• Korean Journal of Remote Sensing
• /
• v.24 no.2
• /
• pp.205-211
• /
• 2008

The river management in Korea had been focused on line based 2D spatial data for the developing river management application system. In this study, the polygon based 3D spatial data such as aerial photos and satellite images were selected and used through comparing their resolution levels for the river environment management. In addition, 1m detailed DEM (Digital Elevation Model) was constructed to implement the real topography information around river so that the damage area scale could be extracted for flood disaster. Also, the social environment thematic maps such as a cadastral map or land cover map could be used to verify the real damage area scale by overlay analysis on aerial photos or satellite images. The construction of these spatial data makes possible to present the real surface information and extract quantitative analysis to support the scientific decision making for establishing the river management policy. For the further study, the lidar surveying data will be considered as the very useful data by offering the real height information of riverbed as the depth of river so that flood simulation can give more reality.

• Journal of The Geomorphological Association of Korea
• /
• v.19 no.2
• /
• pp.113-122
• /
• 2012

The geomorphic properties of potholes at Naerin River, Inje-gun are analyzed to discover the geosites of DMZ geopark in Gangwon-do. The furrow-type potholes along the river flow are mainly found in the P1 and P2 sites. The P3 site can be divided in to the zones where the furrow-type potholes densely distribute and various types of potholes are scattered, while the various types of small potholes are scattered in the P4 site. After measuring the 44 potholes, the potholes with a U-shaped cross-section, similar directivity with river flow and deposited gravels with in them show large values in length, width, depth and slope. Because the P1 and P2 sites are characteristic in the scales and forms of potholes and show beautiful scapes, it can be suggested that they are suitable for the geosite developments.

• Economic and Environmental Geology
• /
• v.54 no.5
• /
• pp.495-503
• /
• 2021

Aggregate is a major natural resource used in SOC construction, such as housing, roads, ports, etc., and is a fundamental material for national construction. Although aggregates account for only about 4% of the construction cost, aggregates occupy about 80% of the construction volume and are essential factors that determine the quantity and quality of buildings. For river, underwater, riverbed, sea, and land aggregates, it is difficult to rapidly increase the production of aggregates when there is difficulty in supply and demand due to environmental problems and limited resources during production, whereas forest aggregates are relatively easy to increase production. Forest aggregates are considered promising as alternative aggregate resources in the future when reducing other aggregates due to their abundance of natural resources, and are an effective aggregate source that can flexibly respond to aggregate demand in accordance with well-organized plans and policies. This study proposed the plan for activating the development of forest aggregates in the case of long and short transport distances, which is a factor that has a great influence on the development, and measures for the current difficulties in forest aggregate development

• Journal of Environmental Science International
• /
• v.31 no.10
• /
• pp.861-868
• /
• 2022

The Namdae stream in Gangneung-si is one of the rivers where salmon stock is mainly maintained by natural spawning rather than artificial seedlings. There are structures including weir, and fish distribution and movement characteristics can be different by these structures. In this study, we investigated the distribution and behavioral characteristics of salmon by sighting survey within 12 km immediately upstream of the river mouth between October 2021 and February 2022. As a result, salmon distributed within 9 km from rivermouth. There were more salmon in the lower reaches of Doosan weir than in the upper reaches of that. The main spawning ground for salmon was between 7-9 km from rivermouth and around the lower part of Doosan weir. Salmon behaved for spawning in the gravel-bed area and undercut slope of the mainstream, such as mating, digging the riverbed, and competition among males. Salmon moved more slowly in the gravel-bed area than sand-bed area. Doosan weir hinders the spawning migration of salmon by frequent flow changes and terraced fishway. This study provides primary information to understand the ecological changes of salmon by environmental changes in the Namdae stream.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.5
• /
• pp.161-170
• /
• 2022

The maintenance of bridges installed in rivers is carried out through facility safety inspection and repair & reinforcement procedures according to the results. Many studies have been so far conducted on the safety check of the bridge upperstructure because of the ease of access. However as it is impossible to directly investigate whether the pier foundation installed in the river has been scoured. Management of underwater foundations has remained based on theory. In this study, the scour of the bridge foundation installed in such a river was realized in 3D form by using an echo sounder and VRS. This made it possible to predict the scour pattern through comparison and analysis with the ground height of the riverbed at the time of the bridge installation. Based on these results, if the pier foundation is used as an initial data to determine whether or not local scour is present and to predict long-term scouring, bridge collapse due to foundation scour can be prevented.

• Geomechanics and Engineering
• /
• v.27 no.6
• /
• pp.561-571
• /
• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.172-172
• /
• 2020

In recent years, soil erosion has come to be regarded as an essential environmental problem in human life. Soil erosion causes various on- and off-site problems such as ecosystem destruction, decreased agricultural productivity, increased riverbed deposition, and deterioration of water quality in streams. To solve these problems caused by soil erosion, it is necessary to quantify where, when, how much soil erosion occurs. Empirical erosion models such as the Universal Soil Loss Equation (USLE) family models have been widely used to make spatially distributed soil erosion vulnerability maps. Even if the models detect vulnerable sites relatively well by utilizing big data related to climate, geography, geology, land use, etc. within study domains, they do not adequately describe the physical process of soil erosion on the ground surface caused by rainfall or overland flow. In other words, such models remain powerful tools to distinguish erosion-prone areas at the macro scale but physics-based models are necessary to better analyze soil erosion and deposition and eroded particle transport. In this study, the physics-based Surface Soil Erosion Model (SSEM) was upgraded based on field survey information to produce sediment yield at the watershed scale. The modified model (hereafter MoSE) adopted new algorithms on rainfall kinematic energy and surface flow transport capacity to simulate soil erosion more reliably. For model validation, we applied the model to the Doam dam watershed in Gangwon-do and compared the simulation results with the USLE outputs. The results showed that the revised physics-based soil erosion model provided more improved and reliable simulation results than the USLE in terms of the spatial distribution of soil erosion and deposition.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.45-45
• /
• 2020

하천 횡단구조물 하류부에서는 고유속 및 ±압력에 의해 하상재료가 유실되는 세굴현상이 발생한다. 이러한 세굴을 방지하기 위해 횡단구조물 하류부에는 석재, 콘크리트 및 콘크리트 블록 등을 설치 및 포설하여 하상보호공을 설치한다. 하상보호공을 설치하면 설치된 부분은 세굴이 방지 되지만, 하상보호공 끝단 이후에는 지반이 노출되어 있어 노출된 지반에서 고유속 흐름 및 압력변화에 의한 세굴이 발생하는 경우가 많다. 이에 본 연구에서는 하상보호공 끝단 즉, 하상이 노출된 지반에서 압력변화에 따라 하상재료가 유실되므로 압력에너지를 감쇄시키기 위한 하상보호장치를 개발하였다. 개발한 하상보호장치는 본래 다수개가 열을 지어 메트릭스 형태로 설치되도록 하여야 하지만 실험 여건상 단일체로 수리실험을 진행하였다. 하상보호장치는 상판과 하판이 조립된 형태이며 상판과 하판 사이에 이격공간이 구비되어있다. 하상보호장치 검증을 위해 상판과 하판에 쓰이는 판은 수로재질과 같은 아크릴로 제작하였으며, 하상재료의 공극률을 반영하여 다공성 판으로 제작하였다. 다공판의 전체 구멍 면적 대비 판 면적은 35 % 로 동일하다. 상판 구멍 지름 15.0 mm, 4.5 mm 2가지로 제작하였으며, 하판 구멍 지름 3.0 mm 으로 동일하다. 압력변화가 큰 곳에서 작은 곳으로 물이 이동하게 되므로 고유속 수리조건에서 상판과 하판 사이에서의 압력변화를 측정하기 위해 판 중간에 압력계를 설치하였다. 하상보호장치 설치지점 앞 0.3 m 부근에 PIV를 설치하여 유속을 측정하였다. 실험결과 상판의 구멍 직경(15.0 mm)이 클 경우 상판부 압력이 하판부로 전달되어 하판에서 측정되는 압력이 증폭 되었으며, 상판의 다공성 구멍 직경(4.5 mm)이 작을 경우 상판부에서 하판부로 전달되는 압력이 감소하여 하판에서 측정되는 압력이 감소하였다. 상판과 하판의 다공성 구멍의 직경을 적절한 사이즈로 조절하면 상판부의 압력이 하판부로 전달되는 것을 막고 압력에 의해 하상에서 흡출되는 유사를 막을 수 있는 것으로 판단되며 추후 상판과 하판의 다공성판 구멍 직경의 상대적 차이에 따른 압력 감소효율에 관한 연구가 필요하다고 판단된다.

• Korean Journal of Ichthyology
• /
• v.34 no.4
• /
• pp.270-276
• /
• 2022

In 2020 and 2022, the habitat of brown trout (Salmo trutta) was investigated in the Soyanggang River in Chuncheon, Gangwon province. As a result of the fish survey, A total of 43 individuals brown trout were identified. The total length of brown trout was widely confirmed from 60 cm or more to less than 10 cm. In January 2020, sperm release and spawn were observed in male and female confirmed at the St. 1. Brown trout were identified stably settled in the Soyanggang River and continues to live. In addition, benthic macroinvertebrates that can act as food sources of brown trout and abundantly inhabited. The riverbed structure is evenly composed of fine gravel and gravel, which constitutes the conditions necessary for habitat and spawning. However, the spawning grounds, spawned eggs and hatched fry have not yet been clearly identified, so continuous research is needed.

• Geomechanics and Engineering
• /
• v.34 no.2
• /
• pp.209-220
• /
• 2023

In this study, a series of three-dimensional numerical analyses were carried out to investigate the penetration performance of a dynamically installed Hall anchor. The advanced coupled Eulerian-Lagrangian (CEL) technique was adopted to accurately simulate the large soil deformation during the vertical penetration of a Hall anchor. In total, 52 numerical analyses were conducted to investigate the relationship between anchor penetration depth and the initial kinematic energy. Moreover, a sensitivity analysis was performed to investigate the effects of soil shear strength and soil type on the penetration mechanism of a drop anchor under self-weight. There is a monotonic increase in the penetration depth with an increasing anchor weight when the topsoil of the riverbed is not subjected to erosion. On the other hand, all the computed depths significantly increase when soil erosion is taken into consideration. This is mainly due to an enhanced initial kinematic energy from an increased dropping depth. Both depths increase exponentially with the initial kinematic energy. An enhanced shear strength can potentially increase the side resistance and end-bearing pressure around a drop anchor, thus significantly reducing the downward penetration of a hall anchor. Design charts are developed to directly estimate penetration depth and associated plastic zone due to dynamically installed anchor at arbitrary soil shear strength and anchor kinematic energy.