Hasil untuk "River protective works. Regulation. Flood control"

Giorgio Rosatti, Daniel Zugliani

ABSTRACT The clogging of bridges by loose sediments is a phenomenon that has so far been little studied in the literature but plays a decisive role in determining the spatial distribution of hazards in mountainous areas affected by these events. Lacking a systematic approach, in this paper, we propose a simple scheme describing the physics of bridge clogging derived from some field evidence, identify the requirements that a mathematical‐numerical model must fulfill to be able to implement the scheme, show how the TRENT2D model matches these requirements, and how it is possible to practically implement a procedure for simulating a bridge clogging event. The application to a study area has shown reasonable results, especially regarding hazard mapping. Furthermore, although it was impossible to carry out an in‐depth validation, the proposed approach appears preferable to simplified approaches, such as neglecting the presence of the bridge and its possible clogging or using fixed‐bed modeling with a given increased discharge compared to the liquid estimation. Further investigations will be performed based on field and laboratory data to make the approach even more reliable.

Kıvanç Yüksel, Neşe Gülci, Abdullah Emin Akay et al.

In this study, the effectiveness of different stabilization techniques implemented on the forest road cut slopes was investigated in terms of controlling erosion and runoff. Wood production residues, hydroseeding, and jute geotextile treatments were applied on study plots located on the example road. The amount of erosion and runoff were measured on the study plots which were established for different slope grades of 20°, 30°, and 40°. Then, the amount of erosion and runoff measured from the plots were compared to determine the performance of stabilization techniques on the cut slope. In the solution process, an Artificial Neural Network (ANN) model, which is one of the machine learning algorithms, was used to predict sediment yield from forest road cut slopes. The sediment yields averaged over the three slope grades from highest to lowest were measured as 6.41, 1.16, 0.65, and 0.45 g/m2 in the control plot with no treatment, jute geotextile, hydroseeding, and wood production residues, respectively. The averaged over the three runoff amounts slope grades from the highest to the lowest were determined as 6.82, 3.71, 1.64, and 1.30 mm/m2 in control the plot, jute geotextile, hydroseeding, and wood production residues, respectively. Comparing to the control plot, wood production residues, hydroseeding, and jute geotextile treatments reduced the sediment yields by 14, 10, and 5 times, respectively. On the other hand, wood production residues, hydroseeding, and jute geotextile applications reduced the runoff amount by 5, 4, and 2 times, respectively. As a result, it was found that wood production residues and hydroseeding treatment can be more efficient in reducing the amount of runoff and sediment yield compared to the jute geotextile treatment. The ANN method achieved high accuracy in predicting sediment yield and it was concluded that the ANN can be used as an effective method to evaluate soil slope stabilization techniques.

Ganggang Ke, Shengdong Cheng, Zhanbin Li et al.

Check dams, as one of the most representative soil and water conservation measures in the Loess Plateau region, primarily impact hydrological and hydrodynamic processes by regulating flows of water and sediment. Constrained by reservoir capacity, sediment accumulation within check dam systems affects their ability to intercept water and sediment. However, there has been limited research on the regulatory role of sediment-filled check dams on watershed hydrodynamics. This study focused on small watersheds in loess hilly gully areas and applied the MIKE SHE model to simulate hydrodynamic processes under different scenarios of filled check dam systems. The regulatory effect of different filled check dam system types on watershed hydrodynamics in the study area was analyzed. The results indicate that after sedimentation in various types of check dams, the peak flow can be reduced by 59.68%–68.66%, the flood duration can be extended by 42.74%–375.81%, and the runoff erosion power can be reduced by 62.92%–85.35%. The reduction in flood volume diminishes with increasing sedimentation, reaching a minimum of 2.42%. Moreover, there are varying degrees of reduction in runoff erosion dynamics in the main channels. These findings provide theoretical support for identifying the regulatory potential of sediment-filled check dam systems on hydrodynamic processes in small watersheds.

Wei Wang, Yunqing Wang, Li Huang et al.

ABSTRACT Reserve management of emergency materials for flood control is the basis for the smooth development of flood control emergency work. To optimize the allocation of flood control emergency materials in each emergency node warehouse, a multiobjective optimization model is constructed from the perspective of multiwarehouse collaborative reservation with the shortest transportation time, the lowest storage and transportation costs, and the minimum out‐of‐stock loss. The center of gravity method is used to address demand when constructing the quantitative function of out‐of‐stock loss. The NSGA‐II algorithm was selected to generate the results after the method comparison to ultimately determine the Pareto solution of the model. The TOPSIS method was subsequently used to screen and determine the optimal allocation scheme to rationally determine the reserve sizes of different categories of flood control emergency materials in each warehouse. The Jiangsu provincial warehouse materials were used for empirical analysis. Some of the optimized warehouses (e.g., Zhenjiang and Xuzhou) received increased stock of critical materials such as bags, steel pipes, and shovels, whereas others (e.g., Suzhou and Yangzhou) had reduced excess inventory to avoid overstocking. Compared with the initial allocation, the optimized scheme reduces out‐of‐stock losses by approximately $392,000, lowers transportation costs by over $110,000, and improves the efficiency of flood control emergency scheduling, which can help management make better decisions on the allocation of flood control emergency materials in the future.

Chandra Lal Pandey

ABSTRACT Climate change is one of the biggest threats humanity is facing in the 21st century. Nepal, being a low‐income country located on the lap of the Himalayas, is experiencing a wide range of impacts from changing climate and climate‐induced disasters. Communities of the Kamala river basin are increasingly affected by climate‐induced hazards such as floods. Land use change, deforestation, and climate change‐induced disasters such as landslides, droughts, and floods are affecting the riverine communities. Floods have been one of the most serious threats for centuries; however, their frequency and scope are being amplified by climate‐induced extreme weather events. Employing a convergent mixed‐method approach, this study explored the impacts of climate‐induced disasters, especially focusing on floods in Ward 12 of Siraha and Ward 11 of Dudhauli municipalities in Nepal's Kamala river basin. It investigated the current status of impacts of climate change‐induced disasters; the availability, usage and effectiveness of flood early warning systems; and analyzed local community practices for making communities flood and disaster resilient. The findings suggested that the climate‐induced disasters are becoming key concerns for the communities as they are affecting multiple areas from water security to livelihood options. In addition, the existing early warning systems for floods are still weak. While communities are attempting adaptation strategies including increasing social cohesion, their resilience level is insufficient. This study has made original contribution to the relevant literature and developed applicable knowledge for strengthening local communities' capacities to build climate, flood, and disaster resilience.

Francesco Silvestro, Luca Molini, Fausto Guzzetti et al.

Abstract In compliance with the national legal framework, the regional offices (CFDs) of the Italian Civil Protection Department have the daily duty to issue warnings to the local population on the account of the weather and hydrology‐related impacts, predicted by forecast models and refined through their expertise and experience: this composite of objective (model) and subjective (analyst) assessments are both contributing to the actual colour‐coded warning system. Given its hybrid nature, it is of paramount importance to evaluate the predictive ability of the warning decision‐making process as a whole. To this end, this study compares the return period T of the occurred flood (estimated through an hydrological model fed with observations) to the warning level that was issued. The novelty of this approach is that, by applying this methodology extensively in space and time, the probability curves of the variable T for each warning level are computed, allowing to evaluate the consistency between the warnings and the actual (estimated) severity of the event. As results suggest, the national early warning system is proven to be overall reliable for most cases, though very fine scale events (e.g., severe, localised, short‐lived thunderstorms) are still an open challenge.

Longhui Pan, Rui Li, Benjin Yu et al.

Karst landscapes are plagued by severe soil erosion due to their fractured lithology and complex hydrology, posing persistent challenges to erosion assessment and ecological restoration. However, current approaches often fail to account for the spatial heterogeneity and hydrological complexity typical of karst terrains. This study developed and compared four vegetation restoration scenarios—the status quo scenario, linear scenario, patch scenario, and combined scenario—using an integrated modeling framework based on the Revised Universal Soil Loss Equation (RUSLE) and the sediment connectivity index (IC). The combined scenario, which integrates linear buffers with patch-based vegetation, showed superior performance in reducing both soil erosion and sediment connectivity. The patch scenario also shows strong adaptability in steep-slope areas because it effectively mitigates sediment transport potential. To improve restoration precision further, a slope- and karst desertification-sensitive vegetation configuration strategy was proposed. This study also introduced the use of bivariate Moran's I analysis to identify spatial hotspots of erosion and connectivity overlap. These results provide a novel methodology for evaluating multiscenario ecological restoration in karst regions. The findings offer practical guidance for implementing targeted soil and water conservation interventions and contribute to the broader goal of sustainable land management in ecologically fragile environments.

Dário Hachisu Hossoda, Raphael Ferreira Perez, João Rafael Bergamaschi Tercini et al.

ABSTRACT Urban flooding is a growing challenge in metropolitan areas, exacerbated by climate change and increasing urbanization. This study develops an innovative flood warning system for the Guarará Basin in Santo André, Brazil, leveraging both parametric and machine learning (ML) models. Rainfall data from the São Paulo State Flooding Alert System and historical flood records were processed using the dynamic Thiessen polygon method and advanced statistical techniques. A parametric model was calibrated to define alert thresholds, while a Random Forest (RF) classifier was trained to predict five alert levels: “No Rain,” “Raining,” “Vigilance,” “Warning,” and “Alert”. The models were validated against historical events from 2016 and 2019, demonstrating strong agreement in predicting alert levels and highlighting the benefits of combining physical interpretability with data‐driven adaptability. The ML model achieved an overall weighted F1‐score of 0.99, showcasing its effectiveness in classifying rainfall events and issuing timely warnings. This integrated methodology offers a robust framework for flood risk management in urban areas, contributing to the development of sustainable and resilient cities.

HE Xiao-zhi, YUE Hong-yan, LUAN Hua-long, HUANG Wei-dong, XU Fang

[Objective] Significant recent scouring of the riverbed has been observed near Biandanzhou on the right bank of the Taiziji Reach, potentially threatening dike safety, influencing river regime control nodes, and altering the flow distribution ratio of downstream branches. Meanwhile, the navigation conditions in the main channel of Donggang on the right branch remain unstable. [Methods] To ensure flood control and navigation safety, this study analyzed the recent riverbed evolution of the Taiziji Reach based on the latest original underwater topographic observation data and long-term measured records. The study also predicted river regime development trends and proposed corresponding preventive and control measures to address existing issues. [Results] The shoreline has remained generally stable over the years. Except for the straight reach from Changhekou to Xingfucun, the thalweg has shown limited variation. The most significant platform migration, with a maximum lateral migration of approximately 1.1 km, was recorded in the Biandanzhou-Xingfucun area. The thalweg elevation generally exhibited a lower upstream and higher downstream pattern, with alternating changes in elevation over time. The -5,-10, and -15 m contour lines showed a slight overall scouring trend in the deep channel. The Tietongzhou branch would continue to exhibit a pattern of left branch and right main channel, with the right branch showing a general scouring trend. Locally, severe scouring near Biandanzhou was evident inter-annually, with the right bank retreating by approximately 700 m between 1981 and 2021 and the maximum local depth of scouring in the riverbed about 12 m. [Conclusions] It is recommended to implement protective measures as soon as possible for the severely scoured sections near Biandanzhou. Continuous enhancement of hydrological and topographic monitoring and follow-up analyses is essential. Once issues are identified, engineering interventions such as river regulation works should be promptly adopted. The results of this study provide critical technical support for future river management strategies in the Taiziji Reach under new flow-sediment conditions.

Yudong Wang, Xida Yu, Lanjia Yi et al.

Abstract The traditional flood hazard assessment system for emergency departments is based on the average hazard index of administrative regions. However, this approach may overlook errors with significant hazards caused by the transition from watershed hazard maps to administrative hazard maps. In our study, we propose an innovative approach that utilizes fuzzy sets to represent flood risk grades, incorporating the upper and lower boundaries of membership variety to effectively indicate higher and lower risks errors, respectively. The introduction of fuzzy set risk grades not only incorporates conventional information but also addresses local risk errors caused by the conversion, enabling Emergency Departments to allocate disaster prevention funds accurately for all risk spots. The fund allocation coefficient, based on fuzzy risk grades, strongly correlates with the proportion of flood‐affected populations over time, highlighting the robustness of utilizing fuzzy set risk grades.

Alison C. Rudd, Alison L. Kay, Paul B. Sayers

Abstract An increase in extreme weather events is leading to increased flood occurrence and risk in many areas. Although climate mitigation strategies are being implemented, it is widely accepted that societies must adapt to climate variability and climate change. Traditional climate change impact studies have used projections for future time‐slices, often for a range of possible emissions scenarios. Recently however, there has been a move to instead consider climate change impacts relative to global mean surface temperature (GMST) change, to try to encourage action to avoid the more severe impacts from higher GMST changes. To support adaptation planning, more localised information on impacts is required. Here, data on the potential range of changes in flood peaks is generated by combining flood response surfaces and the new UK Climate Projections 2018, for every river cell on a 1 km grid across Britain, for GMST changes of 1–4.5°C. The results show significant spatial variation, with impacts typically higher in the west than the east, and generally increasing with GMST change. Some southern regions show flood peak changes accelerating with GMST change. The changes in flood peaks can be translated into changes in flood inundation and associated flood risk under alternative adaptation assumptions.

پریسا فتاح, خسرو حسینی, سید علی اصغر هاشمی

مقدمهخاک یکی از مهمترین منابع طبیعی هر کشور است که نقش کلیدی در امنیت غذایی، اقتصاد ملی و کشاورزی پایدار ایفا می­‌کند. فرسایش خاک، از بارزترین عوامل هدررفت خاک است که فرسایش بارانی از شکل­‌های مهم آن است. از این‌رو، شناخت دقیق فرایندهای حاکم بر فرسایش خاک و انتقال رسوب در زمینه مدیریت صحیح منابع آب و خاک به‌­منظور رسیدن به توسعه پایدار و همچنین توسعه مدل‌­های فرسایش خاک از اهمیت بالایی برخوردار است. پژوهش‌­های پیشین نشان داده است که الگوی بارش از عوامل تاثیرگذار بر فرسایش بارانی است. پوشش گیاهی نیز با حفظ خاک در برابر اثر قطرات بارش و رواناب از فرسایش خاک می­‌کاهد. در مناطق خشک و نیمه­‌خشک، با توجه به کمبود پوشش گیاهی و رطوبت اولیه بسیار کم خاک، فرسایش بارانی اهمیت ویژه دارد. این پژوهش با توجه به تاثیر الگوی بارش بر فرسایش بارانی و با بررسی الگوی بارش و تغییرات پوشش گیاهی طی 25 سال در دو حوزه آبخیز ابراهیم‌‌­آباد و رویان شهرستان سمنان انجام گرفت.مواد و روش‌­هابرای انجام این پژوهش، ابتدا ویژگی­‌های فیزیکی حوزه‌­های آبخیز با کمک نرم‌افزار ArcGIS به‌­دست آمد و اطلاعات بارش از باران‌نگار با دقت 10 دقیقه، استخراج شد. به­‌منظور مقایسه بارندگی­‌ها با مقادیر متفاوت بارش، منحنی بی ­بعد بارش تجمعی هر رویداد به‌دست آمد. زمان هر بارش به 10 گام زمانی تقسیم شد و برای دهک­‌های زمانی آن (گام‌­های زمانی)، درصد مقدار بارش مشخص شد. دسته­‌بندی رگبارها بسته به این­که وقوع بیشینه بارش در کدام چارک زمانی اتفاق افتاده است، به چارک­‌های یک، دو، سه، چهار تقسیم‌­بندی شد. با توجه به بیشترین مقدار بارندگی بارش در هر چارک، الگوهای آن نامگذاری شد. با توجه به اطلاعات لایه­‌های رسوبی در سد­های کوتاه مخزنی واقع شده در خروجی هر حوضه و اطلاعات بارش، رگبارهای مربوط به هر لایه رسوبی مشخص شد و تاثیر الگوی رگبار بر الگوی رسوب مورد بررسی قرار گرفت. برای بررسی شباهت الگوهای بارش و رسوب، از معیارهای میانگین اختلاف در هر گام بارش و رسوب و تغییرات انحراف استاندارد استفاده شد. با نگرش به تغییرات پویای پوشش گیاهی نسبت به دیگر ویژگی­‌های حوضه برای بررسی تغییرات پوشش گیاهی و مساحت آن از داده‌­های سنجش از دور استفاده شد. با توجه به عملکرد موثر و دقت زیاد شاخصNDVI  و تصاویر ماهواره‌­ای لندست در مناطق خشک، برای برآورد پوشش گیاهی، مدیریت و فراخوانی تصاویر ماهواره‌­ای، سامانه Google Earth Engine مورد استفاده قرار گرفت. سپس، به بررسی تاثیر ویژگی­‌های حوضه از جمله شیب، مساحت، جنس خاک، ضریب شکل حوضه و پوشش گیاهی مناطق بر رسوبدهی حوضه­‌ها پرداخته شد.نتایج و بحثنتایج نشان داد، میانگین شباهت‌ها در الگوی بارش و رسوب در حوضه­‌های ابراهیم‌­آباد و رویان به‌­ترتیب 48.2 و 46.1 درصد بوده است. همچنین، با افزایش شماره چارک بارش، درصد رسوبات درشت‌­دانه نیز طی هر رگبار افزایش یافت که گویای نقش مهم الگوی رگبار بر الگوی رسوبدهی حوضه­‌ها است. میانگین ماهانه پوشش گیاهی (حاصل از تصاویر لندست) در حوضه‌­های ابراهیم‌­آباد و رویان در طی دوره مذکور به­‌ترتیب 5.15 و 4.99 درصد به‌دست آمده است که نسبت به پژوهش‌­های پیشین کمتر برآورد شده است. در این پژوهش، از حد آستانه 0.1 برای شاخص NDVI استفاده شده است که در آن از پوشش‌­های گیاهی بسیار ضعیف صرف‌نظر شده است.نتیجه­‌گیریدر مجموع می­‌توان بیان کرد که در هر دو حوضه در بیش از 51 درصد موارد، با افزایش پوشش گیاهی در هر رگبار، ضخامت لایه رسوب مربوطه کاهش یافته است که تاثیر مقادیر و تغییرات پوشش گیاهی بر فرسایش و رسوب حوضه­‌ها را بیان می­‌کند.

Valeria Pennisi, Rosaria Ester Musumeci, Rosario Grasso et al.

Abstract Animal activities threaten levee stability, especially during flood events, increasing levee failure risk. Indeed, while dens alter hydraulically‐induced failure mechanisms, it is difficult to locate them and to know in advance if critical conditions may be reached. This paper demonstrates that it is possible to perform nondestructive surveys to assess the risk of burrow animal activities in levee systems using a ground penetrating radar (GPR) for effective levee structure control, being GPR a nondestructive, expeditious, and cost‐effective geophysical technique. Here, a flood‐prone area in Sicily, where traditional hydraulic phenomena did not justify past levee failure events, is considered a case study. Through a visual inspection survey, several animal holes were recovered. GPR measurements allowed us to explore the levee interior and to detect the presence, distribution, and configuration of dens inside them. It was found that a complex burrow system crosses the entire embankment. Porcupine was recognized as a builder of such cavities. Although, previous studies established the porcupine presence in semi‐humid environments, for the first time, here we provide evidence of the development, articulation, and extension of porcupine burrows inside the levee system.

Cinzia Albertini, Domenico Miglino, Vito Iacobellis et al.

Abstract The geomorphic flood index (GFI) method provides a good representation of flood‐prone areas. However, the method does not account for floodwater transfers in undefined interbasins (UIBs), which represent intercluded small basins along the coastline likely to be flooded by adjacent major rivers. The present work addresses this shortcoming by complementing the GFI approach with an iterative procedure that considers UIBs and water transfers between basins. The methodology was tested on a coastal basin in southern Italy and the outcome was compared with a flood map obtained by a two‐dimensional hydraulic simulation. GFI performance as a morphological descriptor improved from 74% (standard method) to 94% with the addition of the iterative procedure. The proposed methodology, with the same parameterization, was applied on a second adjacent coastal basin obtaining improvements both in terms of true positive (from 56 to 79%) and false negative rates (from 44 to 21%). Finally, a sensitivity analysis to the flood return periods highlighted a strong influence on model parameterization for return periods below 20 years. This achievement represents a new development in the application of the GFI method, which can help stakeholders in a more time‐ and cost‐effective flood risk management in hazard‐prone areas.

Ebrahim Hamid Hussein Al‐Qadami, Zahiraniza Mustaffa, Mohamed Ezzat Al‐Atroush et al.

Abstract Watercourses and roadways commonly intersect in their layout at many locations through bridges, drainages, and fords. During heavy rain events, watercourses may overflow causing serious disturbance toward traffic movement. Under such circumstances, attempting to drive through these intersections can be extremely dangerous. Therefore, understanding the responses of the vehicles moving through floodwaters is of utmost importance. Between 1967 and 2021, several studies have been published investigating the stability of static flooded vehicles. However, studies on the stability of vehicles in the movement are not sufficient at which only few experimental studies were published. Herein, for the very first time numerical simulations were conducted to investigate the hydrodynamic forces on a full‐scale medium‐size passenger vehicle moving perpendicular to the incoming floodwaters. Sliding and floating instability modes were observed by detecting the position of the vehicle centre of mass at each time step. Further, horizontal (FH) and vertical (FV) forces were measured and plotted against the governing flow parameters. Finally, it was observed that the critical flow depth was 0.38 m, while the minimum depth×velocity threshold function was 0.39 m2/s, for the tested vehicle. Later, a comparison between simulation outcomes and previously published experimental work was performed and a good agreement was observed.

Jie Liu, Hong Xiao, Pengzhi Lin et al.

Abstract In order to investigate the relationship between water surface velocity and breach hydrograph, a series of dam breach experiments with a generalised landslide dam were conducted in an open channel of 50 m × 4 m × 2 m. The large‐scale particle image velocimetry (LSPIV) technique was applied to measure the time history of water surface velocity during the dam breach process, and the hydrography was obtained by integrating the surface velocity along the water depth. The influence of different vertical velocity profile approximation and suspended sediment concentration on the peak breach discharge were analysed and discussed. The results showed that the water depth over the breach crest can be described as a function of water surface velocity using d¯t=k22u¯surf2/k1g. A simple formula based on surface velocity and breach width for the estimation of breach discharge was further proposed and verified.

Tigstu T. Dullo, Sudershan Gangrade, Mario Morales‐Hernández et al.

Abstract Using the 2017 Hurricane Harvey flood event as a test case, this study set up a series of sensitivity analyses to highlight three challenges associated with large‐scale flood inundation modeling, including (a) model parameterization, (b) errors in digital elevation models, and (c) effects of reservoir retention. Driven by radar‐based hourly rainfall data, a series of hydrologic‐hydraulic models including the VIC hydrologic model, RAPID routing model, and Flood2D‐GPU hydrodynamic model are set up over Harris County, Texas, to simulate flood inundation and hazards. The results demonstrate the importance of hydrologic parameters in improving flood modeling. For a large flood event such as Hurricane Harvey, the effect of the initial water depths is insignificant. The Manning's n values may increase the peak water depth by ~1%, the flood extents by 65km2, and the high danger zone by ~6%. On the contrary, the bathymetry correction factors may reduce the flood extent by ~1.4% and the high‐danger zone by ~4%. Reducing the reservoir storage capacity to 1% may increase the flood extent by ~4% and the high‐danger zone by ~17%. This study may provide supporting information to guide and prioritize the development of future high‐performance computing hydrodynamic large‐scale flood simulations.

Federica Zabini, Valentina Grasso, Alfonso Crisci et al.

Abstract The study of risk perception (RP) has much increased in the last years to improve flood risk management. Effective communication requires an understanding of how the risk of flooding is perceived by residents of different areas. In this work, RP is investigated through a survey involving 483 people living in Tuscany. RP was assessed through a score built on four items covering personal, residence, and sociodemographic variables concerning flood RP. Results showed that: (a) flood RP was moderate; (b) RP was positively correlated with age, higher education, proximity to a river and direct experience; (c) people who experienced floods felt themselves to be more informed and prepared; (d) subjectively perceived risk and experts' risk assessment seemed generally correlated, even if people living in areas at “high risk” tend to underestimate the actual flood risk level; (e) the majority of the respondents considered the government and themselves as equally responsible for personal preparedness; and (f) less than 20% was aware of a Local Emergency Plan. The need of focusing on people living in the riskiest areas with targeted communication campaigns on risk awareness, hazard preparedness, and other implications of the findings in terms of communication strategies are discussed.

Naoki Koyama, Tadashi Yamada

All metropolitan cities in Japan are located in low-lying areas that surround ports. Accordingly, significant floods that occur in these cities will trigger the simultaneous occurrence of flooding by river water and inland flooding. However, existing studies have focused on the impact of flooding by river water, inland flooding, and high tide in tidal rivers, and disaster mitigation measures focused on detailed flooding processes in such flooding areas have not been conducted thus far. This study focused on a tidal river, i.e., Katabira River of Yokohama city, one of Japan’s metropolitan cities, to construct a simultaneous occurrence model of flooding by river water and inland flooding, including the impact of a high tide. Numerical analysis was conducted using this model, and the results show that the flooded area significantly changed from 0.004 to 0.149 km2 according to the tide level of the estuary. Moreover, by simultaneously solving the calculation of flooding by river water and inland flooding, we found that there was a difference of 50 min between the occurrences of these floods. Therefore, we found that there is a possibility that, if evacuation is not conducted at the time of occurrence of inland flooding, evacuation during subsequent river-water flooding may not be possible. Based on these results, our proposed method was found to be useful for tidal rivers of metropolitan cities.

Maria Adriana Cardoso, Maria Céu Almeida, Rita S. Brito et al.

Abstract Flood risk management in urban areas adjacent to the coast is essential to increase their resilience. This study aims at improving scientific knowledge of flood risk alongside estuaries, considering different hazards and integrating estuarine and urban drainage modelling. Mathematical modelling of stormwater systems is a useful tool to evaluate the susceptibility to flooding and identify potential measures to reduce flood risk. The assessment of urban drainage flooding uses a coupled 1D/2D model, applying 1D model to the underground system and 2D model for the surface component. Assessment scenarios were based on variables rainfall, estuarine water level, and degree of obstruction in sewers and at system outfalls. Estuarine hydrodynamics were simulated using the SCHISM‐WWM model. A web GIS platform was developed to support urban flood risk forecast and management providing urban analysis visualisation. The main objective is to forecast flooding in the Dafundo catchment supporting definition of population warnings. This paper proposes a flood risk assessment approach, using 1D/2D coupled modelling, estuarine hydrodynamics, integrating the assessment in a forecast web platform. The novelty is supporting an integrated flood risk management in stormwater systems, particularly in estuarine areas, providing an important improvement to assess flooding occurrence, regarding flood depth, area and duration.