• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2125-2129
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• 2007

본 연구에서는 영산강 하구언 배수갑문의 개방으로 대량의 담수가 방류될 경우 목포항 인근해역의 해수유동 변화와 이에 수반되는 부유물질/염분 농도의 시공간적인 변화를 파악하기 위해 방류조건과 확산성분별로 12가지의 계산 시나리오를 구성하고 MIKE21의 해수유동(HD)모듈과 오염 확산(AD)모듈을 이용하여 하구언 방류의 영향을 살펴보았다. 해수유동 모의결과, 배수갑문과의 거리에 따라 방류조건별로 수위와 유속이 최대 144.5cm, 175.6cm/sec까지 상승하였다. 특히 청계만 수역에서는 방류시기에 낙조시 유속이 최대 68.8cm/sec까지 감소해 방류에 따른 수위상승으로 낙조시 해수유출이 지체되는 것으로 판단된다. 부유물질 확산모의 결과, 목포 기준검조소를 기준으로 목포항 내부수역은 원활한 해수순환이 이루어지지 않아 각종 오염원 유입시 외해로 쉽게 확산되거나 희석되지 못하고 계속 정체되는 것으로 나타나 항내 오염이 심각하게 우려되며, 특히 연속적인 담수 방류와 방류량의 크기가 내부수역의 부유물질 농도 감소에 큰 영향을 미치는 것으로 판단됨에 따라 방류량이 작고 연속 방류가 행해지지 않는 비우기시의 오염은 더욱 심해질 것으로 판단된다. 방류조건별 염분농도 역시 방류량이 크고, 연속적인 담수 방류가 행해질 경우 농도가도 크게 감소하며 확산면적도 증가하였다.

• Korean Journal of Environmental Biology
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• v.29 no.3
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• pp.212-224
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• 2011

The Yeongsan River estuary, located in the south west coast, was a typical estuary before a dike was constructed in December 1981. After the construction, the water quality and plankton communities are expected to change. We investigated the change of phytoplankton community and environmental properties in the Yeongsan River estuary by comparing the data collected recently with the results reported before and/or shortly after the construction. Concentrations of $NH_4$-N were significantly increased in the freshwater zone. Concentrations of DO at the surface, $NO_2+NO_3$ and $NH_4$-N were increased while the concentrations of $PO_4$ at the surface were decreased in the seawater zone. The number of green algae species was decreased in the freshwater zone. The number of diatom species was decreased while the numbers of green algae and dinoflagellates were increased in the seawater zone. This study can provide information for better management of the Yeongsan River estuary since no comparison study has been documented between the phytoplankton community before and after the construction of the dike in the estuary.

• Water for future
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• v.11 no.2
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• pp.17-22
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• 1978

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.205-214
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• 2013

In Yeongsan River estuary, located in the southern West Coast, a dike was constructed in December 1981. After the construction of a dike, discharge mechanism of fresh water has been changed, the water quality and chlorophyll-a are expected to be influenced by fresh water discharge. We investigated temporal and spatial variations and long-term trend of phytoplankton biomass (chlorophyll-a) and environmental factors. The concentrations of nutrient and chlorophyll-a were generally high in summer and the concentrations were increased toward downstream. Surface/bottom salinity difference was negatively correlated with salinity in surface water but positively with nutrient and chlorophyll-a. TN, TP and DIN concentrations were generally increased over 10 years. This study can provide information for better management of water quality for Youngsan River estuary.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.273-284
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• 2007

The spatial and temporal zooplankton dynamics were examined along ca. 100-km section of the middle to lower Seomjin River (without estuary dam in river mouth) and Youngsan River (with estuary dam in river mouth) systems during study periods (2004. Nov.${\sim}$2006. Aug.) based on a monthly sampling intervals. The spatial variation of zooplankton biomass at both river ecosystems was distinct. There was considerable longitudinal variation in total zooplankton abundance in Youngsan R. stretch. The increase in total zooplankton abundance were observed along the longitudinal stretch toward the estuary dam. In contrast, there were not statistically significant longitudinal differences in total zooplankton abundance in Seomjin R. stretch. In Youngsan R. stretch, average abundance of total zooplankton (average ranges: $199{\sim}817$ Ind. $L^{-1}$ at 3 sampling sites, n=20) were nearly $4{\sim}60$ fold higher than that of Seomjin R. stretch (average ranges: $12{\sim}43$ Ind. $L^{-1}$ at 4 sampling sites, n=20). Relative abundance of rotifers (over 80% of total zooplankton abundance) at the whole sampling sites in Youngsan R. stretch were Much higher than that of the Seomjin R. stretch. The most abundant rotifers were Polyarthra spp., Brachionus spp., Colurella spp., and Keratella spp. at the both river ecosystems. In Seomjin R. stretch, copepods carbon biomass sharply increased toward in river mouth (over 40% of total zooplankton carbon biomass). Average ranges of total zooplankton filtering rates for phytoplankton at both river ecosystems varied from 21.2 to 92.9 mL $L^{-1}\;D^{-1}$ in Youngsan R. stretch and from 2.1 to 2.6 mL $L^{-1}\;D^{-1}$ in Seomjin R. stretch. Considering the zooplankton filtering rates, zooplankton as grazers of phytoplankton in Youngsan R. stretch seemed to play the more important role in planktonic food web than that of the Seomjin R. stretch.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.3
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• pp.139-148
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• 2012

The short-term variation of salinity and temperature in a dyked estuarine environment is mainly controlled by the freshwater discharge from the dyke. We examined the distribution of salinity and temperature by the freshwater discharge in the Yeongsan River estuary using the CTD data obtained from 8 stations through three surveys in June (weak discharge) and August (intensive discharge), 2010. During the weak discharge in June, the surface salinity showed 30-32.5 psu and its horizontal gradient was relatively high around Goha-do (0.25~0.32 psu/km). On the other hand, the salinity of the bottom layer was almost constant in the range of 33 psu. Water temperature ranged $19{\sim}21^{\circ}C$ and displayed higher gradient in north-south direction than the gradient of east-west direction. During the intensive freshwater discharge on August 12, the salinity dropped to 9~26 psu. The maximum horizontal gradient of surface salinity reached 3.8 psu/km in the north of Goha-do where the strong salinity front was formed, and the horizontal salinity gradient of bottom layer was 0.28 psu/km. The horizontal gradient of water temperature was $-0.45^{\circ}C/km$ in the surface and $-0.12^{\circ}C/km$ in the bottom with high surface temperature near the dyke and decreasing gradually to the river mouth. After 3 days of the intensive discharge ($3^{rd}$ survey), the surface salinity increased to 22~26 psu. However, there still existed relatively high horizontal gradient around Goha-do. In the mean time, the bottom salinity decreased to 26.5~27.5 psu, but its gradient was not big as much as the surface gradient. According to time series of CTD profile near the dyke, the discharged fresh water jetted down temporarily and then recovered gradually with the recovering speed of 0.4 m/hour for the discharge case of $13{\times}10^6$ ton. Due to the combined effects of freshwater discharge and surface heating during the summer of 2010, the Yeongsan estuary, in general, underwent intensified vertical stratification, which in turn caused the inhibition of vertical mixing, especially inside area of estuary. Based on the spatial distribution of salinity and temperature, the Yeongsan estuary can be divided into three regions: the Goha-do area with strong horizontal gradient of salinity and temperature, inner estuary from Goha-do to the dyke with low salinity, and outer estuary from Goha-do to the coasts with relatively high salinity.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1991.06a
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• pp.37-44
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• 1991

영산강 하구언 방조제의 건설로 인한 항만 및 이의 인접해역 해면의 변화는 예상한 바 있으며 실제 여러개소에서 월 2회정도의 주기로 목포 구항부근 상업지역에서 해면상승에 따라 주기적으로 침수되는 현상이 나타나고 있다 목포항의 영산강 하구언 방조제 조성으로 인한 조류성분중 최고기록을 가진 수로에서는 6kts 정도로 감소된 것으로 보고되고 있으나 주위자연환경 변화에 따른 수면 상승 및 해수면의 주기적인 변화 등에 대한 상세한 언급 및 깊이 있는 분석은 회피되어왔다. 수자원의 효율적관리를 위해 하구언 방조제는 이미 건설되었고 앞으로 대규모의 항만개발과 대불산업단지조성을 위해 추가 3개의 만입해안해역에 댐으로 해역을 막아 매립공사를 추진하고 있다 그러나 이 지역에 대한 분석은 타당성의 여부만을 강조한 상업적 용역이 이루어지고 있고 장래 개발에 대해 학술적이고 실질적인 문제점 추출과 해결방아네 대해서는 무시하거나 경시한 바가 많다 더구나 태풍 저기압 등과 같은 자연재해를 고려한 분석은 시도되지 못하고 있다 따라서 개발전후의 현상에 대한 상세한 자료 및 현장 조사와 극한 상태를 고려하여 개발에 따른 수위상승 부진동, 조류 수질등 이해역의 변화요소를 수집하고 분석하며 과학적 접근방법에 기초를 둔 수치모델의 실험을 포함하여 현장관측 및 측정자료를 검증하는 것이 필수적이라고 사료되어 종합분석의 한단계로 여기서는 하구언 및 하구간척(Land Reclamatic of Estuary barren)으로 해역축소에 따른 해면변화의 실제현상을 조사하여 정리하고 이를 수치모델을 통해 시뮬레이션하여 보았다 이는 종합개발의 좋은 기초자료로 이용됨은 물론이로 이지역의 개발에 기여할 것으로본다.적절하게 가정된 지반의 응력-변형률 관계와 간극수압특성에 의하여 고려되었다. 그 결과 응력 및 변위가 심하게 발생하는 지역은 황색 점토층이었으며 이로부터 황색 점토층에서 부터 파괴면이 생성되어 다른 지역으로 전파되었음을 유추할 수 있었다.form trap with 2.88[eV] deep of injected space charge from the chathode in the crystaline regions. The origin of ${\alpha}$$_2$ peak was regarded as the detrapping process of ions trapped with 0.9[eV] deep originated from impurity-ion remained in the specimen during production process of the material, in the crystalline regions. The origin of ${\beta}$ peak was concluded to be due to the depolarization process of "C=0"dipole with the activation energy of 0.75[eV] in the amorphous regions. The origin of ${\gamma}$ peak was responsible to the process combined with the depolarization of "CH$_3$", chain segment, with the activation energy of ca

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.46-56
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• 2017

The Youngsan River estuary was physically changed by the construction of a sea embankment at near the mouth of estuary. Weirs were also constructed recently in the freshwater zone and it was reported that algal blooms occur more frequently. The freshwater introduced into saltwater zone from sluice gates of the embankment affects water quality but it has not been addressed that how the freshwater inputs influence the health of marine ecosystem. In this study, we used the data of water properties and phytoplankton communities collected at three stations for 4 days including before the freshwater discharge, during the discharge and after 1 and 2 days of discharge events. WQI(water quality index), TRIX (trophic status index) and P-IBI(phytoplankton index of biotic integrity) were used to evaluate the ecosystem health and long-term data were also utilized to determine the criteria for P-IBI. The results showed that grades of the ecosystem health assessed by the indices were low at the station near the gates and increased as downstream. However, the temporal pattern of grades was different depending on methods. Grades of WQI and TRIX decreased during the discharge and restored after the discharge whereas the grades of P-IBI decreased slightly even after the discharge. This suggests that P-IBI is more applicable to estuarine systems where experience extreme change of water properties than WQI and TRIX since P-IBI includes phytoplankton that can respond quickly to the change.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.123-123
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• 2023

하천이 바다와 만나는 하구(河口, estuary)지역은 조위의 영향을 강하게 받아 하천 수위의 낙폭이 크고, 하상(河床)의 변동 또한 심하다. 때문에 이러한 감조구간은 홍수위 산정에 있어서도 일반하천에 비해 보다 세심한 주의가 요구된다. 우리나라 4대강 중 한강을 제외한 낙동강, 금강 및 영산강은 하구언 설치로 인해 이미 하구로서의 기능을 상실한 상황이다. 반면 한강 하류 구간은 북한과의 접경지역이라는 지리적, 상황적 특수성으로 인해 하구언 설치가 불가능하였기에 지금까지 감조상태를 유지하고 있다(Park and Baek, 2017). 지금까지 계획홍수위 산정시 일반하천이든 감조하천이든 간에 그 고유의 특성을 고려치 않고 정상-부등류(steady-nonuniform flow) 모의를 하는 것이 일반적인 관례이었다. 하지만 2018년 개정된 하천설계기준에 따르면 감조하천 구간에서는 반드시 부정류(unsteady flow) 모의를 수행하도록 규정하고 있다. 이에 따라 2020년 고시된 한강(팔당댐~하구) 하천기본계획(변경) 보고서에는 부정류해석을 통한 홍수위 산정분이 수록되어 있다. 문제는 "한강하구는 서해조석의 영향을 받는 감조하천이기는 하나 계획홍수량 유하시 한강에 미치는 조위의 영향은 미미하므로..."라는 결론을 도출하면서 부정류해석 결과 대신 부등류해석 결과를 계획홍수위로 결정했다는 것이다. 본 연구에서는 한강의 종점 유도지점을 기점으로 조석을 하류단 경계조건으로 부여하는 부정류 해석을 수행하여 한강하천기본계획(2020)의 홍수위와 비교하였다. 그 결과 본 연구에서 산정한 홍수위가 하구에서부터 신곡수중보 하류구간까지는 하천기본계획의 그것과 상당한 차이를 보였다. 한강하류 구간은 계획홍수량 발생시에도 조석의 영향을 받는 감조구간이므로 고시된 계획홍수위의 재검토가 필요해 보인다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.218-224
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• 2001

Water movement in the Young San River Estuary where a sea dyke was constructed, was observed using anacoustic doppler profiler (ADP) and two TGPS buoys for 25 hours on 27-28 July 2000. Hydrographic observations were simultaneously taken using CTD to understand the characteristic of the spacial structure of temperature and salinity. A large quantity of fresh water was discharged from the sea dyke on 26 July 2000. The observation period fell on neap tide. The amplitude of the tidal elevation and the maximum velocity of the tidal current were about 4 m and 12 cm/sec respectively. The water movement at the surface layer is mainly controlled by wind, and those at the other layers are controlled by semidiurnal tide. The low salinity water less than 22 psu was observed along the northern part during the early observation period while southerly wind prevails. The less saline water moves westward and finally leaves the estuary by easterly wind early on the second day. We can divide the vertical structure into four layers by hydrography and current structure. Mean velocity structure shows that relatively less saline waters at the surface and the middle layer move seaward, and the waters at the upper and the bottom layers move landward. It is thought that the intermittent discharge of river water from the sea dyke makes vertical structure of four layers.