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Seepage failure of levees can cause landslides and other hazards. Three-dimensional (3D) laser-scanning technology has become a new method for collecting levee hazard data. In this study, the 3D characteristics of landslide point clouds were investigated through systematic indoor model tests, and a feature recognition algorithm applicable to levee landslides was proposed. The major outcomes of this study are as follows: 1) the formulation of an adaptive random sampling boundary extraction (A-R-B) algorithm, which integrates random sample consensus plane segmentation, adaptive distance threshold calculation, and boundary extraction for levee landslide disaster recognition; 2) through feasibility analyses and accuracy tests of the A-R-B algorithm, this study demonstrated the capacity of the proposed method to accurately recognise the features of levee landslides, with a relative accuracy of 1 cm and an absolute accuracy of 3.5 cm in the extraction process; 3) the testing of the A-R-B algorithm and optimal parameters for the recognised levee landslide features using the point clouds obtained from laboratory models. [ABSTRACT FROM AUTHOR]

Abstract Background Oncomelania hupensis is the exclusive intermediate host of Schistosoma japonicum in China. Snail control is an essential component of schistosomiasis elimination programme. With 70 years of continuous efforts, the range of O. hupensis had reduced significantly, but slowed down in last decades. A large number of levees against flooding were constructed along Yangtze River and its affiliated lakes in the middle and lower reaches, which influenced the hydrology and ecology in the alluvial plains. The purpose of this study was to assess the impact of levees on the distribution of O. hupensis in the middle and lower reaches of the Yangtze River. Methods The snail habitats were digitalised by hand-held GPS system. The years for discovery and elimination of snail habitats were extracted from historical records. The accumulated snail-infested range for each habitat was calculated on the basis of annual reports. The current distribution of O. hupensis was determined by systematic and environmental sampling. The geographical distribution of levees was obtained from satellite imagery. To assess the impact of levees, the data pertaining to O. hupensis were divided into two parts: inside and outside the Yangtze River. Joinpoint regression was utilised to divide the study time span and further characterise the regression in each period. The 5-year-period moving averages of eliminated area infested by snails were calculated for the habitats inside and outside Yangtze River. The moving routes of corresponding geographical median centres were simulated in ArcGIS. Hotspot analysis was used to determine the areas with statistical significance clustering of O. hupensis density. Results Three periods were identified according to Joinpoint regression both inside and outside Yangtze River. The area infested by O. hupensis increased in the first two periods. It decreased rapidly outside Yangtze River year over year after 1970, while that inside the Yangtze River did not change significantly. Furthermore, the latter was significantly higher than the former. It was observed that the present density of O. hupensis inside Yangtze River was lower than outside the Yangtze River. The median centre for eliminated ranges inside Yangtze River wavered between the east (lower reach) and the west (middle reach). In contrast, the median centre for eliminated ranges continuously moved from the east to the west. Conclusions Our findings indicated that the levees had a considerable negative impact on the distribution of O. hupensis outside Yangtze River. Some hotspots observed in the irrigation areas need a sluice system at the inlet of branch for snail control. The major distribution of O. hupensis located in Hubei might be caused by severe waterlogging. The intensive surveillance should be implemented there. The biggest two freshwater lakes, the major endemic regions historically, were identified as cold spots. The long-term impact of Three Gorges Dam on the distribution of O. hupensis in the lakes should be monitored and evaluated. Graphical Abstract

The lateral connectivity of Suncheon’s Dong stream was evaluated based on landside, waterside, and levee data of the river. A total of six items was evaluated, crosssectional structure, vegetation cover ratio, connecting waterway gate, levee slopes, urbanized area ratio and wetland area ratio. Among the items, the connectivity was high in the following order: cross-sectional structure, urbanization area ratio, and levee slope. In a total of 16 survey areas of Suncheon’s Dong stream, one, 12, and three areas were evaluated as continuity, damaged, and discontinuity respectively. The downstream section was evaluated as one continuity and three damaged, the lower-middle stream section was evaluated as one damaged and three discontinuity, and the upper-middle stream and upstream sections were evaluated as eight damaged. The cross-sectional structure, vegetation cover ratio, levee slope, and urbanized area ratio had low lateral connectivity in the lower-middle stream survey section, while the wetland area ratio had high lateral connectivity in the downstream survey section. The lateral connectivity evaluation results of the river aquatic ecosystem in Suncheon’s Dong stream can be used as basic data that is helpful in future ecological river management policies.

Somalia has experienced extreme flash floods in recent years across the arid regions causing tremendous loss of lives and properties. However, the flood magnitude, depth, and frequency of occurrence are not yet quantified. This is mainly due to scarce datasets in the area. . In this study, integration of observed and Climate Hazards Infrared Precipitation (CHIRP) satellite rainfall products and remote sensing raster data were used to improve hydrological model simulation outputs. The Hydrologic Engineering Center namely HEC-HMS and HEC-RAS models were used to simulate the rainfall-runoff processes and flood inundation, respectively. The land use, soil, slope and Digital Elevation map (DEM) were used to set-up the models and generate outputs. The HEC-HMS model calibration results depict that the model is able to reproduce the observed streamflow The simulated flows generated by the model predicted good agreement with the observed flow with values of 0.79, 0.74, 0.78, and 0.78 evaluated through the Nash and Sutcliffe Efficiency (NSE), Runoff Volume Error (RVE), coefficient of determination (R2), and percentage error of peak flow (PEPF), respectively. The HEC-RAS model result indicates that the maximum flood depth and velocity were obtained at the floodplain area. The peak flood at 50, 100, and 200-year return period using General Extreme Value (GEV) distribution revealed 384m3s-1, 409m3s-1, and 434m3s-1, respectively. The 100-year peak flood discharge in a specific part of the river revealed a flood depth of 7.53m. The provision of Levees as mitigation measures revealed reduction of the flood extent by 35% and suggested as possible flood protection measures for the study area.

Background: Oncomelania hupensis is the exclusive intermediate host of Schistosoma japonicum in China. Snail control is an essential component of schistosomiasis elimination programme. With 70 years of continuous efforts, the range of O. hupensis had reduced significantly, but slowed down in last decades. A large number of levees against flooding were constructed along Yangtze River and its affiliated lakes in the middle and lower reaches, which influenced the hydrology and ecology in the alluvial plains. The purpose of this study was to assess the impact of levees on the distribution of O. hupensis in the middle and lower reaches of the Yangtze River. Methods: The snail habitats were digitalised by hand-held GPS system. The years for discovery and elimination of snail habitats were extracted from historical records. The accumulated snail-infested range for each habitat was calculated on the basis of annual reports. The current distribution of O. hupensis was determined by systematic and environmental sampling. The geographical distribution of levees was obtained from satellite imagery. To assess the impact of levees, the data pertaining to O. hupensis were divided into two parts: inside and outside the Yangtze River. Joinpoint regression was utilised to divide the study time span and further characterise the regression in each period. The 5-year-period moving averages of eliminated area infested by snails were calculated for the habitats inside and outside Yangtze River. The moving routes of corresponding geographical median centres were simulated in ArcGIS. Hotspot analysis was used to determine the areas with statistical significance clustering of O. hupensis density. Results: Three periods were identified according to Joinpoint regression both inside and outside Yangtze River. The area infested by O. hupensis increased in the first two periods. It decreased rapidly outside Yangtze River year over year after 1970, while that inside the Yangtze River did not change significantly. Furthermore, the latter was significantly higher than the former. It was observed that the present density of O. hupensis inside Yangtze River was lower than outside the Yangtze River. The median centre for eliminated ranges inside Yangtze River wavered between the east (lower reach) and the west (middle reach). In contrast, the median centre for eliminated ranges continuously moved from the east to the west. Conclusions: Our findings indicated that the levees had a considerable negative impact on the distribution of O. hupensis outside Yangtze River. Some hotspots observed in the irrigation areas need a sluice system at the inlet of branch for snail control. The major distribution of O. hupensis located in Hubei might be caused by severe waterlogging. The intensive surveillance should be implemented there. The biggest two freshwater lakes, the major endemic regions historically, were identified as cold spots. The long-term impact of Three Gorges Dam on the distribution of O. hupensis in the lakes should be monitored and evaluated. [ABSTRACT FROM AUTHOR]

Seepage is a typical hydraulic factor that can initiate the breaching process in a levee system. If not identified and treated on time, seepages can be a severe problem for levees, weakening the levee structure and eventually leading to collapse. Therefore, it is essential always to be vigilant with regular monitoring procedures to identify seepages throughout these levee systems and perform adequate repairs to limit potential threats from unforeseen levee failures. This paper introduces a fully convolutional neural network to identify and segment seepage from the image in levee systems. To the best of our knowledge, this is the first work in this domain. Applying deep learning techniques for semantic segmentation tasks in real-world scenarios has its own challenges, especially the difficulty for models to effectively learn from complex backgrounds while focusing on simpler objects of interest. This challenge is particularly evident in the task of detecting seepages in levee systems, where the fault is relatively simple compared to the complex and varied background. We addressed this problem by introducing negative images and a controlled transfer learning approach for semantic segmentation for accurate seepage segmentation in levee systems. [ABSTRACT FROM AUTHOR]

In recent years, Iran has been dealing with a significant problem. A consistent lack of rainfall, often distributed unevenly across different areas and times. Such weather issues have led to a growing demand for groundwater, resulting in serious social, economic, and engineering challenges in various regions. This study focuses on a thorough examination of the practicality of constructing a reservoir in Kariyan village, located in the Hormozgan province, capable of storing nearly one million cubic meters of runoff water. Various engineering analysis techniques were employed to understand critical parameters that determine the effectiveness of such infrastructure. These parameters include rainfall pattern, rate of evaporation, water pricing, the permeability of the reservoir, local geography, and proximity to the area where the water is needed. This research not only sheds light on the specific case of Kariyan village, but also provides a useful framework that can be applied to similar situations elsewhere. By adopting this comprehensive approach as a practical model, regions grappling with similar water resource challenges can improve their water management, reduce potential negative impacts, and move towards sustainable solutions. This study offers practical insights and strategies to improve water management in arid regions, facilitating sustainable solutions to address water scarcity challenges and minimize negative impacts on communities and ecosystems, also offering practical insights and strategies to ensure the preservation of this essential resource for future generations. [ABSTRACT FROM AUTHOR]

AbstractA quasi-real-scale experiment was conducted to understand seepage in levees with internal transverse structures. The experiment involved fabricating levees with transverse structures in the same location and using the same method as that in sand levee experiments previously conducted to examine the feasibility of the optical-fiber-distributed temperature system. Levees with internal structures are susceptible to internal erosion and piping risks, which necessitates the installation of water barriers to mitigate these issues. However, conventional concrete water barriers require curing time, leading to potential secondary damage from flooding during construction. As a countermeasure, a compounded polypropylene (PP) water barrier was developed, which is easy to construct and cost-effective. The performances of both concrete and compounded PP water barriers were verified and compared. Water pressure changes inside the levees were tracked, and to monitor temperature changes inside the levees and gain a deeper understanding of seepage, distributed optical fiber cables were employed. The experimental results revealed that levees with transverse structures had a higher risk of internal erosion and piping due to seepage compared to those without such structures, and such levees require continuous monitoring. Furthermore, internal temperature measurements demonstrated the effectiveness of water barriers in mitigating seepage and backward erosion piping.

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revue Française de Géotechnique is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heavy rain events that accompany recent climate change, have triggered disasters of embankment structures, such as road embankment and levee. Internal erosion, which is the migration of soil particles following seepage flow, causes inhomogeneity of the soil properties of the embankment. However, there are very few studies investigating the effects of soil inhomogeneities on the seepage behavior of groundwater within embankment. In this study, small-scale modelling tests were performed under repeated seepage flow histories. As a result, the groundwater table gradually increased in accordance with the number of seepage repetition. Modelling the fluctuation of permeability due to internal erosion following seepage flow was additionally performed using the soil/water/air coupled finite element analysis, and seepage behavior was investigated. In these analyses, the lower permeability of the toe of embankment was shown to possibly cause an increase in upward water pressure.

Seepage is a typical hydraulic factor that can initiate the breaching process in a levee system. If not identified and treated on time, seepages can be a severe problem for levees, weakening the levee structure and eventually leading to collapse. Therefore, it is essential always to be vigilant with regular monitoring procedures to identify seepages throughout these levee systems and perform adequate repairs to limit potential threats from unforeseen levee failures. This paper introduces a fully convolutional neural network to identify and segment seepage from the image in levee systems. To the best of our knowledge, this is the first work in this domain. Applying deep learning techniques for semantic segmentation tasks in real-world scenarios has its own challenges, especially the difficulty for models to effectively learn from complex backgrounds while focusing on simpler objects of interest. This challenge is particularly evident in the task of detecting seepages in levee systems, where the fault is relatively simple compared to the complex and varied background. We addressed this problem by introducing negative images and a controlled transfer learning approach for semantic segmentation for accurate seepage segmentation in levee systems.

Sowing is a well‐established restoration technique to overcome dispersal limitation. Seed mixtures adapted to certain environmental conditions, like substrate or microclimate, are most effective to achieve functional communities. This is especially important if the restored vegetation has to protect critical infrastructure like roadsides and dikes. Here, an improved seed–substrate combination will secure slope stability, make restorations more effective and generate species‐rich grasslands.A full‐factorial field experiment addressed this topic on a dike at River Danube in SE Germany in 2018–2021. Within 288 plots, we tested three sand admixtures, two substrate depths, two seed densities and two seed mixture types (mesic hay meadow and semidry calcareous grassland) in north and south exposition and measured the recovery completeness by calculating the successional distance to reference sites, the persistence of sown species and the Favourable Conservation Status (FCS) of target species.Overall, the sown vegetation developed in the desired direction, but a recovery debt remained after 4 years, and some plots still showed similarities to negative references from ruderal sites. In north exposition, hay meadow seed mixtures developed closer to their reference communities than dry grassland mixtures to their reference.In south exposition, the sown communities established poorly, which might be due to a severe drought during establishment. This initial negative effect remained over the entire observation period.Sand admixture had a slightly positive effect on target variables, while the tested substrate depths, seed densities and seed mixture types had no effects on species persistence or FCS.Synthesis and applications: Site‐adapted seed mixtures make restoration more effective, while applying several seed–substrate combinations might foster beta diversity. Furthermore, additional management efforts are recommended, as they might be necessary to reduce the recovery debt, as well as re‐sowing after unfavourable conditions like droughts. [ABSTRACT FROM AUTHOR]

Sediment ejecta is a mechanism that significantly contributes to the severity of liquefaction-induced ground failures. Consequently, it is essential to quantify the hydraulic demand and qualitatively estimate the sediment ejecta for assessing the ground failure severity. However, the methodology for this quantification has not been thoroughly studied. Evaluation of sediment ejecta provides an accurate estimate for adopting cost-effective and reliable measures for soil strengthening. The problem of sediment ejecta could be more severe if it occurs on the constructed ground surrounded by a residential area, as it would affect the build area and human life. Therefore, for the present study, a levee constructed over the level ground of dimensions 20 m × 10 m is analysed under plain strain conditions using the finite element method. For a better understanding of the behaviour, the effective stress analysis (ESA) is conducted on two models: soil Model 1 without a levee and soil Model 2 with a levee. In both instances, the hydraulic demand (AFP, Artesian Flow Potential), ground failure severity (EPI, Ejecta Potential Index) and the flow path of pore fluid are estimated. Observations indicate the occurrence of sediment ejecta in both the cases leading to extreme ground failure conditions. The hydraulic demand with levee is 5.49 m3 producing upto 680 m3 · s of EPI, which is significant to cause huge sediment ejecta and create extreme ground failure condition. It drags the attention towards the need to study the sediment ejecta manifestation and its effects on levee. Additionally, the flow path of pore fluid is also studied, indicating a diversion of pore-water flow towards the region of high permeability due to the levee's construction. The findings of Finite Element (FE) based effective stress analysis corroborate that the construction of a levee on the liquefiable ground causes sediment ejecta during an earthquake. Major contributing factors include soil densification, ground non-uniformity due to differential permeability between soil layers, and additional overburden from levee. Because of these combined factors, the ejected sediment creates a discontinuity within the soil model. It is evident from the flow path of pore fluid in Model 2, which highlights the ground's discontinuity, affecting the levee's dynamic stability. Therefore, methods need to be proposed to strengthen the soil and increase its stiffness, providing more stability to levee. [ABSTRACT FROM AUTHOR]

This paper presents an innovative digital twin dam and watershed management platform, K-Twin SJ, that utilizes real-time data and simulation models to support decision-making for flood response and water resource management. The platform includes a GIS-based geospatial digital twin of the entire Sumjin dam and river water system in Korea, with high-precision geospatial topography and facility information for dams and rivers (watershed area 4913 km2, river length 173 km, and 91 water infrastructures). The platform synchronizes real-time data such as rainfall, dam and river water levels, flow rate, and closed-circuit television (CCTV), and incorporates three hydraulic and hydrological simulation models for efficient dam operation considering the river conditions. AI technology is also used to predict the river water level and suggest optimal dam discharge scenarios. Additionally, the platform includes a geotechnical safety evaluation module for river levees, advanced drone monitoring for dams and rivers, and an AI CCTV video surveillance function. The digital-twin-based platform supports efficient decision-making for smart flood responses and contributes to reducing flooding damage and optimal operation through better smart water management. [ABSTRACT FROM AUTHOR]

Sand boils can contribute to the liquefaction of a portion of the levee, leading to levee failure. Accurately detecting and segmenting sand boils is crucial for effectively monitoring and maintaining levee systems. This paper presents SandBoilNet, a fully convolutional neural network with skip connections designed for accurate pixel-level classification or semantic segmentation of sand boils from images in levee systems. In this study, we explore the use of transfer learning for fast training and detecting sand boils through semantic segmentation. By utilizing a pretrained CNN model with ResNet50V2 architecture, our algorithm effectively leverages learned features for precise detection. We hypothesize that controlled feature extraction using a deeper pretrained CNN model can selectively generate the most relevant feature maps adapting to the domain, thereby improving performance. Experimental results demonstrate that SandBoilNet outperforms state-of-the-art semantic segmentation methods in accurately detecting sand boils, achieving a Balanced Accuracy (BA) of 85.52%, Macro F1-score (MaF1) of 73.12%, and an Intersection over Union (IoU) of 57.43% specifically for sand boils. This proposed approach represents a novel and effective solution for accurately detecting and segmenting sand boils from levee images toward automating the monitoring and maintenance of levee infrastructure.

This study aimed to experimentally understand the seepage mechanism in levees and evaluate the applicability of an optical-fiber distributed temperature system based on Raman-scattered light as a levee stability monitoring method. To this end, a concrete box capable of accommodating two levees was built, and experiments were conducted by supplying water evenly to both levees through a system equipped with a butterfly valve. Water-level and water-pressure changes were monitored every minute using 14 pressure sensors, while temperature changes were monitored using distributed optical-fiber cables. Levee 1, composed of thicker particles, experienced a faster water pressure change, and a corresponding temperature change was observed due to seepage. While the temperature change inside the levees was relatively smaller than external temperature changes, measurement fluctuations were significant. Additionally, the influence of external temperature and the dependence of temperature measurements on the levee position made intuitive interpretation challenging. Therefore, five smoothing techniques with different time intervals were examined and compared to determine their effectiveness in reducing outliers, elucidating temperature change trends and enabling the comparison of temperature changes at different positions. Overall, this study confirmed that the optical-fiber distributed temperature system combined with appropriate data-processing techniques can be more efficient than existing methods for understanding and monitoring levee seepage. [ABSTRACT FROM AUTHOR]

The study compared the life cycle environmental impacts of three coastal flood management strategies: grey infrastructure (levee), green–grey infrastructure (levee and oyster reef), and a do-nothing scenario, considering the flood damage of a single flooding event in the absence of protection infrastructure. A case study was adopted from a New Orleans, Louisiana residential area to facilitate the comparison. Hazus software, design guidelines, reports, existing projects, and literature were utilized as foreground data for modelling materials. A process-based life cycle assessment was used to assess environmental impacts. The life cycle environmental impacts included global warming, ozone depletion, acidification, eutrophication, smog formation, resource depletion, ecotoxicity, and various human health effects. The ecoinvent database was used for the selected life cycle unit processes. The mean results show green–grey infrastructure as the most promising strategy across most impact categories, reducing 47% of the greenhouse gas (GHG) emissions compared to the do-nothing strategy. Compared to grey infrastructure, green–grey infrastructure mitigates 13%–15% of the environmental impacts while providing equivalent flood protection. A flooding event with a 100-year recurrence interval in the study area is estimated at 34 million kg of CO _2 equivalent per kilometre of shoreline, while grey and green–grey infrastructure mitigating such flooding is estimated to be 21 and 18 million kg, respectively. This study reinforced that coastal flooding environmental impacts are primarily caused by rebuilding damaged houses, especially concrete and structural timber replacement, accounting for 90% of GHG emissions, with only 10% associated with flood debris waste treatment. The asphalt cover of the levee was identified as the primary contributor to environmental impacts in grey infrastructure, accounting for over 75% of GHG emissions during construction. We found that there is an important interplay between grey and green infrastructure and optimizing their designs can offer solutions to sustainable coastal flood protection.

Sonic drilling, auger drilling, and cable-tool drilling are the preferred methods utilized to drill through levees and embankment dams. Sonic drilling is the most recently developed of the three and has distinct advantages over the other methods. Notably, sonic drilling offers a high rate of advance through most materials while still protecting embankments from erosion and hydrofracturing. The method is not without limitations, as cost and space constraints prevent it from being the most effective choice in some circumstances. [ABSTRACT FROM AUTHOR]

The Pantanal comprehends a set of heterogeneous and biodiverse landscapes of esteemed environmental, economic and social value. The study of soils is effective to stratify and to understanding the operation of these environments. The purpose of this study was to characterize and compare soils of lake landscapes of the Pantanal: baías (freshwater lakes), salinas (alkaline lakes) and their respective levees (sandy ridges originally with forest vegetation). For this purpose, we carried out field work with sampling, in triplicate, of superficial soil layers in 12 representative areas of low and high Nhecolândia; analytical determinations of 26 soil attributes were performed, totaling 936 response variables and statistical analyses were performed in order to synthesize the data and present the results. In both landscapes, the fine sand fraction predominates in the soil granulometry. The textural class of the soils varied from very sandy, medium sandy and medium sandy for the baías; very sandy for the levees, with particle density related to the presence of quartz; and very sandy, medium sandy, medium clayey and clayey for the salinas. In the chemical attributes and organic matter, the baías stand out for higher potential acidity (H+Al), slightly high organic matter contents and availability of metal ions, especially Fe; in the levees, higher average remaining phosphorus (Prem) are more evident; while the saline lake soils are related to more alkaline pH values, high base saturation and high Sodium Saturation Indices (ISNa). Salinas landscapes presented the highest data variability and have soil attributes that refer to the action of different environmental processes. [ABSTRACT FROM AUTHOR]

The construction of Levee or river embankment is one method adopted for flood control in Palembang. The stability of the embankment is affected by water seepage inside the embankment due to several factors including rainfall as well as the repeated rise and fall of water surface in the sea due to gravity of moon and sun. Palembang is located 106 km from the east coast of Sumatra, thus the free water surface in Musi river and its tributaries is affected by the sea level. The stability of the levee is affected by the repeated change in the water level which induces changing seepage direction. This paper discusses the stability of levees constructed along Sungai Lacak, one of Musi river tributaries. In this case the stability of the existing levees was evaluated for different conditions of free water level i.e. normal, low tide and high tide. Analysis was also conducted for the case when the levee was constructed following the guidance in Standard Nasional Indonesia (SNI 1724-2015) and Guidelines of Public Work Department (2017). Improvement on the stability was obtained if the embankment was to be rebuilt according to the specification given in the standard. The presence of riprap protects the embankment from the effect of changing seepage direction due to the rise and fall of water level, thus increased the safety factor of the ideal levee during high tide from 1.270 to 2.325.

In recent years, levees have been collapsing and residents have been being robbed of their lives and properties almost every year in Japan. For soil levees, the fluctuation of the pore water pressure in the ground is a dominant parameter of their weakening. The multipoint monitoring of the pore water pressure in a levee allows us to grasp the risk of levee collapse directly. In this study, we developed a new ultrasmall-pore water pressure gauge (UPWP gauge) whose production cost and power consumption are lower and whose installation is easier than those of commercially available pore pressure gauges. We performed basic laboratory experiments for this UPWP gauge and pooling experiments for a full-scale-model levee and assessed their performance. Our results revealed that the errors of the values measured using the UPWP gauge in the laboratory test were within ±15 mm for the set water levels. Furthermore, in the verification of the full-scale test levee, the elevation process, and the maximum pore water pressures of the UPWP and the existing pore pressure gauges were in good agreement. [ABSTRACT FROM AUTHOR]

This paper presents a methodological framework to evaluate the resilience, with the primary focus on performance degradation, of levee-protected electric power networks to flooding in a changing climate. To this end, a multi-disciplinary framework is established by integrating climate science, hydrology, and electric power network analysis. The framework quantifies the effect of climate change on flood hazard levels in a levee-protected area and the subsequent changes in the resilience of the electric power network. In the first step, the changes in the exposure of levee-protected regions to flooding hazard in a warming climate are calculated. Then, the probabilities of failure of power network components due to flooding under current and projected future climate are determined. Finally, the power system resilience index is used to assess the system resiliency for pre-flooding (baseline), historic flooding, and two projected future flooding scenarios. For demonstration, the proposed framework is applied to a levee-protected area in Northern California. The IEEE 118-bus standard test system is employed to represent the power network in the study area. Results reveal that climate change can considerably decrease the system resilience of the levee-protected electric power network. The findings of this study can contribute towards more resilient power network systems under a changing climate. [ABSTRACT FROM AUTHOR]

Steel drainage pipes that can provide both drainage and reinforcement functions are expected to give better performance in levee protection against flooding compared to the protection that can provide only either one of these functions. This study investigates the effectiveness of steel drainage pipes that combine the drainage and reinforcement functions against flooding in comparison with the pipes having only either drainage or reinforcement function through the finite element analysis validated by the simulation of the centrifuge model tests. The analysis results reveal that drainage function is crucial in minimization of deformation, while the use of steel drainage pipe protection is more reliable as protection is available in form of reinforcement even when drainage function has deteriorated. Levee protected only with reinforcement and only drainage pipes experienced 112% and 2.4% larger settlements respectively in comparison to levees protected with steel drainage pipes. The performance of a levee reinforced by steel drainage pipe against flooding is more redundant and reliable compared to the traditional method of protection which provides only one of the functions. [ABSTRACT FROM AUTHOR]

Flood embankments have played an important role in flood protection systems for centuries. Tightness evaluation of water structures should result in determining whether floods may cause seepage incidents, consequently leading to their damage or even destruction. It is assumed that the time of water passage from the river to the protected area under steady-state conditions can be a good indicator of the embankment resistance to long-term water rise. The curve of water passage times shows the values obtained at different ordinates of the dammed water and can be regarded as a characteristic parameter of flood embankment tightness. Determination of the water passage time (Tp) additionally requires finding the trajectory along which this time is the shortest possible. However, there is no need to analyse the unsteady filtration, which requires the determination of an initial condition and the course of time-dependent boundary conditions. Engineers in practice, often use the time Tpp which elapses from the beginning of flooding to the occurrence of seepage in the protected area. The relationship between the passage time (Tp) and the seepage onset time (Tpp) was analysed on a model example. Practical use of the curve of passage times is showed on the example of the reconstruction of the left-bank Warta embankment in the area of Konin. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to Typhoon Hagibis (Typhoon No. 19) in October 2019, also known as the Reiwa 1 East Japan Typhoon, many parts of the Chikuma River’s levee in Nagano Prefecture were damaged. There were instances of levee collapse due to overtopping, and an electric railway bridge also collapsed when an eroded revetment broke. In the present study, these disasters were investigated.The investigation considered both the geology - geomechanics and the hydraulics of the levee collapse due to overtopping. The results suggest that the most significant factor in the collapse of the levee was structural weakness. There were cases in which the tenacity of a levee was improved by taking simple measures against seepage. It was found that the bridge abutments washed away mainly because the river levee became a water-colliding front due to changes in the water route following the erosion of a sandbar in the process of river level decline after the peak.

This study aimed to experimentally understand the seepage mechanism in levees and evaluate the applicability of an optical-fiber distributed temperature system based on Raman-scattered light as a levee stability monitoring method. To this end, a concrete box capable of accommodating two levees was built, and experiments were conducted by supplying water evenly to both levees through a system equipped with a butterfly valve. Water-level and water-pressure changes were monitored every minute using 14 pressure sensors, while temperature changes were monitored using distributed optical-fiber cables. Levee 1, composed of thicker particles, experienced a faster water pressure change, and a corresponding temperature change was observed due to seepage. While the temperature change inside the levees was relatively smaller than external temperature changes, measurement fluctuations were significant. Additionally, the influence of external temperature and the dependence of temperature measurements on the levee position made intuitive interpretation challenging. Therefore, five smoothing techniques with different time intervals were examined and compared to determine their effectiveness in reducing outliers, elucidating temperature change trends and enabling the comparison of temperature changes at different positions. Overall, this study confirmed that the optical-fiber distributed temperature system combined with appropriate data-processing techniques can be more efficient than existing methods for understanding and monitoring levee seepage.

Repeated rapid drawdown (RDD) and rapid rise in water level during extreme events lead to the progressive development of plastic strain zones within the earth embankments with subtle, rather than obvious, visible signs of distress. The traditional approach within the framework of limit equilibrium does not account for accumulated permanent deformation with repeated hydraulic loading. Work presented herein is focused on quantifying the level of deviatoric strain, in terms of key surface deformation and distress level of earth embankment slopes, with repeated hydraulic loading. A simple linear relationship between the deviatoric strain and surface deformation at the toe of the slip surface is proposed as a function of the geometry of the slope for rotational sliding. This relationship is applied using the stress-strain data obtained from conventional triaxial testing and provides a simple means to estimate the ultimate performance limit state that corresponds to the onset of embankment slope instability. Results from a parametric study show good agreement between the numerical results and proposed analytical criterion. The proposed criterion is also compared with data from field cases reported in literature by others, and reasonably good agreement with onset of failure is obtained. Results from applying the proposed model to the case studies indicate the applicability of the proposed approach as a framework for various loading conditions, slope geometries, and material properties. [ABSTRACT FROM AUTHOR]

Deep-water channels can be bound by overbank deposits, resulting from overspilling flows, which are often ornamented with sediment waves. Here, high-resolution bathymetry, backscatter, and 2D and 3D seismic data are integrated to discern the controls on flow processes on the overbank areas of the Hikurangi Channel. Qualitative seismic interpretation and quantitative analyses of sediment wave morphologies and distributions are conducted through the shallowest 600 m of stratigraphy up to the seafloor. Four outer-bend wave fields are present throughout the studied stratigraphy on the landward margin (left margin looking down-channel) only. Originally closely spaced or combined, these fields evolved to become spatially separated; two of the separate wave fields became further subdivided into distinct outer- and inner-bend fields, whose constituent waves developed distinct differences in morphology and distribution. Sediment wave character is used to interpret the direction and strength of overbank flow. Nine controls on such flow and associated deposition are identified: flow versus conduit size, overbank gradient, flow tuning, Coriolis forcing, contour current activity, flow reflection, centrifugal forcing, interaction with externally derived flows, and interaction of overspill from different locations. Their relative importance may vary across parts of overbank areas, both spatially and temporally, controlling wave field development such that: (1) outer-bend wave fields only develop on the landward margin; (2) the influence of centrifugal force on outer-bend overbanks has increased through time, accompanying a general increase in channel sinuosity; (3) inner-bend wave fields on the landward margin form by the interaction of Coriolis-enhanced inner-bend overbank flow, and outer-bank flow from up-channel bends; (4) inner-bend fields on the oceanward margin form by the interaction of axial flow through wave troughs, and a transverse, toward-channel flow component. This work has implications for interpreting overbank flow from seafloor and seismic data, and for palaeogeographic reconstructions from outcrop data. [ABSTRACT FROM AUTHOR]

This contribution reports on the field mapping of 9 exceptionally well-exposed channel-levée complexes from Taza–Guercif Basin (NE Morocco), belonging to the Late Miocene Tachrift turbidite system. Separated from each another by hemipelagic marlstones, the mapped channel-levée complexes exhibit thicknesses in the range of 5–25 m. Four main sedimentary facies associations were mapped, including channel-fill sandstones, levée thin-bedded heterolithics, chaotic mass transport deposits, and hemipelagic marlstones. In addition, two end-member styles of channel-fills spatial stacking were recognized, reflecting different modes of channel belt development and/or location along the slope profile, namely: (a) a lateral-migration pattern, resulting from lateral migration of high-sinuosity levéed channel belts, as opposed to (b) a vertically stacked pattern, interpreted to reflect the vertical aggradation of levéed channel belts with a relatively low sinuosity. The geological map accompanying this contribution provides the basis for more in-depth sedimentological investigations on the channels of the Tachrift turbidite system.

During Hurricane Katrina in 2005 and the events thereafter, failures of levees with I-walls caused extensive flooding and damage. The geological background in the New Orleans area and associated uncertainties contributed significantly to the failures. To increase the robustness of the I-walls and levee system and reduce the associated risk of failure, the uncertainties of the system must be incorporated into the design procedures, especially in a geological environment mainly composed of sand deposits. This paper presents a robust optimization procedure to identify optimal designs for the stability of an I-walls and levee system supported on sandy foundation soil in the face of flood hazards. The uncertainties associated with the I-walls and levee system, including the strength parameters of levee and foundation soils and the height of the floodwater behind the I-walls, were considered in a systematic manner. The wall embedded depth, levee crown width, and slope ratio of the levee in the landside were considered as the design parameters. For the robust optimization, the construction cost of the I-walls and levee system and the standard deviation of the failure probability were considered as the design objectives. Finally, the multi-objective optimization resulted in a set of acceptable designs that were presented in a graphical form called Pareto front, which is combined with the knee point concept to provide useful decision aids for selecting the most preferred design that meets both the economics and performance requirements. [ABSTRACT FROM AUTHOR]

This paper presents the following three topics among new findings on reservoir architecture and hydrocarbon potential of submarine channel-levee - fan systems. Firstly, this paper summarizes characteristics and origin of new intra-channel reservoir architecture "outer-bank bars (OBBs) "・ OBBs develop on tbe outer banks of meander bends of sinuous submarine channels and dip towards the inner banks, a direction of dip opposed to that of point bars or lateral-accretion packages. This paper then discusses possible reservoir quality of OBBs and possibilities of occurrence of OBBs in fluvial channels. Secondly, this paper reviews a recent study in the geometry of submarine levees. The variation in levee thickness perpendicular to the channel shows power-law decay on steeper slopes (> 0.6°) and either exponential or logarithmic decay on gentier slopes. Grain size may also control the shape of levees. A threshold in slope gradient is here interpreted as the boundary between subcritical and supercritical flows within turbidity currents flowing over levees. Based on the geometry of submarine levees, new criteria to distinguish sand-prone levees from mud-prone levees are proposed. Finally, a new facies model of hyperpycnites is presented based on the "rhythmite" beds found on the lobe and the levees of the Toyama Deep Sea Channel in the central Sea of Japan. Hydrocarbon potential of hyperpycnites are also examined by organic carbon analysis of them. On the basis of proposed criteria to identify hyperpycnites, two potential fields of hydrocarbon; the Kutei Basin offshore East Kalimantan and the N五gata-Shin*etsu Basin to Toyama Trough, where hyperpycnites may constitute hydrocarbon source rocks, are suggested. In the latter case, a new hydrocarbon source model, which can explain origin of the "Kubiki type oil", is presented in this paper [ABSTRACT FROM AUTHOR]

Floodplain inundation has been viewed as a type of binary process set by the relative elevation between river stage and levee crest. However, recent reports in the literature show that this perception may have limited applicability. In particular, through‐bank channels, conduits that cross the main river levees or banks, facilitate conditions for an "inundation continuum," or inundation for a range of sub‐bankfull flows. Moreover, through‐bank channels and their networks provide a direct hydraulic connection between the main river and the floodplain interior. We analyzed through‐bank channel structure and floodplain topography and compared them to river surface elevation to provide greater insight on floodplain inundation processes. Results show that well‐developed levees with through‐bank channels facilitate frequent through‐bank inundation. Where levees are poorly developed, floodplain inundation occurs by overbank flow. Therefore, for a given discharge through‐bank and overbank inundation may occur simultaneously. For the Congaree River floodplain, we infer that this dichotomy of inundation processes leads to temporally and spatially complex inundation flow paths for a given river stage. Further, our analyses reveal that the inundation continuum concept should be considered in the context of having vertical, longitudinal, lateral, and temporal components. Plain Language Summary: Floodplains are the flat landscapes adjacent to rivers that are frequently flooded when the water level in the main river exceeds the bank height, or at bankfull river stage. Recent studies show that this traditional view is not necessarily valid because river levees and banks are not uniformly developed. We analyzed and compared measured water levels with floodplain topography, including the main riverbanks. Results show that along‐channel variations in levee height allow water to enter the floodplain at levels below the bankfull stage, and when connected to a floodplain channel network, flooding quickly develops in the floodplain interior. Additionally, the levee structure can vary such that parts of a river reach experience overbank flooding while other parts experience through‐bank flooding. Such variability in flooding processes promotes spatially and temporally complex flow paths that together facilitate floodplain sustainability. This study sheds light on the continuum of floodplain flooding processes, and on the controls of inundation processes on flow complexity and the hydraulic connectivity of the landscape. Key Points: Floodplain inundation is a fuzzy process, and the inundation continuum includes vertical, longitudinal, lateral, and temporal dimensionsThrough‐bank and overbank inundation of the floodplain occurred, on average, 1.3 and 0.6 months per year, respectivelyA range of levee geometries promotes the simultaneous occurrence of overbank and through‐bank inundation for a single discharge [ABSTRACT FROM AUTHOR]