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

Elena Macdonald, Bruno Merz, Jeroen C. J. H. Aerts et al.

ABSTRACT Climate change, with its links to an intensified water cycle, heavier rainfall, and potentially higher flood peaks, raises concerns about the adequacy of current flood risk management. The devastating July 2021 floods in western Europe underscored these concerns, highlighting the need for transboundary cooperation and shared expertise in adapting flood risk management to climate change. However, uncertainty in future flood projections presents challenges for agencies and governments in upgrading existing measures or designing new ones. Here, we review how climate change information is integrated into flood risk management, focusing on flood design values and flood hazard and risk maps. Focusing on Germany, The Netherlands, Belgium, and Luxembourg—the countries significantly impacted by the 2021 floods—we examine regional practices, as flood risk management is often organized at the sub‐national level. Specifically, we assess whether regions have published flood policy papers, developed future flooding scenarios under climate change, and translated these scenarios to flood hazard and risk maps and the design of protection measures. Our findings reveal that all 20 regions have adaptation plans addressing climate change and almost all regions have developed future flood projections but only three incorporate them into climate‐adjusted design values and only one provides flood hazard and risk maps under future climate scenarios. Assessments of the future climate vary widely. For example, Flanders in Belgium uses a full range of CMIP5 emission scenarios (RCP2.6 to RCP8.5), while Baden‐Württemberg and Bavaria in Germany rely on the worst‐case scenario (RCP8.5). Similarly, The Netherlands adopts an approach using 33 global climate models and a dynamic adaptation pathway framework to address uncertainties, whereas Saxony in Germany argues that the spread of projections is too large to derive design values and emphasizes the need for standardized scenarios and methods. In summary, our synthesis highlights substantial gaps in climate‐proofing flood risk management and significant regional variation in approaches. Enhanced and faster cross‐border learning could improve the effectiveness of climate‐informed flood risk management.

Silvia Di Francesco, Sara Venturi, Stefano Casadei et al.

ABSTRACT The work proposes the development of a Lattice Boltzmann (LB) Cascaded collision operator (CO) model with two unexplored main purposes: reproducing the dynamics of multilayer shallow water flows and modeling urban floods with a porosity approach. The Cascaded CO has been already proved to enhance accuracy and stability in low‐viscosity flows, like water, outperforming other mesoscopic models. Its adaptation to a multilayer model allows capturing vertical variations in hydrodynamic quantities of large‐scale geophysical flows. To simulate n‐layer flow dynamics, the model CaLB‐N solves n shallow water equations, one for each layer, with coupling terms representing the mutual interactions between layers. Capturing localized flow features in large scale flood events is still a challenge: in complex morphology like urban areas, the dimension of the city dominion is many orders of magnitude larger than buildings, thus they can hardly be taken into account. The introduction of a new sub grid porosity‐based LB model (CaLB‐P) allows facing this issue, considering in a specific source term the portion of a computational cell that is available for flow. The model is implemented in C and parallelized to achieve computational speeds suitable for large‐scale applications. This optimization allows for high‐resolution simulations while substantially reducing processing time. The applicability of the suggested model for hydraulic engineering is explored, paving the way for new approaches to realistically model complex water flows.

Weixing Zhou, Zhaohua Sun, Zhonghua Yang et al.

Confluence‐induced river discontinuities pose several challenges for flood control, navigation, and maintenance of ecological integrity. River‐connected lakes in lowland regions represent a unique type of confluence, fulfilling significant floodplain functions in fluvial processes and forms of main streams, yet they remain insufficiently studied. This study utilized Dongting Lake in the Middle Yangtze River as a representative case to examine the confluence effects of lake‐type tributary on the fluvial processes of the main stream and to identify key driving factors. The findings revealed that during the equilibrium period, both the flow frequency curves and sediment‐transport rating curves exhibited segmentation characteristics due to the floodplain functions of river‐lake system. The confluence effects of the lake amplified the segmentation behaviors across spatial scales, which inherently depended on the river‐lake flow combination. Following the Three Gorges Reservoir impoundment, alterations in the confluence effects of the lake led to recent abnormal local erosion‐deposition adjustments under sediment subsaturation conditions, whereas upstream reservoir regulation dominated a long‐term reduction in channel‐forming discharge with a channel shrinkage trend downstream of the confluence. Despite the altered water‐sediment regimes, tributary inflow qualitatively remains a critical factor influencing the discontinuity of fluvial processes in the main stream. Our research demonstrated that the hydrological characteristics of confluence, rather than sediment transport, significantly influence the fluvial processes of lowland alluvial river. This insight enhances our understanding of the evolutionary mechanisms of large alluvial rivers with complex river‐lake relationships and offers important implications for the management of water resource systems.

M. O’Callaghan, J. D. del Hoyo, B. Finch et al.

Experimental floods have been proposed as a measure to mitigate effects of river flow regulation, primarily vegetation encroachment, streambed colmation, and loss of bed and channel mobility. In this study, we investigated the short‐ and long‐term biogeomorphic effects of an experimental flood programme conducted in the Spöl River (Swiss Alps) since 2000. Based on a GIS analysis of orthoimages between 1991 and 2023, we characterize the past and current state of fluvial biogeomorphic succession. From field surveys, we describe the current distribution of riparian vegetation in the lower Spöl. Lastly, we investigate the impact of experimental floods on riparian trees through dendrogeomorphological indicators. Over the study period, we identified a significant increase in active channel width and an associated reduction of vegetation encroachment. However, no significant colonization of gravel bars by pioneer species was observed. Tree‐ring widths showed a general decrease in riparian tree growth since the beginning of the experimental flood programme. We show that this apparent control of hydrogeomorphic processes on biogeomorphology and the corresponding absence of vegetation succession patterns is due to high aggradation rates of sediment delivered by an unregulated tributary. We discuss the implications of these findings for future management of the river and experimental flood programme and raise caveats regarding the future developments of river morphology in the lower Spöl.

B. Finch, J. Hoyo, J. Aarnink et al.

While instream large wood is recognized as vital for healthy river ecosystems, the wood regime remains less understood compared to flow and sediment regimes, primarily due to limited monitoring. Most existing research focuses on unregulated rivers, leaving knowledge gaps in regulated systems. This study addresses that by quantifying the wood regime in the Spöl River, a partially regulated alpine river affected by two dams. Despite regulation, the Spöl still receives sediment and wood from unregulated tributaries and benefits from an experimental flood (e‐flood) program initiated in 2000 to mitigate dam impacts. By July 2023, 23 e‐floods had been released from the Ova Spin Dam. Between 2018 and 2023, five of these were monitored to assess wood entrainment, mobility, and deposition. The study explored how much wood moved, where it was deposited, and what factors controlled its transport. Wood movement, measured by number, volume, and distance, was related to e‐flood hydrograph characteristics. On average, less than 30% of wood was mobilized per flood, and long‐distance transport was limited (mean <300 m), aligning with findings from unregulated rivers. Results showed that flood duration, especially the rising limb duration, better explained wood mobility than flood magnitude. This monitoring effort offers rare insights into the interactions between flow, sediment, and wood in a regulated alpine river, and informs the design and effectiveness of e‐flood programs.

Jan Brabec, Jan Macháč, András Kis et al.

Abstract Flooding poses a significant and recurring threat in numerous regions. The adverse impacts of flooding can be mitigated through risk sharing, such as insurance or risk reduction. However, insurance might not be accessible in underdeveloped markets or in instances where floods are too frequent. Similarly, the necessary funding or land for structural measures might not be available. Alternatively, measures could be implemented on private land, either through individual initiatives or as part of a coordinated effort. This approach was explored in the flood‐prone regions of Albania and North Macedonia. A survey conducted among 124 farmers revealed that 73% of them are willing to allocate land for flood mitigation, provided they receive adequate compensation. Furthermore, certain factors increase farmers' willingness to cooperate. A logit model indicated a positive correlation between expectations of future floods (increased severity and frequency), receipt of ex‐ante financial support, positive perception of the effectiveness of agricultural flood mitigation measures, and age. Those who view flood protection as personal responsibility and those more inclined to pay for flood insurance are less likely to cooperate. The findings could be utilized to identify farmers who are likely to contribute to establishing a coordinated effort on a stable basis.

Erika R. Meléndez‐Landaverde, Daniel Sempere‐Torres

Abstract People‐centred early warning systems must ensure that their warnings are timely, actionable and get to the largest number of exposed individuals in the shortest time possible. Due to the increased access to high‐bandwidth communication, mobile applications have become a valuable complement to traditional sources of emergency information. However, there is limited research on how useful end‐users perceive these apps and their functionalities in the context of flood emergencies. This research presents the first online user experience evaluation of the A4alerts, a crisis app developed to disseminate the flood warnings triggered by the operational impact‐based early warning system in Catalonia, Spain. Following an interactive experiment using the A4alerts app to access emergency information within real‐based flood scenarios, participants were prompted to measure their experience using statements linked to criteria on usefulness, functional appropriateness, and adoption. The evaluation results suggest that sampled participants considered the A4alerts a useful communication tool to support end‐users and their emergency actions. In particular, the local impact‐based flood warnings, regional official warnings and self‐protection action checklist were ranked as the most useful functionalities implemented within the app. These findings justify future iterations of the A4alerts for supporting the rapid dissemination of emergency information and helping communities reduce the impacts of flood events.

Ya Zhou, Lei Huang, Liangwen Huang et al.

Global-scale changes in precipitation and temperature lead to regional variations in the hydrologic cycle. Understanding the impacts of climate change on discharge and sediment processes is crucial for effective watershed management, especially in alpine regions. A hydrologic modeling framework was established for the Yarlung Tsangpo River (YTR) watershed, the largest and longest river system on the Tibetan Plateau, which integrates the Soil and Water Assessment Tool (SWAT) with global climate models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6). The results highlight the importance of temperature in influencing hydrological elements during snowmelt periods in the northeastern and western parts of the YTR basin and precipitation across the entire basin during rainy periods. Compared with discharge, sediment flux has been more sensitive to climate change over the past four decades. The annual mean discharge at the downstream station is projected to decrease by −3.60% ± 2.68% in the near-term period (2025–2035) but increases by 4.18% ± 3.30% in the mid-term period (2040–2050) relative to the baseline value of 2000–2014. Moreover, the annual mean sediment flux is expected to change by −1.06% ± 2.98% in the near-term period and by 8.30% ± 3.65% in the mid-term period. These results will enhance adaptive management and policy-making for alpine regions.

Kazuki Yamanoi, Satoru Oishi, Kenji Kawaike

ABSTRACT Debris‐flow affected area is typically predicted using runout simulations, often estimating the hydrograph from rainfall conditions. However, rainfall is rarely considered when predicting initiation locations, which influence the occurrence number and location. This study proposes a hybrid method combining statistical source‐location prediction based on rainfall conditions and runout simulations inputting the predicted source locations. First, logistic regression is used to predict the spatial probability of debris‐flow initiation with rainfall as an input. Next, Monte Carlo simulation based on the initiation location generated from the rainfall‐based probability yields the spatial distribution of the debris‐flow hit probability. Simulation parameters are systematically determined in advance based on topographic change obtained via aerial LiDAR observations. This method was successfully employed to estimate the spatial distribution of the debris‐flow hit probability at 1‐m resolution for a debris‐flow disaster that occurred in Hiroshima prefecture, Japan, using rainfall data obtained by radar. The simulation time indicated that hit probability can be issued prior to the event for early warning, owing to the adequate lead time of rainfall forecasts and recent developments in computational technology. The hit probability obtained in this study can be also applied to risk quantification based on rainfall conditions.

Faisal Ismail, Atiya Farag, Soghra Haq

Yuan He, Zihao Fan, Wei Zhao et al.

Vegetation litter is effective in mitigating surface soil erosion caused by rainfall and runoff. Studying the runoff, sediment yield, and hydrodynamic characteristics of the soil covered by vegetation litter cover is crucial to understanding how vegetation litter cover affects soil erosion. To assess the impacts of different types of vegetation litter on soil erosion in the Taiyi Mountain area of northern China, Quercus acutissima Carruth. (QAC), Pinus densiflora Siebold &amp; Zucc. (PDS), Vitex negundo var. heterophylla Rehd. (VNH), and Themeda japonica Willd. (TJW) litter covered soil were the research subjects, and no-litter covered soil was used as a control check (CK). The process of erosion of soil covered by different vegetation litter under different rainfall intensities (50, 75, and 100 mm/h) with 60 min of rainfall was studied. It was found that compared with CK, the runoff and sediment yield rates of litter-covered soil decreased by 18.95%–44.15% and 21.42%–60.16%, respectively. In terms of the effect on reducing the runoff and sediment yield rate, the performance is QAC > PDS > VNH > TJW. Under varying rainfall intensities, the patterns of runoff and sediment yield fluctuate as rainfall duration increases. Likewise, with the increase in rainfall intensity, the runoff yield rate and sediment yield rate also show an increasing trend. The runoff yield rate was increased by 3.21 and 1.49 times under 100 mm/h compared with 50 and 75 mm/h, respectively. Additionally, there were 16.56 and 1.44 times, respectively, and increases in the sediment yield rate. Hydrodynamically, litter cover increases the Darcy-Weisbach friction coefficient by 1.49–11.15 times, increases the shear stress threshold for initiating soil erosion by about 6.67%–38.01%. This further led to a reduction in the runoff flow velocity and stream power, by approximately 14.87%–67.26% and 7.38%–61.54%, respectively, thereby reducing the degree of soil erosion. The current research demonstrates that the characteristics of soil erosion and sediment yield under vegetation litter cover can be more accurately described by the stream power among the hydrodynamic parameters.

Hyeonjin Choi, Hyuna Woo, Hyungon Ryu et al.

ABSTRACT Urban flood forecasting benefits from high‐resolution inundation maps, but fine‐grid hydrodynamic simulations are computationally costly. We compared three CNN–based super–resolution (SR) models, ResUNet, EDSR, and RCAN, for downscaling physics–based simulations in downtown Portland, Oregon, using paired flood maps at 1 m (HR) and both 4 and 8 m (LR). Performance was assessed using image level metrics (PSNR, SSIM) and flood specific indicators: CSI for flood extent, RMSE for water depth accuracy, and a depth–based severity classification. At 4× upscaling, all SR models outperformed the LR baseline; RCAN performed best (PSNR +57%, SSIM +31%, RMSE −73%, CSI +53%), followed by EDSR (PSNR +50%, SSIM +30%, RMSE −64%, CSI +45%) and ResUNet (RMSE −55%, CSI +40%). Analysis of class–wise recall showed RCAN leading for non–flood (98.06%, +6.59 pp) and severe flood (96.48%, +16.90 pp), while EDSR led for mild flood class (97.95%, +6.49 pp). Errors were most pronounced along wet–dry boundaries and in complex urban geometries, where RCAN and EDSR reduced error magnitude more effectively than ResUNet. Models with larger numbers of parameters required longer training times. Furthermore, the computational cost further increased with more training epochs and especially at 4× upscaling relative to 8×, reflecting differences in model complexity and scaling configuration. Taken together, these findings support SR as a practical complement to physics–based modeling for real time forecasting and planning, while also providing guidance for selecting architectures under varying computational budgets.

Laurence Girolami, Stéphane Bonelli, Jean‐Michel Carozza et al.

ABSTRACT The subsoils of river dikes are often composed of highly permeable and low‐density river sediments. Thus, erosion signatures (leaks, sand boils, sinkholes) can appear in the protected floodplain during floods, highlighting the development of hydromorphodynamic phenomena below the surface, which may harm the safety of the dike system. A multiscale methodology is deployed to understand and analyze the influence of floodplain architecture in terms of geological formations on the appearance of local erosion signatures. Particular attention is paid to the morphology of paleovalleys and paleochannels in order to image the subsurface in terms of substrate types and interfaces using geophysical methods. This information makes it possible to propose internal erosion scenarios. Application to a study area in the South of France (the Agly dike system) leads to new results. The classical backward erosion piping scheme is not relevant to explain the observed sand boils, as they are mainly caused by the suffusion‐type internal erosion process. Suffusion and contact erosion appear to be the origin of sinkholes. The distribution of these signatures appears to be directly related to the shape and dimensions of the paleovalley and paleochannels, as well as to the presence of a low‐permeability topsoil.

Yize Chen, Baosen Zhang

Recent boom in foundation models and AI computing have raised growing concerns on the power and energy trajectories of large-scale data centers. This paper focuses on the voltage issues caused by volatile and intensity of data center power demand, which also aligns with recent observations of more frequent voltage disturbances in power grids. To address these data center integration challenges, we propose a dynamic voltage control scheme by harnessing data center's load regulation capabilities. By taking local voltage measurements and adjusting power injections at each data center buses through the dynamic voltage and frequency scaling (DVFS) scheme, we are able to maintain safe voltage magnitude in a distributed fashion with higher data center computing load. Simulations using real large language model (LLM) inference load validate the effectiveness of our proposed mechanism. Both the LLM power data and proposed control scheme are open sourced.

مجید محمدی, مجتبی امیری

مقدمهفعالیت‌های انسانی از مهم‌ترین دلایل تغییرات محیطی بوده و انسان‌ها نقش اساسی در گرمایش زمین، تخریب زمین، آلودگی آب و خاک، بالا رفتن سطح آب دریاها، تخریب لایه ازن، جنگل‌زدایی شدید و اسیدی کردن اقیانوس‌ها دارند. در مقیاس جهانی، تخریب و فرسایش یکی از مهم‌ترین پدیده‌های طبیعی است که مناظر را تغییر می‌دهد. فرسایش خاک اثرات درون‌منطقه‌ای و برون‌منطقه‌ای فراوانی را به‌همراه دارد. فرسایش و هدررفت خاک معمولاً در مناطق شیب‌دار اتفاق می‌افتد اما شدت وقوع آن به عامل‌های محیط‌زیستی از قبیل میزان شیب، ویژگی‌های زمین‌شناسی، وضعیت پوشش گیاهی و عوامل اقلیمی بستگی دارد که باعث افزایش آسیب‌پذیری یک منطقه به فرسایش می‌شود. یکی از مهم‌ترین رخساره‌های فرسایشی رخساره هزاردره یا بدلند است. رخساره فرسایشی هزاردره معمولاً به مناطق با رسوبات سست و غیرمتراکم، پوشش گیاهی بسیار ضعیف یا فاقد پوشش گیاهی که به‌دلیل تراکم بالای شیارها و بریدگی‌ها برای کشاورزی غیرقابل استفاده است، اشاره می‌کند. فرسایش هزاردره بیش‌تر در مناطق خشک و نیمه‌خشک مشاهده می‌شود و در واقع برهم‌کنش بارش با مواد زمین‌شناسی سست بسیار مساعد ایجاد و گسترش رخساره هزاردره در مناطق خشک و نیمه‌خشک است. با توجه به اینکه فرسایش خاک یک فرایند بسیار پیچیده و تحت تأثیر ویژگی‌های سطح زمین، نوع خاک و دیگر عامل‌های محیط‌زیستی است، بررسی کمی و تهیه نقشه‌های حساسیت‌پذیری فرسایش امری بحث برانگیز است. هدف اصلی از پژوهش حاضر، تهیه نقشه حساسیت فرسایش هزاردره در حوزه آبخیز فیروزکوه با استاده از مدل نسبت فراوانی است. مواد و روش‌‌هاحوزه آبخیز فیروزکوه به این دلیل به‌عنوان منطقه موردمطالعه انتخاب شد که رخساره فرسایش هزاردره مهم‌ترین نقش را در فرسایش خاک این حوزه به‌دلیل وضعیت اقلیمی، هیدرولوژیکی، توپوگرافی و کاهش پوشش گیاهی و همچنین وجود سازندهای مستعد فرسایش دارد. اولین گام در این پژوهش تهیه نقشه پراکنش رخساره‌های هزاردره و تعیین محل آنها روی نقشه است. این کار با استفاده از تصاویر گوگل ارث و پیمایش زمینی انجام شد. نقشه‌های مربوط به عوامل مؤثر از منابع مختلف تهیه و وارد محیط نرم‌افزار Arc/GIS شد. با استفاده از نقاط و خطوط ارتفاعی موجود در نقشه‌های توپوگرافی تهیه شده از سازمان نقشه‌برداری کشور، نقشه مدل رقومی ارتفاع (DEM) با اندازه پیکسل 30 متر تهیه شد. نقشه‌های جهت شیب، درجه شیب، انحناء سطح، شاخص رطوبت توپوگرافی (TWI) و طبقات ارتفاع با استفاده از نقشه DEM و در محیط نرم‌افزارهای ArcGIS10.3 و SAGA-GIS به‌دست آمد. نقشه زمین‌شناسی منطقه نیز از نقشه زمین‌شناسی ایران با مقیاس 1:100000 استخراج شد. نقشه‌های آبراهه و جاده از نقشه توپوگرافی 1:25000 استخراج شده و فاصله از این عوارض در محیط Arc/GIS10.3 محاسبه شد. نقشه کاربری اراضی حوزه آبخیز فیروزکوه با استفاده از تصاویر لندست 8 برای سال 2020 و با روش تلفیقی به‌دست آمد. برای تهیه نقشه مشخصات مربوط به خاک 30 نمونه خاک از عمق صفر تا 30 سانتی‌متری برداشت و در آزمایشگاه بررسی شد. نقشه بارش متوسط سالانه با استفاده از داده‌های بارش ایستگاه‌های هواشناسی تهیه شد. بعد از طبقه‌بندی نقشه‌های مربوط به عوامل مؤثر، وزن هر نقشه با استفاده از مدل نسبت فراوانی محاسبه شد. در مرحله بعد با جمع کردن وزن‌ها، نقشه نهایی حساسیت فرسایش هزاردره تهیه شد. منحنی ROC و سطح زیر این منحنی برای ارزیابی دقت مدل نسبت فراوانی استفاده شدند. نتایج و بحثارتباط بین فرسایش هزاردره و عوامل مؤثر با استفاده از مدل نسبت فراوانی بررسی شد. نتایج نشان داد که بیش‌ترین وزن نسبت فراوانی مربوط به طبقه ارتفاعی 1710 تا 2286 متر، بارش 400 تا 550، شیب بیش‌تر از 35، جهت شمال غرب، فاصله کم‌تر از 1150 متر از آبراهه، سازندهای مارنی، آهکی و شیل، کاربری مرتع، شیب‌های محدب و مقعر، طبقه رس 25 تا 33 درصد، طبقه سیلت 27 تا 35 درصد، گروه هیدرولوژیک C، عمق خاک 57 تا 120 سانتی‌متر، اسیدیته 7.6 تا 8.1، طبقه 6 تا 11 شاخص TWI بوده است. بررسی دقت مدل نسبت فراوانی با استفاده از منحنی ROC و سطح زیر این منحنی انجام شد. سطح زیر منحنی ROC 0.71 به دست آمد که نشان می‌دهد مدل نسبت فراوانی برای تهیه نقشه حساسیت فرسایش هزاردره در حوزه آبخیز فیروزکوه قابل قبول است. مدل نسبت فراوانی با وجود سادگی، به‌دلیل ایجاد ارتباط منطقی بین هزاردره‌ها و عوامل مؤثر بر آن نتایج قابل قبولی ارائه می‌کند. مطالعات دیگری ازجمله بررسی پتانسیل آب‌های زیرزمینی، تهیه نقشه حساسیت زمین‌لغزش و آسیب‌پذیری یک منطقه به سیلاب نیز با این مدل انجام شده و دقت آن مورد تأیید قرار گرفته است. نتیجه‌‌گیریبه‌دلیل شرایط توپوگرافی، اقلیمی و زمین‌شناسی رخساره فرسایشی هزاردره یک پدیده غالب در حوزه آبخیز فیروزکوه است. در این پژوهش نقشه حساسیت فرسایش هزاردره با استفاده از مدل نسبت فراوانی تهیه شد. ارزیابی دقت نشان داد، مدل نسبت فراوانی یک مدل مناسب برای تهیه نقشه حساسیت‌پذیری فرسایش هزاردره در این حوزه آبخیز است. نتایج نشان داد که حدود 50 درصد منطقه حساسیت زیاد و خیلی زیاد به وقوع فرسایش هزاردره دارد، بنابراین توجه به این پدیده و تهیه نقشه حساسیت‌پذیری آن امری ضروری است.

Piyali Chowdhury, Indigo‐Jaie Fredericks, Jesus Castaño Alvarez et al.

Abstract This investigation explores the interactions of different shaped debris with an array of obstacles under subcritical flow conditions, representative of a flood associated with a storm surge or tsunami. Panels, blocks and cylinders were used in a flow channel, as analogues for house panels, cars/containers and trees respectively, whilst some tests used a mix of debris. The backwater effect due to the blockage caused by the obstacles was most (least) significant for panels (cylinders). There was some evidence that smaller key log types and higher flow rates led to smaller dams. It was also evident that key logs formed at different depths depending on debris shape; debris shape also determined the vertical shape of the dam. Capture efficiency had a broadly negative (positive) correlation with the Froude number (permeability). Also, from video footage there were examples of the debris moving more quickly through partial dams. Finally, the drag force, deduced from only the water depths and the flow discharge, showed a clear relationship between drag force and Froude number, and a dependency of drag force on debris shape. There are some implications for the layout of building footprints in the inundation zones and the use of large, break‐away panels.

Ziqi Yang, Lihua Xie

This letter presents a nonlinear disturbance observer-parameterized control barrier function (DOp-CBF) designed for a robust safety control system under external disturbances. This framework emphasizes that the safety bounds are relevant to the disturbances, acknowledging the critical impact of disturbances on system safety. This work incorporates a disturbance observer (DO) as an adaptive mechanism of the safety bounds design. Instead of considering the worst-case scenario, the safety bounds are dynamically adjusted using DO. The forward invariance of the proposed method regardless of the observer error is ensured, and the corresponding optimal control formulation is presented. The performance of the proposed method is demonstrated through simulations of a cruise control problem under varying road grades. The influence of road grade on the safe distance between vehicles is analyzed and managed using a DO. The results demonstrate the advantages of this approach in maintaining safety and improving system performance under disturbances.

Hendrik Alsmeier, Anton Savchenko, Rolf Findeisen

The expansion in automation of increasingly fast applications and low-power edge devices poses a particular challenge for optimization based control algorithms, like model predictive control. Our proposed machine-learning supported approach addresses this by utilizing a feed-forward neural network to reduce the computation load of the online-optimization. We propose approximating part of the problem horizon, while maintaining safety guarantees -- constraint satisfaction -- via the remaining optimization part of the controller. The approach is validated in simulation, demonstrating an improvement in computational efficiency, while maintaining guarantees and near-optimal performance. The proposed MPC scheme can be applied to a wide range of applications, including those requiring a rapid control response, such as robotics and embedded applications with limited computational resources.

Kazuhiro Sato, Ryohei Kawamura

Assessing centrality in network systems is critical for understanding node importance and guiding decision-making processes. In dynamic networks, incorporating a controllability perspective is essential for identifying key nodes. In this paper, we study two control theoretic centrality measures -- the Volumetric Controllability Score (VCS) and Average Energy Controllability Score (AECS) -- to quantify node importance in linear time-invariant network systems. We prove the uniqueness of VCS and AECS for almost all specified terminal times, thereby enhancing their applicability beyond previously recognized cases. This ensures their interpretability, comparability, and reproducibility. Our analysis reveals substantial differences between VCS and AECS in linear systems with symmetric and skew-symmetric transition matrices. We also investigate the dependence of VCS and AECS on the terminal time and prove that when this parameter is extremely small, both scores become essentially uniform. Additionally, we prove that a sequence generated by a projected gradient method for computing VCS and AECS converges linearly to both measures under several assumptions. Finally, evaluations on brain networks modeled via Laplacian dynamics using real data reveal contrasting evaluation tendencies and correlations for VCS and AECS, with AECS favoring brain regions associated with cognitive and motor functions, while VCS emphasizes sensory and emotional regions.

Aditya M. Natu, S. Hassan HosseinNia

Nanopositioning systems frequently encounter limitations in control bandwidth due to their lightly damped resonance behavior. This paper presents a novel Non-Minimum-Phase Resonant Controller (NRC) aimed at active damping control within dual closed-loop architectures, specifically applied to piezo-actuated nanopositioning systems. The control strategy is structured around formulated objectives for shaping sensitivity functions to meet predetermined system performance criteria. Leveraging non-minimum-phase characteristics, the proposed NRC accomplishes complete damping and the bifurcation of double resonant poles at the primary resonance peak through a constant-gain design accompanied by tunable phase variation. The NRC demonstrates robustness against frequency variations of the resonance arising from load changes and is also capable of damping higher-order flexural modes simultaneously. Furthermore, by establishing high gains at low frequencies within the inner closed-loop and integrating it with a conventional PI tracking controller, the NRC achieves substantial dual closed-loop bandwidths that can exceed the first resonance frequency. Moreover, the NRC significantly diminishes the effect of low-frequency reference signals on real feedback errors while effectively rejecting disturbances proximate to the resonance frequency. All contributions are thoroughly formulated and exemplified mathematically, with the controller's performance confirmed through an experimental setup utilizing an industrial nanopositioning system. The experimental results indicate dual closed-loop bandwidths of 895 Hz and 845 Hz, characterized by $\pm$3 dB and $\pm$1 dB bounds, respectively, that surpass the resonance frequency of 739 Hz.