungauged locations.Editor D. Koutsoyiannis [ABSTRACT FROM PUBLISHER]

t Spatio-temporal storm properties have a large impact on catchment hydrological response. The sensitivity of simulated flash floods to convective rain-cell characteristics is examined for an extreme storm event over a 94 km2semi-arid catchment in southern Israel. High space–time resolution weather radar data were used to derive and model convective rain cells that then served as input into a hydrological model. Based on alterations of location, direction and speed of a major rain cell, identified as the flooding cell for this case, the impacts on catchment rainfall and generated flood were examined. Global sensitivity analysis was applied to identify the most important factors affecting the flash flood peak discharge at the catchment outlet. We found that the flood peak discharge could be increased three-fold by relatively small changes in rain-cell characteristics. We assessed that the maximum flash flood magnitude that this single rain cell can produce is 175 m3/s, and, taking into account the rest of the rain cells, the flash flood peak discharge can reach 260 m3/s.Editor Z.W. Kundzewicz; Guest editor R.J. MooreCitation Morin, E. and Yakir, H., 2013. Hydrological impact and potential flooding of convective rain cells in a semi-arid environment. Hydrological Sciences Journal, 59 (7), 1275–1284. http://dx.doi.org/10.1080/02626667.2013.841315 [ABSTRACT FROM AUTHOR]

Recent studies on climate change indicate a growing frequency and intensity of flash flood events in western Europe. Flash floods are caused by extreme local precipitation. The URBAS project is concentrating on the urban occurrence of flash floods in Germany. URBAS has as a main objective to increase the preparedness and the range of possible actions of urban actors (e.g. communities, public enterprises) before and during rare small-scale flood events. Within URBAS the meteorological parameters, runoff and damage of flash floods are investigated. Innovative and feasible actions and precautionary measures at a reasonable cost-value-ratio are to be developed. [ABSTRACT FROM AUTHOR]

Abstract: Flash floods are characterized by their suddenness, fast and violent movement, rarity, small scale but high level of damage. They are particularly difficult to forecast accurately and there is little lead time for warning. This makes motorists especially vulnerable. Assuming that these flash flood hazard specificities may be the significant factors leading to difficulties for drivers to perceive danger, we used cognitive mapping combined with GIS data processing to assess motorists’ flash flood risk perception on their daily itineraries. The analysis of 200 mental maps collected allows planners to have maps highlighting dangerous areas where risk perception is weak and to identify reasons for this. [Copyright &y& Elsevier]

In many tropical island settings in the world and as a result of human activities and tropical weather conditions, urban areas have been vulnerable to special kinds of hazards. The most common and the most widely experienced hazard events for these localities are tropical cyclones and accompanying storm surges, flash floods and landslides. Such events can cause serious damages to the drainage systems, roads, properties, receiving environment and even the loss of human lives. Given the threats of climate change, such natural disasters are likely to strengthen this trend in the coming years. In many situations, it is the population living in low-lying urban areas that are most exposed to these disasters. From this, it follows that the scientific and professional communities have a responsibility to evolve better stormwater management approaches directed to minimizing hazard risks owing to urban flooding, even while addressing different climatic conditions. Although, the physics, chemistry and biology of processes related to water are universal, some of the processes and implementation of measures to manage water vary in terms of the climate conditions, geographical location, availability of resources and local culture. In tropical island conditions, where flash floods occur frequently, alongside the obvious structural measures, effective non-structural measures, such as better hazard mitigation and prevention, improved preparedness and introduction of warning systems, well organised pre-emptive action and emergency response activities, have to be coupled together in order to minimize damages. Furthermore, as the management of urban flooding is an emerging subject, it is necessary to understand that such a topic needs to be treated holistically, and so in a multi-disciplinary manner. This implies that the public, town planners, economists, lawyers, emergency services, and many other groups need to be involved, along with the engineers, surveyors and contractors, in developing strategic plans for hazard reduction, operational management and post-event recovery. Thus the stakeholders have to be involved in the decision-making processes (e.g., Abbot 2007, available at www.eiil.net). The present paper describes an integrated stormwater management approach oriented towards the small islands in tropical climates which continuously tend to suffer from flash floods. The approach outlined here draws on the work experiences gained in the Caribbean. [ABSTRACT FROM AUTHOR]

Each year flash floods cause considerable property damage and loss of life, yet the heavy precipitation events responsible for flash floods remain extremely difficult to forecast, especially during summer. This paper presents synoptic analog models for use in the shod-range prediction of summertime extreme rainstorms in Minnesota. To develop these analog models, forty-three heavy rain events that occurred from 1974-78 first were classified into four similar categories on the basis of the spatial properties of their rainfall distributions. Next, composite fields of surface and upper-air parameters were prepared for each of the four categories, and features on the composite maps that contributed most to the occurrence of heavy rainfall were incorporated into synoptic analog models. The analog models reveal that the typical circulation patterns for the four rainfall types vary significantly and that the spatial characteristics of extreme rainstorms are determined by the synoptic-scale circulation regime in which the rainstorms form. This interrelationship between the spatial characteristics and atmospheric circulation can be used to improve subjective forecasts of location and areal extent of extreme rainstorms. The results of this study also indicate that the preparation of synoptic analog models for local areas can improve our understanding of the climatology of heavy precipitation. [ABSTRACT FROM AUTHOR]

In the subtropical Atlantic rain forest of southern Brazil, reproduction of the catfish Pimelodella pappenheimi was studied over a two years period in a small coastal stream representing a widely undisturbed aquatic habitat. According to analyses of the gonad status, reproduction is mainly seasonal with a peak in the rainy summer months, consisting of multiple spawning. The average body length of the fishes attaining sexual maturity was the same in both sexes. At the study site summer storms cause flash floods, and heavy rainfalls can suddenly increase the river flow. Reproductive females were found to burrow in the clay palisades of the river sediments which is regarded a behavioural adaptation protecting the offspring from being washed away. [ABSTRACT FROM AUTHOR]

Flood forecasting is a core of flood forecasting and flood warning system which can be implemented by both conceptual rainfall–runoff (CRR) model and black-box rainfall–runoff (BBRR) model. Dynamic artificial neural network (DANN) as an innovative BBRR model and HEC-HMS as a traditional CRR model were used for flood forecasting. The aim of this paper is to compare the efficiency of HEC-HMS and DANN for the determination of flood warning lead-time (FWLT) in a steep urbanized watershed. A framework is proposed to compare the performance of the models based on four criteria: type and quantity of required input data by each model, flood simulation performance, FWLT and expected lead-time (ELT). Finally, the results show that FWLT and ELT were estimated longer by DANN than by HEC-HMS model. In brief, because of less required data by BBRR model and its longer ELT, future research should be focused on better verification of it. [ABSTRACT FROM PUBLISHER]