• Korean Journal of Remote Sensing
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• v.37 no.5_3
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• pp.1425-1434
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• 2021

Continuous and periodic data acquisition must be preceded to maintain and manage the river facilities effectively. Adapting the existing general facilities methods, which include river surveying methods such as terrestrial laser scanners, total stations, and Global Navigation Satellite System (GNSS), has limitation in terms of its costs, manpower, and times to acquire spatial information since the river facilities are distributed across the wide and long area. On the other hand, the Mobile Mapping System (MMS) has comparative advantage in acquiring the data of river facilities since it constructs three-dimensional spatial information while moving. By using the MMS, 184,646,009 points could be attained for Anyang stream with a length of 4 kilometers only in 20 minutes. Levee points were divided at intervals of 10 meters so that about 378 levee cross sections were generated. In addition, the waterside maximum and average slope could be automatically calculated by separating slope plane form levee point cloud, and the accuracy of RMSE was confirmed by comparing with manually calculated slope. The reference slope was calculated manually by plotting point cloud of levee slope plane and selecting two points that use location information when calculating the slope. Also, as a result of comparing the water side slope with slope standard in basic river plan for Anyang stream, it is confirmed that inspecting the river facilities with the MMS point cloud is highly recommended than the existing river survey.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.258-266
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• 2019

This study was conducted to apply natural river technologies to levees and examine the results. The new eco-friendly bio-polymer was applied, a combination of eco-friendly biopolymers and soil, to levee slope to enhance durability and eco-friendliness and to establish reinforcement measures against unstable levees due to overtopping. A semi-prototype levee of 1 m in height, 3 m in width, with a 1:2 slope and 5 m length, was constructed at the Andong River Experiment Center. The bio-soil mixed with the biopolymer and the soil at an appropriate ratio was treated with a 5 cm thickness on the surface of levee to perform the stability evaluation according to overtopping. Using the pixel-based analysis technique using the image analysis program, the breached area of levee slope was calculated over time. As a result, the time for complete decay occurs more than 12 times than that of ordinary soil levee. Therefore, when the new substance is applied to the surface of levee, the decay delay effect appears to be high.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.185-185
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• 2011

Mapping of artificial levee lines, one of major tasks in river zone mapping, is critical to prevention of river flood, protection of environments and eco systems in river zones. Thus, mapping of artificial levee lines is essential for management and development of river zones. Coastal mapping including river zone mapping has been historically carried out using surveying technologies. Photogrammetry, one of the surveying technologies, is recently used technology for national river zone mapping in Korea. Airborne laser scanning has been used in most advanced countries for coastal mapping due to its ability to penetrate shallow water and its high vertical accuracy. Due to these advantages, use of LiDAR data in coastal mapping is efficient for monitoring and predicting significant topographic change in river zones. This paper introduces a method for construction of a 3D artificial levee line using a set of LiDAR points that uses normal vectors. Multiple steps are involved in this method. First, a 2.5-dimensional Delaunay triangle mesh is generated based on three nearest-neighbor points in the LiDAR data. Second, a median filtering is applied to minimize noise. Third, edge selection algorithms are applied to extract break edges from a Delaunay triangle mesh using two normal vectors. In this research, two methods for edge selection algorithms using hypothesis testing are used to extract break edges. Fourth, intersection edges which are extracted using both methods at the same range are selected as the intersection edge group. Fifth, among intersection edge group, some linear feature edges which are not suitable to compose a levee line are removed as much as possible considering vertical distance, slope and connectivity of an edge. Sixth, with all line segments which are suitable to constitute a levee line, one river levee line segment is connected to another river levee line segment with the end points of both river levee line segments located nearest horizontally and vertically to each other. After linkage of all the river levee line segments, the initial river levee line is generated. Since the initial river levee line consists of the LiDAR points, the pattern of the initial river levee line is being zigzag along the river levee. Thus, for the last step, a algorithm for smoothing the initial river levee line is applied to fit the initial river levee line into the reference line, and the final 3D river levee line is constructed. After the algorithm is completed, the proposed algorithm is applied to construct the 3D river levee line in Zng-San levee nearby Ham-Ahn Bo in Nak-Dong river. Statistical results show that the constructed river levee line generated using a proposed method has high accuracy in comparison to the ground truth. This paper shows that use of LiDAR data for construction of the 3D river levee line for river zone mapping is useful and efficient; and, as a result, it can be replaced with ground surveying method for construction of the 3D river levee line.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.119-123
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• 2010

Causes of the levee collapse are directly or indirectly associated with geotechnical engineering as well as hydraulics. In this paper, literature survey and analysis were conducted to present the alternatives in geotechnical engineering issues for rational levee design. The alternatives include the reasonable river-bed soil utilization and precautions of numerical analysis and slope stability analysis, disruption type and improvement method of drainage facility.

• Journal of Korea Water Resources Association
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• v.34 no.2
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• pp.141-154
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• 2001

An experimental study was performed to investigate the effects of levee crest width and the slope steepness on levee break due to overtopping flow. The phenomenon of bank failure can be described in 4 stages. In this study, the magnitudes of breach width, breach depth peak discharge, and scouring shape at the break site were measured, and the result shows that peak discharge will be reduced and breach duration extended by widening the crown width and lessening the levee slope steepness. The breach width was narrower and the breach depth deeper, as the levee crest width become wider or the slope steeper. And, the bed scour depth was deeper and steeper, as the levee crest crest width become narrower or the slope milder.

• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.81-92
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• 2014

The integrity evaluation of river levee includes slope stability evaluation of riverside land and protected low-land, and safety of piping with respect to critical gradient and critical velocity based on related regulations, such as Design Criteria Rivers Commentary (2009), Structural Design Criteria Based Commentary (2009). The design hydro-graph is the most important design input factor for the integrity evaluation; it can be inaccurate due to the absence of its decision methods suggested by the national level. The authors in this paper evaluated numerical analytic levee integrity for piping and slope stability by changing each design hydro-graph, including rising ordinary water level, lasting flood water level, falling water level, and flood frequency for Mun-san-jae on Nak-dong River. Finally, the authors suggested that the levee integrity of piping and slope stability are very sensitive to the changes of increasing time of ordinary water level by 57 hours and lasting time of the flood water level by 53 hours, respectively, for Mun-san-jae.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.104-115
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• 2014

A levee is defined as an man-made structure protecting the areas from temporary flooding. This paper suggests a methodology for establishing the levee GIS database using the airborne topographic LiDAR(Light Detection and Ranging) data taken in the Nakdong river basins and the WAMIS(WAter Management Information System) information. First, the National Levee Database(NLD) established by the USACE(United States Army Corps Engineers) and the levee information tables established by the WAMIS are compared and analyzed. For extracting the levee information from the LiDAR data, the DSM(Digital Surface Model) is generated from the LiDAR point clouds by using the interpolation method. Then, the slope map is generated by calculating the maximum rates of elevation difference between each pixel of the DSM and its neighboring pixels. The slope classification method is employed to extract the levee component polygons such as the levee crown polygons and the levee slope polygons from the slope map. Then, the levee information database is established by integrating the attributes extracted from the identified levee crown and slope polygons with the information provided by the WAMIS. Finally, this paper discusses the advantages and limitations of the levee GIS database established by only using the LiDAR data and suggests a future work for improving the quality of the database.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.712-721
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• 2017

Recently, the intensity and frequency of floods has increasing worldwide, and flood disasters have become a big problem. Flood disasters, which account for the largest portion of disasters, are floods accompanied by typhoons and localized heavy rainfall. As a result, they cause damage of levee overtopping, in which the water level of a river rises to the levee crown. Therefore, countermeasures are essential and necessary because of the damage to the facility itself as well as to life and other property. The damage magnitude depends on the collapse of the levee. A levee that is difficult to collapse will reduce the discharge inland significantly. Accordingly, the protection of the inland slope, where the collapse of the levee is initiated, is one of the most important countermeasures In this study, revetments with various porosity and forms were suggested and hydraulic experiments were carried out for each type. The hydraulic experiments showed that the stability of a revetment in an inland slope is strongly correlated with the weight per unit area of the revetment. The relationship between the critical velocity, which is the velocity at the moment of leaving the revetment, and the weight per unit area was derived. Through this study, by applying the nature friendly revetment, which has not yet been applied to Korea, it is expected that life and property damage caused by levee overtopping during flooding can be reduced, and a nature friendly river space can be constructed.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.524-528
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• 2009

An influence factors for soundness evaluation of river levee include resistibility and embankment for piping of ground consisting embankment in case piping, permeability coefficient of ground, height of embankment, the width of crest, material characteristics of embankment and foundation ground, shape of embankment slope, an influence for penetration of rainfall or river water in case slope stability. In this study, it was operated a feasibility investigation of existing design result, stability evaluation for permeability coefficient use and permeability coefficient change of foundation ground to investigate an influence in line with permeability coefficient change for result of river levee penetration analysis. The evaluation results of influence factors, the permeability coefficient used in design and it was evaluated influence in safety factor of piping. After the evaluation of influence factors, the permeability coefficient used in the design appears with the fact that differs in a design report about same soil, Accordingly, the stability investigation of embankment by application of literature data can affect stability evaluation results by change factors like a permeability coefficient, void ratio. It should be certainly used material properties by a test in soundness evaluation of river levee.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.1-8
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• 2018

Levee breaches can result from flooding due to torrential rainfalls, which are linked with recent abnormal climates and the aging of river levees. Breaches have caused enormous property damage and human casualties in lowland areas. Overtopping was found to be the cause for approximately 40% of all cases of breach. In this study, the reasons and mechanisms behind levee breaches were analyzed using hydraulic model testing. The overtopping stability and time delay effect of breaches were assessed for levees made with a new environmentally friendly substance. Image analysis revealed that the total breach time of the levees made with the new substance was about 2.25 times greater than that of an earthen levee. The initial breach rate of a general earthen levee was about 1.43 times higher than that of levees covered with the new substance, and the body collapsed rapidly. The breach mechanisms of levees covered with the new substance were completely different, and it is possible to prevent rapid breaches by mitigation of the breach speed on the slope by resisting overtopping.