• 대한토목학회논문집
• /
• 제2권2호
• /
• pp.19-28
• /
• 1982

하구(河口), 항만(港灣) 등에서 응집성(凝集性) 및 비응집성토사(非凝集性土砂)의 이송추정(移送推定)을 위한 이차원토사이송추정모형(二次元土砂移送推定模型)이 개발되었으며 이 모형(模型)은 흐름에 의한 순환모형(循環模型)과 토사이송모형(土砂移送模型)으로 구성된다. 토사이송모형(土砂移送模型)은 이차원확산(二次元擴散) 방정식(方程式)과 연속방정식(連續方程式)으로 이루어진다. 해(解)는 Galerkin 유한요소법(有限尿素法)과 이단계(二段階) Lax-Wendroff 방법(方法)에 의하였다. 이차원수로(二次元水路)의 상이(相異)한 조건하에서 순환(循環)과 토사이송(土砂移送)에 관하여 수치모의(數値模擬) 되었으며 부산항(釜山港)에 적용하여 얻어진 결과중에서 실측치(實測値)와 비교가 가능한 흐름양상(樣相)은 대체로 실측치(實測値)와 근사(近似)하게 나타났다.

• Environmental Engineering Research
• /
• 제13권2호
• /
• pp.69-72
• /
• 2008

The movement of sediments in the stream crossing a large industrial complex to the mouth of Masan Bay was monitored for eight years. Sediment samples were seasonally collected in the period of $1992{\sim}1997$ and $2001{\sim}2002$. The heavy metal content of sediment was found to be higher at dry season with the peak on February and significantly decreased at rainy season. Metals content in stream sediments were rapidly decreased by large precipitation events in rainy season because the contaminants in the upstream sediments were transported to the dredged area of Masan Bay where is a typical enclosed bay in Korea. The increasing and decreasing tendency of heavy metals in sediment was repeatedly observed for six consecutive years. The heavy metals assessment of stream sediment provide us the information about the pollutant source, transport pattern and control strategy along the industrial complex. It was strongly suggested that the transportable stream sediments of an industrial area should be controlled as one of the important strategies to restore and manage the enclosed bay. Combined wastewaters have been collected and treated in a publicly owned treatment works (POTW) after industrial wastewater treatment at each location of industries since 1994. A field study was conducted to investigate the pollutant removal efficiency and performance of contact oxidation system installed and operated in two locations in the stream. The stream sediment quality was improved since then, and as a consequence the habitat of the estuary has been restored.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2000년도 학술발표회 발표논문집
• /
• pp.365-370
• /
• 2000

Sea dike construction for the tidal flat reclamation works in estuary and coast may change the characteristics of tidal motion and wave conditions in the region. In turn, a new hydraulic condition provides the impacts on sediment transport pattern and forms a new morphological environment. Also, morphological changes during the closure works of sea dike are closely related with a safy of sea dike. Therefore, the prediction of morphological changes is required secure the safe closure work and the economic design of sea dikes. To investigate morphological changes due to sea dike construction, hydrodynamic changes of tides and waves have to be evaluated, then sediment transport and sea bottom changes are computed. Mathematical modelling is required for representation of interrelation of tidal motion, wave and sediment transport. In this study, numerical model MORSYS is applied to compute the hydrodynamics and morphological changes around the closure gap for Saemankuem dike. This model allows a flexible integration of the module for waves, currents, sediment transport and bottom changes.

• Journal of the korean society of oceanography
• /
• 제35권1호
• /
• pp.1-10
• /
• 2000

A two-dimensional numerical model was applied to investigate the sediment transport and sand bank formation in a macrotidal sea, the Kyunggi and Asan Bays. The tidal residual currents show quite complex pattern including counter-rotating eddies off the northwestern corner of the Dugjeok Island that reflect the promontory effect. Complex residual eddies are also present off the coast of the Taeanbando and in the Asan Bay. Net sediment transport pattern shows that sandy sediments in the Kyunggi and Asan Bays are generally transported landward from the outer sea suggesting sediment trapping inside the bays. This phenomenon may be related to the formation and maintenance of numerous sand banks in this macrotidal sea. Alternate occurrences of deposition and erosion predicted from the numerical model along the coast of the Taeanbando with strong deposition on the southwestern part of the 'Jangansatoe'(JSB), a large sand ridge off the coast of the Taeanbando appear to reflect the loose connection of JSB, The 'Joongangcheontoe', a central sand bank (CSB) with the main axis in the NW-SE direction in the Asan Bay may undergo a modification with strong deposition along the northeastern flank. These results indicate that the sand banks are actively modified and maintained by the strong tidal currents in this shallow macrotidal sea.

• Ocean Systems Engineering
• /
• 제6권1호
• /
• pp.61-97
• /
• 2016

This is the second of two papers on the 3D numerical modeling of nearshore hydro- and morphodynamics. In Part I, the focus was on surf and swash zone hydrodynamics in the cross-shore and longshore directions. Here, we consider nearshore processes with an emphasis on the effects of oceanic forcing and beach characteristics on sediment transport in the cross- and longshore directions, as well as on foreshore bathymetry changes. The Delft3D and XBeach models were used with four turbulence closures (viz., ${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES) to solve the 3D Navier-Stokes equations for incompressible flow as well as the beach morphology. The sediment transport module simulates both bed load and suspended load transport of non-cohesive sediments. Twenty sets of numerical experiments combining nine control parameters under a range of bed characteristics and incident wave and tidal conditions were simulated. For each case, the general morphological response in shore-normal and shore-parallel directions was presented. Numerical results showed that the ${\kappa}-{\varepsilon}$ and H-LES closure models yield similar results that are in better agreement with existing morphodynamic observations than the results of the other turbulence models. The simulations showed that wave forcing drives a sediment circulation pattern that results in bar and berm formation. However, together with wave forcing, tides modulate the predicted nearshore sediment dynamics. The combination of tides and wave action has a notable effect on longshore suspended sediment transport fluxes, relative to wave action alone. The model's ability to predict sediment transport under propagation of obliquely incident wave conditions underscores its potential for understanding the evolution of beach morphology at field scale. For example, the results of the model confirmed that the wave characteristics have a considerable effect on the cumulative erosion/deposition, cross-shore distribution of longshore sediment transport and transport rate across and along the beach face. In addition, for the same type of oceanic forcing, the beach morphology exhibits different erosive characteristics depending on grain size (e.g., foreshore profile evolution is erosive or accretive on fine or coarse sand beaches, respectively). Decreasing wave height increases the proportion of onshore to offshore fluxes, almost reaching a neutral net balance. The sediment movement increases with wave height, which is the dominant factor controlling the beach face shape.

• 한국환경과학회지
• /
• 제19권10호
• /
• pp.1219-1227
• /
• 2010

In this study, the sensitivity analysis of bed changes due to the various sediment transport equations have been conducted for 80 km reach of the Lower Nakdong River using the HEC-6 which is one dimensional numerical model. The bed elevation changes according to the different sediment transport formulas were compared and analyzed quantitatively. As a result of the numerical simulation, the final bed elevation calculated by Engelund and Hansen(1967), Ackers and White(1973), and Yang(1979) formulas was similar to one another in configuration. The bed change simulated by Engelund and Hansen(1967) were greatest among them, for example, 5.5 m deposition and 2.9 m erosion for 100 years. Also, in the case of Toffaleti (1969) equation, the maximum bed deposition of 8.04 m after 100 years was induced at the 73 km location upstream of the Nakdong River Estuary Barrage. Meyer-Peter-M$\ddot{u}$ller(1948) and Wilcock(2001) formulas produced the deposition only at the upstream end and there was little bed change in the downstream area. The unreal bed configuration of continuously up and down pattern was simulated by Laursen(1958) transport equation.

• 한국해양환경ㆍ에너지학회지
• /
• 제6권4호
• /
• pp.67-82
• /
• 2003

해양, 하천, 호수 등에서 퇴적물 수송과정을 모의할 수 있는 2차원 모형을 수립하였으며, 홍수시 대청호로 유입되는 입자성 오염물질의 이동경로를 파악하기 위하여 부유퇴적물 이동-확산 모델링을 시도하였다. 또한, 복잡한 지형을 가진 대청호의 흐름특성을 파악하고, 퇴적물 수송모형의 입력자조로 이용하기 위하여 2차원 흐름모델링을 수행하였다 홍수시 모의된 수위변화는 관측결과와 일치하는 양호한 계산결과를 보였다. 평상시는 유속이 5 cm/sec이하였으나, 최대유량이 3,852 CMS에 달하는 홍수시 대청호 유입수로에서 최강유속은 최대 약120 cm/sec까지 증가하였다 대청호로 유입되는 세립질 부유사는 홍수시는 대청댐까지 강한 유속에 의해 도달하나 유속이 약한 평상시에는 대청댐까지 도달하지 못하고 대부분 유입수로에 침전하였다 모의결과는 대청호 수질관리대책을 수립하는데 기초자료로 활용될 수 있을 것이다.

• Journal of the korean society of oceanography
• /
• 제39권1호
• /
• pp.57-71
• /
• 2004

Based on the data obtained under the China-Korea joint project (1997-2001) and historic observations, the distribution, transportation and sedimentation of sediment in the southern Yellow Sea (SYS) are discussed, and the controversial formation mechanism of muddy sediments is also explored. The sediment transport trend analysis indicates that the net transport direction of sediment in the central SYS (a fine-grained sediment deposited area) points to $123.4^{\circ}E,\;35.1^{\circ}N$, which is a possible sedimentation center in the central SYS. The sediment transport pattern is verified by the distribution of total suspended matter (TSM) concentration and ${\delta}^{13}C$ values of particulate organic carbon (POC), the latter indicates that the bottom water plays a more important role than the surface water in transporting the terrigenous material to the central deep-water area of the SYS, and the Yellow Sea circulation is an important control factor for the sediment transport pattern in the SYS. The carbon isotope signals of organic matter in sediments indicate that the Shandong subaqueous delta has high sedimentation rate and the deposited sediments originate mainly from the modern Yellow River. The terrigenous sediments in deep-water area of the SYS originate mainly from the old Yellow River and the modern Yellow River, and only a small portion originates from the modern Yangtze River. The analytical results of TSM and stable carbon isotopes are further confirmed by another independent tracer of sediment source, polycyclic aromatic hydrocarbons (PAHs). Five light mineral provinces in the SYS can be identified and they indicate inhomogeneity in sources and sedimentary environment. The modern shelf sedimentary processes in the SYS are controlled by shelf dynamic factors. The muddy depositional systems are produced in the shelf low-energy environments, which are controlled by some meso-scale cyclonic eddies (cold eddies) in the central SYS and the area southwest of the Cheju Island. On the contrary, an anticyclonic muddy depositional system (warm eddy sediment) appears in the southeast of the SYS (the area northwest of the Cheju Island). In this study, we give the cyclonic and anticyclonic eddy sedimentation patterns.

• 한국해양공학회지
• /
• 제33권6호
• /
• pp.564-572
• /
• 2019

Numerical simulation of the sediment by the Delft3d model was conducted to examine the changes in the sediment budget transport caused by long-term wave changes at the Maengbang beach. Representative waves were generated with input reduction tools using NOAA NCEP wave data for about 40 years, i.e., from January 1979 to May 2019. To determine the adequacy of the model, wave and depth changes were compared and verified using wave and depth data observed for about 23 months beginning in March 2017. As a result of the error analysis, the bias was 0.05 and the root mean square error was 0.23, which indicated that the numerical wave results were satisfactory. Also, the observed change in depth and numerical result were similar. In addition, to examine the effect due to long-term changes in the waves, the NOAA wave data classified into each of the representative wave grades, and then the annual trend of the representative wave was analyzed. After deciding the weight of each wave class considering the changed wave environment in 2100, the amounts of sedimentation, deposition, and the sediment transport budget were reviewed for the same period. The results indicated that the sedimentation pattern did not change significantly compared to the current state, and the amount of the local sediment budget shown in the present state was slightly less. And there has been a local increase in the number of sediment budget transport, but there is no significant difference in the net and amount of sediment movements.

• Environmental Engineering Research
• /
• 제15권1호
• /
• pp.41-48
• /
• 2010

This paper describes the influence of nutrient salts eluted from the bottom of a closed water area where polluted sediment has been deposited by inflowing river water. The elution pattern was monitored at our experimental facility. Both the sediment pore water and water above the bottom were sampled using a dialyzer sampler (peeper). The pore water of the eutrophicated sediment contained a large amount of nutrient salts, and the effect of elution was confined to a limited area of the bottom surface. The nutrient concentration of the sediment pore water was closely related to both the water temperature and dissolved oxygen (DO) concentration. The eluted nutrients from the sediment provided a source for phytoplankton and algae growth. This experimental data indicated that the water quality of the surface was not directly connected to the eluted nutrient salts, while it was indirectly affected by the total ecosystem, including all the organisms within an area and their environment.