River Levees Research Articles

Issues in Tsunami Countermeasures from the Viewpoint of Geotechnical Engineering

The 2011 off the Pacific coast of Tohoku Earthquake, with its epicenter off the Sanriku coast, measured the moment magnitude of 9.0, had a maximum seismic intensity of 7 in the northern part of Miyagi Prefecture, and impacted an area of 450 km. Consequently, a variety of unprecedented problems were made apparent. In particular, the human and property damage wrecked by the ensuing tsunami triggered our response for earthquake and tsunami resistance. In addition to conventional issues, such as earthquake resistance of buildings, disruption of lifelines, liquefaction of residential land and soil structures, and tsunami damage in coastal areas, there were new challenges, such as prolongation of earthquake disaster waste treatment. During the 10 years since the 2011 earthquake, tsunami countermeasures have been reexamined, and based on the concept of multiple protections, both tangible and intangible countermeasures have been advanced. This article addresses technical problems related to complex disasters, and includes the example of actual damage to a river levee in the Iwate Prefecture and the case of a building overturned by tsunami in Onagawa City, Miyagi Prefecture. It also discusses liquefaction caused by earthquakes and lists the points to be considered when selecting tsunami evacuation buildings to tackle future tsunami disasters.

Erosion Resistance Performance of Surface-Reinforced Levees Using Novel Biopolymers Investigated via Real-Scale Overtopping Experiments

This study evaluates a novel biopolymer-based material reinforcement method. A real-scale experiment minimizing flood disasters and economic losses incurred by the collapse of river levees due to overtopping was conducted. At the Andong River Experiment Center, lateral overflow was reproduced to induce levee collapse using sand, reinforced novel materials, and vegetation levees represented as cases 1, 2, and 3, respectively. The flow in the upstream and downstream areas was measured, and fluctuations in the lateral overflow discharge were calculated using an acoustic Doppler current profiler. To quantitatively verify the performance of this method, the collapse delay effect based on the surface loss rate of the levee slope was analyzed using image pixel analysis and three-dimensional point cloud modeling. Comparing the collapse delay effect of the new-material levee with that of the non-reinforced levees, we found a time delay of approximately 2.7–7 times from the occurrence of overtopping via the lateral flow to the end of the test. These results indicate that we can secure time for emergency repairs and operations by reinforcing the levee surface using the material proposed in this study. These research findings are expected to provide the basis for the proper design and construction of river levees.

A new levee control system based on geotechnical and geophysical surveys including active thermal sensing: A case study from Poland

Specific features of levees, particularly their large lengths, cause significant problems in the early and precise detection of leaks as well as erosion zones in both the levee body and subsoil. These processes are the primary threats to levees safety. Fast and relatively cheap methods for the internal investigation of levees, i.e., non-invasive geophysical methods, are used only during non-flooding periods and do not have equivalent accuracy to sensors installed in the levee. Additionally, there is no optimal monitoring method for levee leak detection during a flood. Such a method, which use a fibre-optic thermal linear sensor is very effective in the case of earth dams, but it has significant limitations when to applied to existing levees.In consequence, the primary goals of our research were to improve the thermal method for levee investigation and to propose a coherent levee investigation methodology that considers the entirety of the currently used methods.We therefore developed a new type of sensor: the Multi Points Thermal Sensor (MPointS). In our solution, thermal sensors are mounted next to one another inside the levee or/and in its subsoil by hammering them from the surface. This procedure creates a quasi-continuous line of sensors along the levee. This technology's key feature is that each sensor has an integrated micro-heater that uses an active (heating) thermal method for leak detection and in situ measurements of the seepage velocity.A pilot section of the Vistula River levee in Poland was chosen to verify the MPointS solution in addition to a geophysical, geological, and geotechnical survey. Some leakage zones on this levee were previously identified during the flood in 2010. We next used a wide variety of methods to investigate the levee during a period of non-flooding. Dynamic penetration light (DPL) soundings and geological drillings were applied in addition to geophysical methods such as ground-penetrating radar (GPR), electrical resistivity tomography (ERT), electromagnetic profiling (EMP), capacitively-coupled resistivity (CCR), and high-resolution reflection seismic imaging and multichannel analysis of surface waves (MASW).Loose zones of higher porosity in the levee and its subsoil were identified using geophysical methods. These zones also included the local leakage zones detected during the 2010 flood. However, the leakage zones themselves were not clearly and unambiguously detected by these geophysical methods. The thermal monitoring system using MPointS was next installed in accordance with the locations of the loose zones indicated by the geophysical methods. During the flood in 2019, MPointS allowed us to detect precise leakage zones and monitor whether the seepage velocity exceeded the critical values that may lead to the development of internal erosion.The results showed the importance of using a comprehensive and optimised methodology for levee investigation. MPointS proved to be an effective solution for levee leakage monitoring; however, it was found to be primarily applicable to the most vulnerable levee sections. Overall, levee investigations must be performed with cheaper and faster geophysical methods and supplemented by geotechnical surveys, which are also able to choose MPointS system locations.

The Ecosystems of the Danube Delta Biosphere Reserve state-of the-art

Taking into account the morphologic-hydrographic configuration of natural ecosystems or ecosystems partly modified by man the area, its flora and fauna communities and the long-term human impact, the two main categories of Danube Delta ecosystems associated with Razim-Sinoie lake complex, coastal marine waters and the Danube flood plain between Isaccea and Tulcea, as part of Danube Delta Biosphere Reserve, have been delimited: natural ecosystems or ecosystems partly modified by man; anthropic ecosystems. To identify and characterize ecosystems, there have been analysed the data on hydrography, morphology, biodiversity, human settlements, types of land use, spatial changes through the construction of agricultural, fisheries, forestry polders, modification of the network of channels and canals with consequences on the water circulation system inside the delta. The first category, of natural and partly modified by man ecosystems comprises 23 types (water bodies: running waters-Danube and its main branches, channels and canals; standing freshwater-lakes; standing brackish and salt waters-coastal lagoons, coastal, marine zones; wetlands: water fringe vegetation-flooded reed beds, floating reed beds , riparian willow formations, frequently flooded river levees; forests, shrubs and herbaceous vegetation: temperate riverine forests-mixed oak woods, shrubs and herbaceous vegetation, steppe meadows, meadows on low marine levees; dunes, beaches).The second category, of anthropic ecosystems includes 7 types (agricultural lands, forest areas-plantation on the river banks, fish farms, settlements-villages, towns). With the establishment of the Danube Delta Biosphere Reserve in 1990, with the statutory provisions on the protection and conservation of biodiversity, the deltaic landscape, some of the previous pressures were reduced, but the pollution of the Danube waters less consolidated beaches (Sulina, Sfântu Gheorghe, Chituc) and related with touristic activities, on ecosystems as a whole. The tourism activities also must represent not only a positive and dynamic development factor but also a practical solution to keeping the environment unaltered. These aspects were mentioned in the characterization of the ecosystems presented in this article.

The reliability of muography applied in the detection of the animal burrows within River Levees validated by means of geophysical techniques

Animal burrows in a river's earthen levee leads to water piping phenomena causing structural damage and eventual collapse during floods. Currently, the state of the art comprises case studies that deal with management and maintenance, while very few documents attempt at assessing possible animal-induced failure mechanisms. For the latter, detection and characterisation of the animal burrows is crucial and Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar are the most employed geophysical techniques. Between 2017 and 2018 a team of physicists, engineering geologists, and geophysicists has for the first time probed the possibility of exploiting the Muon Transmission Radiography (MTR) to verify the internal conservation status of levees that were visibly damaged by animal activities. The technique is a non-invasive method, currently under development, based on the detection of muons, a highly penetrating component of atmospheric cosmic rays. MTR is capable of providing angular maps of the average density of the material present in front of the detector. A test site measurement campaign was carried out with a prototype instrument placed at the side of the levee. This new survey methodology was compared to a more traditional ERT measurement, performed with a pole-dipole and dipole-dipole configuration. Moreover, the actual burrows' distribution was mapped during the demolition works using Terrestrial Laser Scanner measurements to validate and constrain results. The comparison between ERT and MTR maps shows that, in spite of some limitations, the latter is a suitable and promising technique that could successfully complement a program of geological risk assessment.

Overbank Floods of Lower Yellow River Based on Two - dimensional Numerical Simulation and Analysis

When the flow of the Yellow River is large, a large range of floodplains will be formed around the main channel, and the crisis will greatly improve safety. Analysis of the changes of flood peak shape, flood peak propagation speed and flood level at large flow rate plays an important role in the protection and flood prevention of the Yellow River levee. Based on the established two-dimensional mathematical model of Luokou to the Yellow River estuary, the data of peak flow, velocity and water level are obtained by simulation calculation. By drawing the flood peak evolution process map from Luokou to Yellow River estuary, the change of flood peak type and flood peak propagation speed are analyzed to provide technical support for flood defense.

An optical fiber-based monitoring system to study the seepage flow below the landside toe of a river levee

The development of innovative monitoring systems to mitigate the risk associated to river levee failure is a recent challenge involving synergic effort of public institutions, specialized companies and academics. The present study examines a 350 m stretch of Adige river levees, located in the Province of Bolzano (Italy) close to the village of Salorno, interested in the recent past by moderate piping phenomena and subjected to subsequent interventions for seepage control (cut-off diaphragm wall). As is customary, the levee body and its foundation soil were investigated through geophysical and geotechnical surveys. The arising results provided a multi-dimensional characterization of the levee and the nearby soil water-meadows likely to be affected by preferential paths for piping. The detection of those paths entailed the joined use of piezometers and distributed optical fiber sensing (DFOS) system, the latter installed in a shallow trench on the landside. In the last days of October 2018, Northeastern Italy was hit by a tremendous storm and the Adige river was subjected to a relevant double flooding event. This exceptional circumstance, entirely recorded by the monitoring system, gives the chance to provide insight into the seepage process undermining the levee stability.

The “Problem” of New Orleans and Diminishing Sustainability of Mississippi River Management—Future Options

Climate change forcings are having significant impacts in coastal Louisiana today and increasingly affect the future of New Orleans, a deltaic city mostly below sea level, which depends on levee and pumps to protect from a host of water-related threats. Precipitation has increased in the Mississippi River basin generally, increasing runoff, so that in recent years the Mississippi River has been above flood stage for longer periods of time both earlier and later in the year, increasing the likelihood that hurricane surge, traditionally confined to summer and fall, may compound effects of prolonged high water on river levees. The Bonnet Carré Spillway, just upstream of New Orleans has been operated more often and for longer periods of time in recent years than ever before in its nearly 100-year history. Because all rain that falls within the city must be pumped out, residents have been exposed to interior flooding more frequently as high-intensity precipitation events can occur in any season. A sustainable path for New Orleans should involve elevating people and sensitive infrastructure above flood levels, raising some land levels, and creating water storage areas within the city. Management of the lower Mississippi River in the future must include consideration that the river will exceed its design capacity on a regular basis. The river must also be used to restore coastal wetlands through the use of diversions, which will also relieve pressure on levees.

Development of Fragility Curves for Piping and Slope Stability of River Levees

The design code Eurocode 7 relies on semi-probabilistic calculation procedures, through utilization of the soil parameters obtained by in situ and laboratory tests, or by the means of transformation models. To reach a prescribed safety margin, the inherent soil parameter variability is accounted for through the application of partial factors to either soil parameters directly or to the resistance. However, considering several sources of geotechnical uncertainty, including the inherent soil variability, measurement error and transformation uncertainty, full probabilistic analyses should be implemented to directly consider the site-specific variability. This paper presents the procedure of developing fragility curves for levee slope stability and piping as failure mechanisms that lead to larger breaches, where a direct influence of the flood event intensity on the probability of failure is calculated. A range of fragility curve sets is presented, considering the variability of levee material properties and varying durations of the flood event, thus providing crucial insight into the vulnerability of the levee exposed to rising water levels. The procedure is applied to the River Drava levee, a site which has shown a continuous trend of increased water levels in recent years.

INFLUENCE OF SEEPAGE FLOW HISTORIES ON DETERIORATION WITHIN EMBENKMENTS

: Embankment structures are important to protect against flooding damage. Suffusion, in which fine particles within the soil are transported and washed away following the seepage flow, intensifies the instability of embankment structures. Therefore, it is possible that some embankment structures that repeatedly experienced flooding and rainfall penetration have been deteriorated. However, there is little research investigating the relation between seepage flow histories and deterioration within the embankments. In this study, small-scale modeling tests duplicating a river levee were conducted under different seepage flow histories: (i) short term-critical ground water level, (ii) continuous-high ground water level and (iii) repeatedhigh ground water level. The work in this paper investigates changes in “drainage flow rate”, “height of ground water level” and “particle size distribution” during the seepage tests, and evaluates the effects of seepage flow histories on them. Soils gradually showed lower permeability under the first seepage experience in each cases. In the case of relatively longer flooding duration, the drainage flow rate is gradually increased. Fine particles were eroded, regardless of the seepage flow histories; “the number of fluctuations” and “height” of ground water level could particularly be a trigger of suffusion.

Laboratory Studies Using Electrical Resistivity Tomography and Fiber Optic Techniques to Detect Seepage Zones in River Embankments

We present the results of laboratory experiments on a down-scaled river levee constructed with clayey material collected from a river embankment where a permanent resistivity instrument has operated since 2015. To create potential seepages through the levee, two zones (5 × 4 cm and 10 × 2 cm) were filled with sand during the levee construction. Electrical resistivity tomography (ERT) technique and Fiber Bragg Grating (FBG) technology were used to study time-lapse variations due to seepage. The ERT profile was spread on the levee crest and the Wenner array with unit electrode spacing a = 3 cm was used. Six organic modified ceramics (ORMOCER) coated 250 μm-diameter fibers were deployed in different parts of the levee. Time-lapse measurements were performed for both techniques from the beginning of each experiment when water was added to the river side until the water was continuously exiting from the seepage zones. The results showed that ERT images could detect seepages from the early stages. Although with a short delay compared to ERT, fiber optic sensors also showed their ability to detect water infiltrations by measuring temperature changes. Both technologies being successful, a discussion about respective peculiarities and pros and cons is proposed to suggest some criteria in choosing the proper technique according to the specific needs.

Impact of monotonic and cyclic suction variations on the thermal properties of a stabilized compacted silty soil

The soil stabilisation is employed to construct geostructures as embankments, river levees, road subbases or to backfill excavations, improving the mechanical behaviour and reducing the consumption of extracted primary aggregates. This study is focused on the use of lime/cement treated soils to backfill trenches where high power line cables are buried. Indeed, under these circumstances not only the mechanical properties but also the thermal characteristics of the treated soil are of primary importance.The effect of changes in suction (soil water content) on the thermo-mechanical properties was investigated on lime-treated and lime-hydraulic binder treated silty soils in the laboratory. The relationship between the Soil Water Retention Curve (SWRC) determined by suction control and measurement techniques, and the thermal properties along the drying path from the Optimum Proctor point (initial state) was analysed. Moreover, to investigate the successive heating/cooling periods induced by the cable, several drying/wetting cycles were applied to analyse their effect on the thermal properties and mechanical behaviour of compacted treated soils. The obtained data showed that increasing the suction from initial state to 3.5 MPa induces a decrease in the thermal conductivity (λ), this diminution becomes more important below 3.5 MPa of suction. An inverse trend was however observed in the change of the thermal capacity (C) with increasing section. The drying/wetting cycles appeared to have a significant impact on the mechanical performances and smaller effect on the thermal properties of the studied compacted treated silty soil.

Urban Black-Odor Water Remote Sensing Mapping Based on Shadow Removal: A Case Study in Nanjing

Urban black-odor water is a serious water environmental problem worldwide that seriously affects the living environment and the health of residents. The detection of black-odor water is a primary problem of centralized governance. Remote sensing is an effective means for water-quality monitoring. However, in most urban areas, with their complex underlying conditions, black-odor water always shows an uncertain distribution and small area. Furthermore, because of similar spectral characteristics, it is easily confused with dark objects such as asphalt roads, dark roofs, bridges, river levees, and building shadows. In this article, we propose a new black-odor water detection method, without shadow misjudgment, for complex urban conditions. A remote sensing image from the Chinese high-resolution satellite Gaofen-2 (GF-2) was used for detection. Using in situ water-quality measurement data for verification, the results showed that the proposed method achieved an accuracy of 85.7% while reducing the false alarm rate to 3.5%. Compared to four other existing methods, the proposed method proved to be more practical because it can reduce the false extraction of nonblack-odor water to the greatest extent possible while ensuring accuracy The method proposed in this article has a good effect on the extraction of black-odor water in Nanjing City. Therefore, our method can be applied widely to screening and management of large-scale urban black-odor water and can provide reliable data for centralized treatment.

Modelling of Flood Inundation due to Levee Breaches: Sensitivity of Flood Inundation against Breach Process Parameters

This paper analyses the sensitivity of flood inundation due to river levee breach against breach process parameters using the 1996 Awash River levee breach case at Wonji, Ethiopia. A parametric levee breach model integrated into the 2D hydrodynamic numerical model Telemac-2D is used to simulate a levee breach flood event at Wonji, Ethiopia. Levee breach process parameters are systemically varied to find out their effect on the flood inundation. The analysis of the model results shows that the flood inundation is sensitive to the final breach dimensions and breach location. However, the parameters describing the levee breach development have negligible influence on the flood inundation. This implies that final breach dimension and breach location in an event of levee breach are the most important and decisive parameters affecting the resulting inundation of the flood plain, and as such should be given due consideration when creating flood inundation maps due to levee breach.

A fully coupled particle method for dynamic analysis of saturated soil

Among other numerical issues, it is well known that the finite element method (FEM) lacks objectivity in reproducing high deformation rates due to extreme external actions. In geotechnical applications, the coupling of large solid deformations with the pore fluid flow is a critical subject, being one of the multiple scenarios where FEM could have restricted applications. In order to overcome the aforementioned numerical drawbacks, the generic theoretical approach presented in this work is implemented in the context of an explicit numerical method known as the material point method (MPM). Since the MPM can be viewed as a special Lagrangian FEM with particle quadrature and continuous mesh updating, the improved formulation and numerical implementation presented here are well suited for the study of coupled water pore pressure and soil deformation models. One important aspect of the presented coupled formulation is the assumption of two independent sets of Lagrangian material points for each phase. This characteristic leads to a numerical tool oriented to large deformations simulations in saturated porous media, with a fully coupled thermodynamically consistent formulation. To illustrate its robustness and accuracy, the approach is applied to two different real engineering applications: progressive failure modeling of a granular slope and river levees. The obtained results show that the physics of fluid flow through porous media is adequately represented in each analyzed case. It is also proved that it accurately represents the kinematics of soil skeleton and water phase for fully saturated cases, ensuring mass conservation of all constituents.

Use of weight sounding for examining the liquefaction-induced river levee failures

The liquefaction-induced river levee failures observed at micro-scale landforms of an old river course during the 2011 Tohoku earthquake were investigated by means of weight sounding and soil sampl...

THE MEASUREMENT ACCURACY AND MEASUREMENT CHARACTERISTICS OF GREEN LiDAR DRONE

Abstract. The aim of this study is to confirm the measurement accuracy and measurement characteristics of Green LiDAR Drone.In Japan, due to recent climate change, the frequency of heavy rainfall has been increasing, and more floods than estimated are occurring every year. Infrastructures that can safely drain the flood are river channel and river levee. Their role is becoming increasingly important. To reduce river disasters and manage disaster risk areas, river management administrations of Japan must understand the state of river channel and river levees. In order to fully identify risk area of disaster, it is considered using Green LiDAR Drone in Japanese river management. From these backgrounds, it is necessary to clarify the measurement accuracy and measurement characteristics of Green LiDAR Drone. Therefore, in this study, we confirmed the theoretical basic performance assumed from the device performance. Also, we conducted experimental measurements on flat ground area, river area, and coast area. Through verification of experimental measurements, we confirmed the positional accuracy, bathymetric capabilities of water area, and measurement characteristics of point cloud obtained by Green LiDAR Drone. As the result, it was confirmed the point cloud acquired by Green LiDAR Drone could understand not only the riverbed or coasts topography but also the structures of rivers and coasts, and could be used as basic information for maintenance and construction.

Monitoring of internal erosion processes by time-lapse electrical resistivity tomography

Internal erosion phenomena are a major threat to all earthen structures, such as river levees and dams. Studying these phenomena has been limited because they occur concealed inside the material, which makes them difficult to observe and monitor. Non-destructive geophysical monitoring techniques are powerful tools that can provide insight into the processes involved. For this reason, a test rig has been specifically designed to conduct three-dimensional electrical resistivity tomography of soil specimens undergoing internal erosion due to seepage. Two suffusion tests were conducted where the erosion evolution has been monitored. The time-series of eroded mass weight were then used to correlate the changes in three-dimensional resistivity distribution to the porosity change in media by means of Archie’s law. The results from the first suffusion test were used to calibrate Archie’s model parameters. It was found that the resistivity variations were able to predict changes in the porous matrix structure. The data obtained from the second test were used to validate the model parameters and confirmed that the time-lapse three-dimensional inverted resistivity images were able to successfully quantify the global erosion rate.

Seismic damage analysis on the river levees reinforced with steel sheet pile by the 2016 Kumamoto earthquake

Seismic damage analysis on the river levees reinforced with steel sheet pile by the 2016 Kumamoto earthquake

River Levee Overtopping: A Bivariate Methodology for Hydrological Characterization of Overtopping Failure

AbstractThis research presents a bivariate methodology for the hydrological characterization of the overtopping failure for an existing river levee. Conventional procedures usually consider only on...