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

Dong Li, Min Zhao, Hailong Zhang et al.

The inland water portion of the carbon cycle is an essential component of the global carbon cycle and is a promising direction to seek missing carbon sinks. Inland waters fix inorganic carbon to form autochthonous organic carbon (Auto-OC) and accept laterally transferred terrestrial OC. Calculating the carbon sink flux of inland water requires a quantitative estimation of the proportion of the aforementioned processes. In the current study, n-alkanes are used as biomarkers and the dual carbon isotope method (Bayesian mixing model) is applied to estimate the proportions of Auto-OC in the sediment of a simulation site comprising five shallow submerged macrophyte-dominated subsystems. The study results showed that a high proportion of Auto-OC was present in all sediment, regardless of the season or subsystem. However, the proportions were higher in the warm-humid season than in the cold-dry season. Results from a correlation analysis showed that temperature-controlled seasonal variations in the photosynthetic strength of aquatic organisms are the most likely cause of this difference. The average deposition rates of total organic carbon and Auto-OC were high (66.7 and 58.2 g C/m2/yr, respectively). Throughout the year, the weighted average percentage of Auto-OC ranged from 76% to 90%, with a mean value of 86% in the five aquatic subsystems. Establishing and maintaining submerged macrophyte-dominated systems have a potential of decreasing carbon dioxide (CO2) evasion and sequestrating more carbon (C) in headwaters. Working for clear submerged macrophyte-dominated lakes is beneficial for increasing carbon sinks.

Dwinata Aprialdi, Reza Mohammadpour, Afri Fajar et al.

Abstract We study a tropical river in South‐East Sumatra, where land drainage in the coastal zone has resulted in subsidence and increased flooding risks, exacerbated by sea tides. The novelty of this research is in determining the effect of tide on the lowland drainage system for forestry in a coastal tropical region and the impact of river cleaning on flood management. Five monitoring stations were set up along the Lebong Hitam river and its primary channels to observe flow characteristics, water level, and bathymetry. The results show how the tide effects water level in the river and the adjacent drainage area with Eucalyptus plantations. Cleaning of the river had a significant effect on each station and increased the discharge and velocity by more than five times and reduced the water depth by more than 40%. In light of this research, it can be concluded that the cleaning up process improves flood risk management by decreasing the water level and increasing the discharge and velocity at each of the upstream stations. The cleaning did not have a significant effect on downstream sections of the river where sea levels control the water level in the river to a large extent. The work provides an analysis of tidal river and provides recommendations for current and future drainage and water management.

Ali Nasiri Khiavi, Mehdi Vafakhah, Dongkun Kim et al.

ABSTRACT This study develops a comprehensive framework for mapping flood susceptibility and vulnerability in the Cheshmeh‐Kileh forest watershed in northern Iran by integrating remote sensing (RS), local knowledge, and machine learning (ML) algorithms. This was accomplished through the application of various MLs, such as K‐nearest neighbor (KNN), random forest (RF), support vector regression (SVR), and Naive Bayes. In this study, flood susceptibility refers to the physical propensity of an area to experience flooding, influenced by geo‐environmental factors, while flood vulnerability captures the socio‐economic and institutional dimensions that determine a community's ability to cope with and recover from flood events. This research first identified critical geo‐environmental factors influencing flood susceptibility and utilized remote sensing to locate areas prone to runoff generation. Flood risk zoning was then implemented using machine learning techniques in Python. To assess flood vulnerability, data were collected from local residents via questionnaires, focusing on economic, infrastructural‐physical, institutional‐policy, and social‐cultural aspects. The flood vulnerability map was created by integrating these survey results with population density data to identify areas where high social exposure coincides with high physical susceptibility. Findings indicated that the combined remote sensing‐SVR model was the most effective for sensitivity classification, identifying sub‐watersheds 2 and 8 in the Sehezar River (a major basin within the study area) as the areas with the highest and lowest flooding susceptibility, respectively, with sub‐watershed 10 in the Dohezar River (another major basin) being the most vulnerable. The estimated values for Mean Absolute Error (0.041), Mean Square Error (0.042), Root Mean Square Error (0.205), and Area Under the Curve (0.980) demonstrated high model accuracy. The Friedman statistical test showed that the average scores for the different dimensions of vulnerability decreased in the order of: economic (0.48), social‐cultural (0.44), infrastructural‐physical (0.34), and institutional‐policy (0.28). Consequently, the economic dimension was prioritized for its highest score. Flood vulnerability mapping revealed that sub‐watersheds 5, 11, 14, and 15, which had higher population densities, were naturally more vulnerable to floods. This finding reflects a direct relationship between population density and flood vulnerability. Overall, this study underscores the urgent need for effective planning and preventive strategies to mitigate flood risks and enhance resilience in the region.

Dawid Aleksander Szatten, Oleksandr Obodovskyi, Marta Brzezińska

The stability of river channels results from the impact of spatially diversified natural characteristics of the catchment, which are additionally intensified by the pressure of human activities. The aim of the current study was the overall assessment of the riverbed stability in the Brda River catchment (Poland) in the two periods 1980–1989 and 1991–2018. The study area is characterized by a high discharge regularity, resulting from the river-lake system in the upper part of the catchment, and strong human pressure caused by the presence of hydrotechnical structures in the middle and lower parts of the catchment. The hydrological, sedimentological, and land cover archival data were used in the current study. Also, in the field campaign, the characteristics of the river channel were delimited. Finally, the erosive stability channel factor is proposed, reflecting the level of pressure on the fluvial system from the catchment. The results show that in the first period, there was a tendency to accumulate sediment on the riverbed, resulting in its instability. However, in the second period, the river channel was stable, and erosion and sedimentation processes did not occur. The links between the stability of the bed of the Brda River, and the temporal and area-related pressures made it possible to identify long-term trends in the degradation of the fluvial environment as a result of human activities and to indicate the directions for sustainable sediment management in the catchment.

Jonathan D. Paul, Aneena Ajmi, Doris Bolaji‐Dada et al.

ABSTRACT Groundwater behavior in superficial gravel aquifers is globally poorly understood, especially across urban regions where drinking water is sourced from elsewhere. This study focuses on one such region around Staines, SE UK, where local River Terrace Gravels form a thin (< 10 m) superficial aquifer. The objective was to explain the unusually broad and long‐lived distribution of flooding by investigating local groundwater level fluctuations and flow. Over a period in January 2024, a targeted citizen science program was instigated to leverage local knowledge of floodwater, which was determined to match groundwater chemistry. Geophysical surveys (ground‐penetrating radar and seismic refraction) were designed to produce high‐resolution water table maps, validated against well measurements. Flow rates and hydraulic conductivity, K, of the gravels were determined both in the field (via pumping and tracer tests) and laboratory, to obviate any scale effects. K depended nonlinearly on hydraulic gradient, with Darcyan behavior breaking down at low (< 0.03) gradients, in conditions approaching turbulent flow. Large and localized fluctuations in groundwater level, combined with the existence of several fast‐flow pathways, are explained by the strong heterogeneity of the gravels, as well as their sensitivity to the imposition of subsurface obstacles such as clay‐lined backfilled gravel pits, or deep basements. These manifestations of urbanization drive observed patterns of groundwater emergence, together with aquifer thickness, rather than changes in river stage or surface elevation alone. Our experience motivates us to suggest that groundwater flooding be considered as significant as fluvial flooding in the production of risk maps by environmental regulatory bodies.

Hongqi Wang, Zixia Liu, Jingyun Feng et al.

ABSTRACT Amidst intensifying climate change, flash floods are becoming more recurrent, posing significant threats to safety and assets, especially in mountainous areas. Given the non‐negligible influence of bridges on flash floods, this research capitalized on fluid dynamics simulations to examine the mechanisms by which six bridges within the investigation zone affect the evolution of flash floods. Moreover, bridge blockage from debris accumulation was methodically investigated under multiple return periods. Results indicated that during the two historical floods, the bridges altered the distribution pattern of flash floods from various flood elements, including the backwater effect, flow velocity, and inundation. It is noteworthy that the spillway bridge (M1) notably raised water levels and slowed flows, whereas the influence of other bridges on flood dynamics was more muted. The presence of six bridges resulted in expanded flooded areas, particularly near the upstream bridges, raising risks for Qishi Village. Furthermore, the increasing blockage ratios at bridge B2 during multiple return periods exacerbated the impacts on flood elements, consequently amplifying the disaster of flash floods. This research strongly emphasizes the importance of incorporating bridges and their blockages into flood risk management. It further provides technical insights to bolster the basin's resilience against extreme hydrological events.

Diego Panici, Prakash Kripakaran, Richard E. Brazier

ABSTRACT Bridge owners and regulatory agencies have a duty to assess risks derived from hydraulic actions including scour, uplift, drag, debris impact, deck displacement, and other consequences that can lead to a loss in the load carrying capacity of a bridge. In the UK, the CS469 (Management of scour and other hydraulic actions at highway structures) is the standard for the assessment of hydraulic actions to highway bridges. The methodology in CS469 for the calculation of the hydraulic characteristics of the flow at critical cross‐sections within the channel and the bridge crossing, although simplistic by design to minimize computational effort, is intrinsically inaccurate since it makes use of unrealistic (i.e., non‐physically based) approximations. This results in estimations of risk and vulnerability levels that could include high levels of uncertainty. In this paper, we propose to bypass these approximated hydraulic calculations by harnessing the computational power of 2D hydraulic models, which would not require any additional field data collection than needed for the original CS469 method. We recommend a fully 2D HEC‐RAS model with the inclusion of bridges as 1D elements within the flow areas and only requiring publicly available data or data obtained from existing assessments in order to future‐proof the approaches and adhere to an open‐source/open‐access philosophy, but also imposing only a marginal increase in cost for bridge management teams. Results from the two models—2D HEC‐RAS and the existing approach in CS469, are compared for a number of real‐world bridges. The comparisons show that the estimations by HEC‐RAS are substantially higher for water depth (up to 138%) and lower for flow velocity (down by 58%). When these values are applied to the estimation of hydraulic vulnerability and scour risk, the differences are significant. Scour depths with the use of HEC‐RAS models are typically much lower (up to 3.9 m, and on average 1.7 m) than with simplified hydraulic equations, and this translates into lower (yet, more appropriate) scour risk levels. Hydraulic vulnerability to submergence of the assessed bridges is also assessed very differently, typically higher by the 2D model method. Overall, the results show that 2D numerical hydraulic simulations present a much more accurate estimation than existing methods, better balancing risks deriving from scour and hydrodynamic actions and with comparable effort and data requirements. The model displays consistency across an exhaustive set of simulations for a range of variables and bridges, showing limited variability and proneness to errors, whilst values estimated by CS469 are in most cases significantly different. Future versions of CS469 and similar documents should prioritize this methodology to provide a more accurate and realistic risk estimation.

Wayne Carpenter, Bradley Goodwiller, Daniel Wren

The National Center for Physical Acoustics (NCPA) at The University of Mississippi has developed a single-frequency acoustic attenuation system (SFAAS) to monitor the concentration of suspended fine sediments in rivers and streams. The system was operated in the Goodwin Creek Watershed in Panola County, Mississippi, USA, from November 2019 to February 2023. The system collected data when the stream stage was above 0.3 m, and physical pump samples were collected concomitantly to provide calibration data. A subset of the data, comprising 14 storm events recorded over the multiyear deployment, will be presented here to demonstrate the operation of the SFAAS and its potential to aid in hydrologic research. SFAAS was able to provide high-resolution fine sediment concentration data with a stable calibration relationship for a given hardware configuration. The data were used to investigate the behavior of fine sediment concentrations in the watershed, including hysteresis in the relationship between flow rates and sediment concentrations during streamflow hydrographs and sediment rating curves that relate stream depth to transport rates.

Joe Forbis, Cuong Ly

Abstract The US Army Corps of Engineers (USACE) prescribes flood control operations for reservoirs it regulates in watershed‐specific water control manuals (WCMs), which can be decades‐old and may not capture changed conditions in the watersheds or include the benefit of state‐of‐the‐science weather and streamflow prediction. Considering the specific characteristics of a reservoir, forecast‐informed reservoir operations (FIRO) may be used to enhance flood risk reduction, improve water availability, and achieve other benefits. The first FIRO pilot project at Lake Mendocino in California focused on determining if water supply reliability could be improved using FIRO without increasing flood risk. The final report concluded that FIRO concepts could indeed improve water supply reliability while enhancing flood risk reduction. Subsequently, USACE chose additional reservoir systems in California with different characteristics as additional pilot study locations to further investigate FIRO concepts. These successful FIRO efforts have provided justification to continue its expansion beyond the initial pilot sites. The lessons learned from the FIRO pilot projects are being used to inform the development of the FIRO Screening Process, a screening level framework intended to scale up the implementation of FIRO. The lessons learned could support FIRO implementation at suitable USACE reservoirs by updating WCMs.

Hongjun Joo, Wonyoung Choi, Chansoo Jeon

Abstract Floods are the most frequent types of natural disasters. From the perspective of disaster management, indicators associated with floods are important for accurate flood risk assessment. However, the application of all indicators related to flood risk assessment decreases the evaluation efficiency, because the definitions of the indicators may overlap. Moreover, the volume of data required for collection and evaluation is significantly large, making the evaluation practically impossible. Thus, a scientific and objective method to select indicators for flood risk assessment based on the entropy theory was developed herein. First, the existing 28 assessment indicators were analyzed and probability‐based data were constructed for each indicator considering 28 districts in a midwestern region of Korea. The information quantity for each indicator was then obtained using marginal entropy and mutual information generated in the entropy theory. Next, the total information quantity based on the numbers of combination of indicators was derived by considering the information quantity for each indicator and the overlapping mutual information between the indicators. The maximum amount of information (161.55) was obtained by combining 18 out of the 28 flood risk indicators. The selected 18 indicators reflected regional characteristics better than those used in the existing method, demonstrating that the flood risk of the target area could be adequately assessed.

Renato Amorim, Gabriele Villarini

Abstract The detection of nonstationarities in partial duration time series (PDS) depends on several factors, including the length of the time series, the selected statistical test, and the heaviness of the tail of the distribution. Because of the more limited attention received in the literature when compared to the trend detection on block maxima variables, we perform a Monte Carlo simulation study to evaluate the performance of different approaches: Spearman's rho, Mann–Kendall, ordinary least squares (OLS), Sen's slope estimator (SEN), and the nonstationary generalized Pareto distribution fit to identify the presence of trends in PDS records characterized by different sample sizes (n), shape parameter (ξ) and degrees of nonstationarity. The results point to a power gain for all tests by increasing n and the degree of nonstationarity and by reducing ξ. The use of a nonparametric test is recommended in samples with a high positive skew. Furthermore, the use of sampling rates greater than one to increase the PDS sample size is encouraged, especially when dealing with small records. The use of SEN to estimate the magnitude of a trend is preferable over OLS due to its slightly smaller probability of occurrence of type S error when ξ is positive.

Nanée Chahinian, Matias Alcoba, Ndji dit Jacques Dembélé et al.

Abstract Devastating floods have plagued many West African cities in the past decades. In an attempt to reduce flood damage in Bamako (Mali), an early warning system (EWS) demonstrator (Raincell App) was developed for flash floods. On 16 May 2019, while the demonstrator was partially operational, an intense rainfall event led to devastating floods. We carried out an experience feedback on this flood event by comparing EWS simulations to the results of a field survey. Given the synoptic situation and the rapid development pattern of the storm, none of the global forecasting systems were able to foresee its occurrence and magnitude. The hydrological model developed as part of the demonstrator correctly identified most of the locations where overbank flow occurred. In the absence of data, the predicted discharge and volume values could not be validated. However, they are realistic based on the water levels reported in the Post‐Disaster Needs Assessment report. It would be advisable to couple it to a two‐dimensional hydraulic model and add discharge and water level monitoring to the already existing rainfall surveillance scheme to further improve the system's performance. Increasing the local population's awareness of the dangers of clogged waterways is also mandatory.

Chrissy Mitchell

Peter R. Davids, Sally Priest, Thomas Hartmann

Abstract This paper investigates the role of flood risk experts in supporting homeowners to implement property‐level flood risk adaption (PLFRA). Homeowners can reduce their flood risks by implementing PLFRA. However, oftentimes they need advice on what sort of and how to implement PLFRA. This means that tailored experts advice is necessary to inform homeowners on such measures. But experience shows that mere information is often insufficient to motivate homeowners to realise measures. This contribution explores the reasons for the ineffectiveness of expert advice by investigating how expert advice responds to homeowners' rationalities. Based on a case study from Flanders, Belgium, this paper reveals how the relation between experts and homeowners differs related to different rationalities of homeowners. The paper uses Cultural Theory to discuss strategies on how experts, providing advice on property‐level risk adaption, could move beyond engineering skills by also using risk communication skills in order to involve homeowners in flood risk governance.

امید اسدی نلیوان, علیرضا رابط, فرزانه وکیلی تجره et al.

مقدمهفرسایش خندقی یکی از انواع فرسایش آبی است که سهم زیادی در تخریب اراضی دارد و به‌­عنوان یکی از مهمترین مخاطرات محیطی در جهان و به­‌خصوص در ایران شناخته شده است. در سال­‌های اخیر، فن‌های یادگیری ماشینی و سامانه اطلاعات جغرافیایی در زمینه تعیین مناطق حساس به فرسایش خندقی دارای کارایی بالایی بوده­اند و باعث افزایش دقت و سرعت در زمینه ارزیابی، پتانسیل فرسایش خندقی شده‌­اند که این فن‌ها در تعیین عوامل موثر بر فرسایش خندقی نیز موثر بوده‌­اند. اراضی لسی استان گلستان به­‌دلیل عمق کافی و دانه‌­بندی تقریبا یکنواخت سیلتی، استفاده مفرط، کشت در اراضی شیب­دار و مدیریت غلط اراضی، فرسایش‌­پذیری آبی بیشتری دارند، به طوری که همه انواع فرسایش را در این مناطق می­‌توان مشاهده کرد. متداول‌­ترین نوع فرسایش در این مناطق، فرسایش خندقی است. حوزه آبخیز مورد مطالعه در استان گلستان، با افزایش زمین­‌های دیم و رها شده، تغییر کاربری اراضی، حضور دام مازاد در جنگل‌­ها و همچنین، افزایش جمعیت روبه­‌رو است. لذا، این حوضه با افزایش حساسیت فرسایش خندقی مواجه است و باید مناطق دارای پتانسیل فرسایش خندقی شناسایی و مدیریت شوند. مواد و روش‌هاحوزه آبخیز مورد مطالعه با مساحت 222 هزار هکتار و دامنه ارتفاعی 58 تا 2168 متر، در شمال شرقی استان گلستان قرار دارد. میانگین بارندگی حوضه بین 224 تا 736 میلی­متر است. در این پژوهش، ابتدا موقعیت خندق­‌ها از اداره کل منابع طبیعی و آبخیزداری استان گلستان دریافت شد. سپس، از مجموع 1127 موقعیت خندق، به‌­صورت تصادفی 70 درصد به­‌عنوان داده‌­های آموزش و 30 درصد به­‌عنوان داده­‌های اعتبارسنجی طبقه‌­بندی شدند. به‌منظور تعیین متغیرهای موثر در حساسیت فرسایش خندقی، 14 عامل شناسایی شد و در مرحله بعد تست هم­خطی بین متغیرها با استفاده از نرم‌­افزار SPSS انجام شد. با استفاده از شاخص­‌های ضریب تحمل و عامل تورم واریانس در صورت وجود هم­خطی بین متغیرها از روند مدلسازی حذف شدند. با توجه به اهمیت نقشه مدل رقومی ارتفاع و کاربرد آن در تهیه عوامل مختلف پژوهش حاضر، مدل رقومی ارتفاع (با اندازه سلول 12.5 متر) با استفاده از تصاویر ماهواره ALOS تهیه شد. لایه­‌های شیب و جهت شیب با استفاده از مدل رقومی ارتفاع و به‌­ترتیب از توابع Slope و Aspect تهیه شده‌­اند. شاخص طول شیب در نرم‌­افزار SAGA GIS، لایه­‌های فاصله از آبراهه بر اساس نقشه آبراهه­‌ها (استخراج از نرم‌­افزار SAGA GIS) و فاصله از جاده بر اساس جاده‌­های موجود و با استفاده از تابع فاصله اقلیدسی در نرم‌­افزار ArcGIS تهیه شدند. لایه‌­های تراکم آبراهه و تراکم جاده، بر اساس نقشه آبراهه‌­ها و جاده­‌های موجود در منطقه و با استفاده از تابع Line Density در نرم‌­افزار ArcGIS به­دست آمدند. لایه سنگ­‌شناسی از نقشه زمین‌شناسی منطقه (مقیاس 1:100000) استخراج شده است و لایه کاربری اراضی از اداره کل منابع طبیعی و آبخیزداری استان گلستان دریافت شد. نقشه بارندگی با استفاده از اطلاعات 35 ایستگاه باران­‌سنجی تهیه شده است. ابتدا، میانگین بارندگی 26 ساله (دوره آماری مشترک) برای هر ایستگاه محاسبه شد و سپس، با استفاده از روش کریجینگ جهانی (به‌­دلیل کمترین میزان RMSE) در نرم‌­افزار ArcGIS پهنه­‌بندی بارندگی انجام گرفت. لایه شاخص موقعیت توپوگرافیک، با استفاده از مدل رقومی ارتفاع و با کمک نرم‌افزار SAGA GIS تهیه شد. به‌منظور ارزیابی مدل‌­ها، از منحنی تشخیص عملکرد نسبی (ROC) جهت قدرت پیش­بینی مدل­‌ها استفاده شد. نتایج و بحثنتایج نشان داد که بین متغیرها هم­خطی وجود ندارد و لذا، کلیه متغیرها در روند مدلسازی مورد استفاده قرار گرفتند. رابطه بین فرسایش خندقی و ارتفاع نشان داد که ارتفاعات پایین­تر حساسیت بیشتری نسبت به ارتفاعات بالاتر دارند و نزدیک به آبراهه­ها حساسیت فرسایش خندقی بیشتر است. نتایج نشان داد که با افزایش تراکم زهکشی، حساسیت فرسایش خندقی افزایش پیدا می­کند. همچنین، پادگانه­های قدیمی، شیل و لس­ها بیشترین تاثیر را بر حساسیت فرسایش خندقی دارند. نتایج نشان­دهنده کاهش حساسیت فرسایش خندقی با کاهش شاخص HAND است. در واقع این نتیجه بیانگر این است که در مناطقی که میزان سطوح اشباع در سطح حوزه آبخیز افزایش می­یابد، احتمال وقوع و حساسیت فرسایش خندقی افزایش پیدا می­کند. نتایج نشان داد که در میان انواع کاربری­ها، مسیل­ها، مراتع فقیر و کاربری کشاورزی، دارای بیشترین حساسیت فرسایش خندقی هستند. این در حالی است که مناطق جنگلی دارای کمترین میزان حساسیت به این فرسایش بوده­اند. نتایج نشان داد که در دامنه بارندگی 220 تا 420 میلی­متر، احتمال رخداد فرسایش خندقی افزایش پیدا کرده است و از دامنه 420 تا 500 میلی­متر، بالاترین میزان حساسیت را نشان داده است و با افزایش بارندگی از 500 میلی­متر، حساسیت فرسایش خندقی کاهش یافته است. از دلایل کاهش حساسیت فرسایش خندقی در بارندگی­های بالاتر می­توان به افزایش پوشش گیاهی و ایجاد شرایط مناسب برای زمین­لغزش­ها اشاره کرد. نتایج نشان داد که عمق دره تا 235 متر، باعث افزایش احتمال فرسایش خندقی شده است و از 235 متر به بالا، باعث کاهش احتمال رخداد فرسایش شده است. نتایج نشان داد که نزدیک به جاده­ها میزان حساسیت فرسایش خندقی افزایش پیدا می­کند و این مورد اثرات جاده­سازی و تشدید شرایط برای فرسایش خندقی را نشان می­دهد. نتیجه‌گیریاین پژوهش با هدف تعیین عوامل موثر بر فرسایش خندقی و پهنه­بندی توزیع مکانی آن در شمال شرق استان گلستان انجام شد. در این پژوهش، با در نظر گرفتن 14 عامل مهم و با استفاده از مدل­های جنگل تصادفی، شبکه عصبی مصنوعی و درخت رگرسیون و طبقه­بندی، نقشه حساسیت وقوع فرسایش خندقی تهیه شد. با توجه به این­که شناسایی مناطق دارای حساسیت فرسایش خندقی مبتنی بر روش­های سنتی و نظرات کارشناسی از دقت قابل قبولی برخوردار نیست، استفاده از روش­های نوین یادگیری ماشینی امری ضروری است. نتایج نشان داد که عوامل فاصله از جاده و کاربری اراضی از مهمترین عوامل تاثیرگذار بر حساسیت فرسایش خندقی هستند که مدیریت کاربری اراضی را از سوی انسان می‌طلبد. منحنی ROC، نشان داد که دقت مدل­ها در برآورد مناطق دارای حساسیت فرسایش خندقی در مرحله آزمون عالی (ANN)، و در مرحله آزمون و اعتبارسنجی خیلی خوب (RF  و CART) بوده است که به معنای عملکرد عالی مدل­ها است.

Yang Ma, Yantao Cui, Huagao Tan et al.

Abstract Accompanying its rapid urban development, prevalent urban flooding incidents have been occurring in China in the past two decades with increasing frequency. Through a comparison with generally accepted urban flooding management practices, we (the authors) identified that a lack of surface water runoff management considerations (i.e., missing a major drainage system in urban stormwater system) and inadequate local mitigation are the primary causes of urban flooding problems in China, which in turn is rooted in the planning stage of a city's development. Following identification of the primary causes for the problems, we propose the development of master drainage plans (MDPs) for the concerned cities or regions as the first effective step to mitigate the serious urban flooding problems facing many cities today. An MDP would provide necessary elements to develop a major drainage system for the city's stormwater system and allow for an accurate calculation of parameters necessary for installation of adequate local mitigations. Lessons learned in this study should be useful for China's administrative agencies and professionals while they try to find solutions to their urban flooding problems and beneficial to other nations facing rapid urban development in the future or with existing urban flooding threats.

Zohreh Masoumi

Abstract In urban areas, flood susceptibility assessment is of special importance because of the high settlement population, properties, and infrastructures. Geospatial information science (GIS) provides a tool for investigating flood susceptibility based on several aspects including economic damages and critical infrastructures in cities. This study aims to provide a tool based on GIS analyses to support decision‐makers in identifying flood hazards in urban areas, in which previous flood data, flood causative factors, and urban infrastructure data are not adequately available. To assess flood susceptibility in the study area, the related spatial high‐resolution data were produced. Then, flood zones were estimated for different recurrence intervals using meteorological data. Finally, susceptibility was assessed in urban areas for different urban infrastructures using GIS modeling. The model was designed based on the assumption that any critical urban infrastructure, such as power towers, was affected by flood zones and, in addition to flooding, could cause hazards by itself. Moreover, five scenarios were defined to calculate susceptibility when in the problematic locations of the floodway. DoAsb Floodway was chosen as a case study located in Zanjan city, northwest of Iran. The results indicated the high‐susceptible areas around the floodway. Moreover, the flood susceptibility level for each urban infrastructure in the study area was calculated and classified into five classes from low susceptible to very high susceptible. Also, the results of the five scenarios showed if some parts of the floodway had problems, the susceptibility rate would be high. The generated flood susceptibility maps of this model can be used to plan suitable programs in order to avoid flood damage and ensure public safety.

Leon Maximilian Netzel, Sonja Heldt, Steven Engler et al.

Abstract Heavy precipitation events are expected to increase in frequency and intensity in many parts of Europe as a result of climate change. These events can affect regions located far from rivers that have never been affected before. As warning times are short, there are hardly any effective emergency measures to mitigate the severe damage caused by pluvial floods. Therefore, long‐term mitigation measures are necessary for sustainable urban flood management. However, people first need to realise their personal risk in order to become active and take private precautionary measures. To get a better understanding of the processes underlying public risk perception of pluvial floods, a questionnaire‐based telephone survey was conducted analysing two case studies in western Germany. Key findings reveal that risk perceptions need to be distinguished between personal and global perception. Personal risk perception was low among the participants, while their global risk perception was far higher. The determinants of global and personal risk perception on pluvial flooding were identified. The study also showed that mitigation behaviour is influenced by personal risk perception, knowledge, education, and housing conditions. These determinants should receive attention when future risk communication and flood management strategies are developed.

Eduardo Martínez‐Gomariz, Beniamino Russo, Manuel Gómez et al.

Abstract Before the solid waste is dumped in landfills, the collection process for large Spanish cities starts from a regular collection of household waste municipal service which is carried out through street containers. When an urban flood occurs those containers may lose their stability, thereby allowing debris (i.e., solid waste contained) and leachate to escape from the container and contaminate the flood water. Moreover, once a container loses its stability it can further constrict a narrow street and increase flooding, thereby creating a closed basin with no outlet for runoff and exacerbating the effects of flooding. Therefore, the waste containers stability when exposed to flooding is definitely an environmental, safety and health concern to be addressed. In this research stability functions for waste containers exposed to urban floods have been derived. These thresholds have been employed to analyse the containers' potential behaviour during floods in Barcelona. In order to validate the model a historical rainfall has been modelled and low‐return‐period design storms (i.e., 1, 5, and 10 years) have been used to assess the containers vulnerability against floods for frequent rainfall events. Once the number of potentially unstable containers has been estimated, an adaptation measure has been proposed in order to increase the resilience of waste sector against urban floods in Barcelona.

Álvaro Enríquez‐de‐Salamanca

Abstract Heavy rainfall causes many watercourses to overflow. In these circumstances, crossing by car even on a road, can be extremely dangerous; however, dozens of drivers are swept away every year in their vehicles. This paper analyses this type of accident in Spain between 2008 and 2018, recording the date, location, number of victims, age and gender, and rainfall during the event. The results show that 125 accidents occurred with 200 victims including 45 fatalities. Most accidents occurred in E, S and SE Spain, where the rainfall irregularity is greater, during December, October and March, although fatalities were concentrated in September and October. Among the victims male drivers dominated, with an average age of 52 years. The main cause of these accidents was the drivers' behaviour due to: underestimating risk, overconfidence, overvaluation of their driving skills, an excess of trust in the authorities, ignorance about vehicle drag and buoyancy risks, and, social pressure. To reduce these risks, it is necessary to increase adaptation and protection measures on roads, but above all, a change in drivers' behaviour to stop them trying to cross‐flooded rivers.