• Journal of Korea Water Resources Association
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• v.45 no.9
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• pp.915-928
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• 2012

Han River estuary (HRE) is located at the middle of the western coast of Korea, and tidal currents were measured at 4 stations in this estuary during the winter season, and previously observed tide data was analyzed. The results of amplitude ratio of $M_4/M_2$ showed that increasing upward to estuary in the HRE. Tide harmonic constants of relative phase $2M_2-M_4$ represent flood dominance, with under 180 degree. But this method has a limit of analysis that typically based on the non-linear distortion of the tidal current in tidal lagoon system where freshwater discharge is assumed to be relatively small. The results of statistically tidal current data indicated that ebb current velocity would be great unlike tide data. Ebb and flood duration time is calculated by slack time of tidal current showed that ebb duration time is longer than flood. The results of correlation of analysis show high value (0.9) between tidal current stations from Incheon harbor to north entrance of Yeomha channel. We reconstructed to find the reasons for the features of ebb dominance the results of harmonic analysis. As major component ($M_2$) in combination with shallow water component ($M_4$), the tidal curve was presented flood dominance that has a flood current is stronger. However, these curve were changed to ebb dominance add up the non-harmonic components that had ebb direction flow by calculated tidally averaged current. The characteristic of enhancement on ebb is showed around the Yeomha channel in the HRE, because averaged flow which acts seaward such as long-term tidal current components due to non-linear effect and freshwater which overcome the flood current.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.3
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• pp.321-331
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• 2008

A model has been constructed in this study for the investigation of physical characteristics of the Gyeonggi Bay and Han River estuary. MIKE 21 HD (HyDrodynamics) has been used for the uncertainty analysis of the tide of the Gyeonngi Bay and Han River estuary. A total of 15 model experiments have been performed for the hydrodynamic parts and the analysis of results have been made in terms of RMSD (Root-mean square deviation) which has been frequently employed in the suitability analysis of hydrological data since the introduction by NERC(1975), U.K. A smaller value of RMSD indicates the more suitability of a parameter to the model. Analysis of the hydrodynamic results has shown that RMSD of the mean tidal range has the largest value of 0.1148 at Yeomha channel while has the smallest value of 0.0400 at Yeonphyong-do, indicating that the uncertainty in the mean tidal range on near-shore side is larger than that of offshore side. Experiment with reduced water depth by 10% has produced a most significant increase in RMSD. It is therefore implied that the model response changes more sensitively to water depth rather than grid sizes, open boundary forcing and river discharge.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.257-268
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• 2012

The EFDC model with find grid resolution system connecting the Gyeong-Gi bay and Han River estuary was constructed to study on spring-neap variability of net volume transport at each channel of the Han River estuary. The simulation time of numerical model is 124 days from May to August, 2009 with freshwater discharge at Han, Imjin and Yeseong River. The calibration and verification of model results was confirmed using harmonic components of water level and tidal current. The net volume transport was calculated during 30 days with normal freshwater conditions at Seokmo channel and Yeomha channel around Ganghwado. The ebbing net volume transport of 44% and 56% is drained into Gyeong-Gi bay through Yeomha and Seokmo channel, respectively. The ebbing net volume transport nearby Seodo at Yeomha channel convergence flooding net volume transport at Incheon harbor, and drain (westward direction) through channel of tidal flat between Ganghwado and Yeongjongdo to the Gyeong-Gi bay. The averaged net volume transport during 4 tidal cycles was compared to variation of spring-neap periods of the Yeomha channel. The convergence position is moved up- and down-ward according to spring-neap variability. The movement of the convergence zone is appeared because 1) increasing of discharged rate tidal flat channel between Ganghwado and Yeongjongdo at the spring period, 2) The growth of barotropic forcing with downward direction at the spring tide, and 3) The strength of the baroclinic pressure gradient is greater than spring with mixing processes.

• Journal of the Korean association of regional geographers
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• v.13 no.4
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• pp.454-460
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• 2007

Korean War resulted in the fact that Demilitarized Zone (DMZ) on the neck of Korean peninsular was totally forgotten by people for more than half a century. But recently, as the concern in this DMZ has been rising inside and outside of Korea, the researches on this subject have been gradually quickening. However, the practical studies about spatial extent of DMZ are very feeble. Even the analysis of the previous studies shows that the most of researches had mistakes in the spatial description of MDL and DMZ, neutral territory of Han River estuary, and NLL. In this study the length of MDL, stretching till the estuary of western Lim- Jin River in Myung-Ho Ri of Goseong region on East Coast, was measured to be about Z38km (l48miles); the area of corresponding DMZ was proved to be approximately $903.8km^2$ ($907.3km^2$ in the previous studies). Such results show that it is necessary to decide the terms for calling the space dividing North and South Korea, similarly to "155-mile truce line".

• Journal of Wetlands Research
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• v.10 no.2
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• pp.173-178
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• 2008

The habitat composition in the Han-river estuary, where white-naped crane(Grus vipio; endangered migrating bird) spend winter, was analysed by the geographic information system(GIS). And the habitat use pattern of white-naped crane collected by satellite tracking method was analysed. The % composition of seven habitat categories of land cover classification was compared for the buffers of radii 100 m, 200 m, 500 m, and 1 km, respectively, around the white-naped crane position point(n=228), and the statistical analysis was done using chi-square test. The results showed no selective use of habitat area by white-naped crane in the buffers of 100 m, 200 m and 500 m, but showed clear selection of habitat use (p < 0.05) in the case of 1 km buffer.

• Journal of Korea Spatial Information System Society
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• v.10 no.4
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• pp.77-88
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• 2008

There has been growing demands to manage the water quality of west coastal region due to the large scale urbanization along the coastal zone, the possibility of application of TMDL(Total Maximum Daily Loadings) to Han river, and the natural disaster such as oil spill incident in Taean, Chungnam. However, no system has been developed for such purposes. In this background, the demand of GIS based effective water quality management has been increased to monitor water quality environment and propose best management alternatives for Han river and Kyeonggi bay. This study mainly focused on the development of integrated water quality management system for Han river bas in and its estuary are a connected to Kyeonggi bay to support integrated water quality management and its plan. Integration was made based on GIS by spatial linking between water quality attributes and location information. A GIS DB was built to estimate the amount of generated and discharged water pollutants according to TMDL technical guide and it included input data to use two different water quality models--W ASP7 for Han river and EFDC for coastal area--to forecast water quality and to suggest BMP(Best management Practices). The results of BOD, TN, and TP from WASP7 were used as the input to run EFDC. Based on the study results, some critical areas which have relatively higher pollutant loadings were identified, and it was also identified that the locations discharging water pollutant loadings to river and seasonal factor affected water quality. And the relationship of water quality between river and its estuary area was quantitatively verified. The results showed that GIS based integrated system could be used as a tool for estimating status-quo of water quality and proposing economically effective BMPs to mitigate water pollution. Further studies need to be made for improving system's capabilities such as adding decision making function as well as cost-benefit analysis, etc. Also, the concrete methodology for water quality management using the system need to be developed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.735-749
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• 2018

In this study, one studied the principal factors and water-quality components that determine the concentration of chemical oxygen demand (COD) in seawater in estuaries, such as the Han, Geum, Youngsan, Seomjin, and Nakdong rivers in Korea. The principal factors determining the concentration of COD in seawater indicated by the principal component analysis were salinity, exogenous origin and autochthonous resources based on chlorophyll-a. Moreover, organic matter in the submarine sediment layer also had a secondary effect. Regression slope assessed the contribution of water-quality components to determine the concentration of COD in the estuary. One found that the effect of salinity on the overall survey was significant. Moreover, the effect of chlorophyll-a was also appeared in April and August. In each estuary, the most significant contribution factor was chlorophyll-a in the Nakdong River and salinity in the Han and Yongsan rivers. The contribution of salinity and chlorophyll-a were found to be the largest in the Geum River. The salinity and chlorophyll-a in the Seomjin River showed a low contribution.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.244-248
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• 2008

홍수량산정과 관련하여 국내 실무에서 어려움을 겪는 가장 큰 문제는 설계강우의 결정이다. 설계강우와 관련하여 세부적으로 살펴보면 크게 강우의 시간분포(예를 들면 Huff, Mononobe, 교호블록 등), 강우의 공간분포(ARF 적용 등)의 두가지 문제로 집약될 수 있다. 본 논문에서는 강우의 시간분포와 공간분포에 관련된 문제를 동시에 해결할 수 있는 방법으로 교호블록형 이동설계강우에 대한 적용 방법을 제안하고 그 적용성을 검토하였다. 본 연구에서는 국내에서 연구된 강우의 이동속도와 여름철 저기압기단과 태풍의 이동속도 등을 감안하고 나아가 표준화된 방법으로서 적용의 용이성 등을 고려하여 강우의 이동속도 $\upsilonv\;=\;10km/hr$, $\Delta\;=\;10km$ 간격으로 직사각형 띠 형태로 연결되는 이동강우를 채택하였다. 강우의 이동방향은 서$\rightarrow$동, 남$\rightarrow$북, 남서$\rightarrow$북동의 3가지 방향을 기준하였다. 유역특성 이동강우 3가지(서$\rightarrow$동, 남$\rightarrow$북, 남서$\rightarrow$북동)와 정체강우 2가지(유역평균, 유역특성) 등 총 5가지 경우에 대하여 100년 빈도 48시간 설계강우를 한강유역의 분포형 강우-유출 모형에 적용하여 그 결과를 분석하여 다음과 같은 결론을 얻었다. (1) 정체강우에 있어서 유역평균강우와 유역특성강우에 대한 홍수량 비교를 통하여 해당 유역의 홍수량과 강우량과의 관계를 판단할 수 있었다. 충주댐유역의 경우 한강유역 전체에 대한 평균 100년 빈도 강우가 내린다면 23,000cms까지도 발생할 수 있으나 충주댐유역 100년 빈도에 해당하는 강우량으로는 18,000cms 정도의 홍수량이 발생하여 상대적으로 강우량이 적은 지역으로 나타났다. 반면에 임진강하류부는 한강유역평균강우 보다 더 많은 강우량이 내림으로 인하여 홍수량이 증가하는 유역임을 알 수 있었다. (2) 이동설계강우에 대하여 분석한 결과 유역이 매우 크거나 매우 작으면 강우의 이동방향에 대한 영향이 상대적으로 감소해가는 반면에 중규모 유역에서 상대적으로 영향이 크게 나타났다. 한강하구와 같은 대유역의 경우 여러 방향의 유역들이 유출에 기여하기 때문에 강우의 이동방향에 대한 영향이 상쇄되기 때문으로 분석되었다. 반면에 매우 작은 소유역의 경우는 전체 유역이 단일 강우강도의 영향권에 놓이게 되므로 이동방향의 영향이 나타나지 않는 것으로 나타났다. (3) 정체설계강우와 이동설계강우의 비교를 통하여 한강하구와 같은 대유역의 이동강우에 대한 ARF 효과를 간접 측정할 수 있었다. (4) 정체설계강우 보다 이동설계강우가 오히려 더 큰 첨두홍수량을 발생시키는 유역들이 있었다. 이와 같은 수문현상은 기존 정체형 설계강우로는 분석이 어려운 현상으로서 강우와 유역특성에 대한 보다 심층적인 연구 필용성을 제기하고 있다.

• Journal of Wetlands Research
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• v.26 no.3
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• pp.285-297
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• 2024

This study, conducted in Geolpo-dong and Gamjeong-dong near Gimpo-Hangang New Town, examines an area adjacent to the Han River estuary, a major wintering ground for migratory birds. Over 59 surveys from October 2015 to March 2022 in four representative rice fields (sites A-D) recorded 44,942 individuals from 32 genera and 72 species. Site D, a large area near the Han River, exhibited high species diversity. Despite lower diversity in areas under development (sites A, B, C), ongoing species influx and utilization persist. The study focuses on Anser fabalis, a species predominantly utilizing rice fields, and identified their distribution characteristics. The analysis revealed 162 instances of population influx, with over a 30-fold increase observed across 39 surveys conducted over a 30-month period (October to March, '15~'22). The area, a key wintering site for migratory birds of Janghang Wetland, about 5 km from feeding sites, is heavily utilized by migratory geese, indicating the region's high value considering migration distance and anticipated continuous bird influx despite urban expansion. Therefore, future developments should preserve ecological corridors and connected stepping stone habitats to not only preserve existing habitats but to secure alternative feeding sites, ensuring smooth movements and mitigating habitat loss.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.274-294
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• 2007

The most reasonable method of counting the number of the estuaries in Korea may be counting the number of streams flowing into the sea. The number counting of the streams should be carried out based on the river classes (National River, Regional 1st Class River and Regional 2nd Class River) given by the River Act. The National River scale estuaries are totaled to thirteen, i.e. Han River(including Imjin River), Anseongcheon, Sapgyocheon, Geum River, Mankyeong River, Dongjin River, Yeoungsan River, Tamjin River, Seomjin River, Gawhacheon, Nakdong River(including West Nakdong River), Taewha River, and Hyeongsan River estuaries. The Regional 1st Class River scale estuaries are counted as four, i.e. Yeoungdeok Osipcheon, Samcheok Osipcheon, Gangneung Namdaecheon, and Yangyang Namdaecheon. While, the Regional 2nd Class River estuaries are arranged as the Province and counted as total 444; Jeonnam, Gyeongnam, Chungnam, Jeju Province have the 108, 94, 52, and 35 estuaries, respectively. The counted estuary numbers, however, can be slightly increased/decreased on what references are applied, e.g. whether or not including the streams lost estuary functions by the sea-dike construction or integrated nearby streams, and so on.