• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.433-433
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• 2011

수자원 계획 및 관리를 위한 지표 자료로서 일유량은 매우 유용하기 때문에 정확한 일유량 산정의 문제는 매우 중요하다. 그러나 우리나라의 경우 조석이나 배수 갑문 혹은 보 등에 의한 배수 영향으로 인해 수위-유량관계곡선식만으로 정상적인 유량산정이 어려운 지점이 다수 존재한다. 특히, 한강대교 지점과 같이 조석영향 구간에서 수위-유량관계곡선식에 의해 산정된 일유량은 자료에 대한 곡선식의 적합도 문제로 그 정확도가 매우 낮았다. 최근 자동유량측정에 의해 시간단위 이하의 실시간 유량이 생산되고 있고 이를 이용하여 일유량을 환산하고 있어 과거에 비해 보다 정확한 일유량 산정이 가능해 졌다. 그러나 신뢰도 있는 일유량을 안정적으로 제공하기 위해서는 보다 다양한 조건을 고려한 비교 검증 연구가 요구되는 실정이다. 이러한 배경에서 본 연구에서는 한강대교 지점과 같이 조석영향을 받는 지점의 일유량 산정방법 및 산정개념에 따른 유황의 차이와 적정성을 평가하여 보았다. 각 산정방법 및 산정개념 별로 산정된 일유량을 통해 유황을 산정하여 한강대교 지점의 일유량 산정방법에 대한 적정성을 평가하고 적절한 유황산정을 위한 목적별 대안을 제시하였다. 산정방법 별로는 기존의 수위-유량관계 곡선식으로 변환된 자료, 자동유량측정자료, 그리고 자동유량측정자료에서 조석성분을 제거한 순수 유출성분자료를 이용하여 일유량을 산정하였고, 이를 이용하여 산정된 유황에 대한 비교 분석을 실시하였다. 수위-유량관계곡선식에 의한 일유량은 수문조사연보의 자료를 이용하였고 자동유량자료를 이용한 일유량은 시자료를 평균하여 일유량으로 환산하는 방법을 사용하였다. 자동유량 자료에서 조석성분을 제거한 순수 유출성분의 추출은 웨이블릿 변환(wavelet transform)을 이용하였다. 각 방법별로 산정된 일유량을 비교한 결과 수위-유량관계곡선식에 의해 산정된 일유량이 자동 유량자료로 산정된 일유량에 비해 전반적으로 크게 나타났고, 2009년 한해 동안의 유출용적을 비교해 본 결과 18%정도 더 크게 산정되었다. 산정개념에 따른 비교에서는 조석성분 유량의 유효성 여부에 따른 유황을 비교하였으며, 조석성분 유량도 실효적 유량으로 간주한 경우 이론적 확률 분포형에 적합시켜 산정한 평균 갈수량은 15.7 ��/s(동절기 이상 거동기간인 2009년 11월 17일-12월 12일 기간을 제외하고 산정된 결과이나 불확실성은 잔존)에서 $53.2m^3/s$로 증가하였다. 따라서 유지유량의 목적상 경관용수나 생태용수가 중요한 지점으로 조석성분 유량이 이에 유효하다면, 유황산정을 위한 한강대교 지점의 일유량 산정방법은 다양한 목적에 비추어 추가적인 분석 검토가 필요할 것으로 판단된다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.255-265
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• 2013

In the coastal region of Korea, historical tide harmonic constants were collected. Long-term tides and short-term tides observed by the KHOA were analyzed by a tide harmonic analysis method. Based on the harmonic constants, tidal characteristics such as tide asymmetry in Korean coastal waters were investigated. The harmonic constants obtained from the long-term tide data in the western coast have been used to show the relation between tide variation and reclamation project. $M_2$ amplitudes in the western coast have been decreased and $M_2$ phases were faster. $M_4$ amplitudes also were reduced and $M_4$ phases were faster in overall. In Mokpo and Kunsan tidal nonlinearity is relatively conspicuous. Overall, non-linearity of tidal currents is higher in the tidal channels flowing fast. The tidal non-linearity has increased by the development projects including large reclamation. The flood dominant characteristic in the northern and central part of Korean western coastal waters and the ebb dominant characteristic in the southern part have been intensified. The construction of Saemangeum sea dike has significantly changed the tidal characteristic in Korean western coastal waters.

• Journal of Marine Life Science
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• v.5 no.1
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• pp.25-33
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• 2020

The Asan Bay, which has semi-diurnal tide with macro-tidal range, is affected by both freshwater discharge from the sluice gates in the sea dikes and tidal seawater inputs from the Yellow sea. Understanding water quality change in response to tides is important since tides can impact the short-term variations in physical and chemical water properties as well as the response of biological properties. The diel variations in water quality were seasonally investigated at 2 hour intervals from a fixed station in the Asan Bay. In the results, water temperature and salinity consistently fluctuated in phase or out of phase with tidal height. Especially salinity was positively correlated with tidal height. The concentrations of total suspended solids were higher in the bottom water than in the surface and fluctuated greatly over the tidal cycle recording higher values at low tide than at high tide. Nitrite+nitrate levels also fluctuated out of phase with tidal height and correlated negatively with tidal height. Other nutrients also showed a similar pattern. The pattern was distinct in July when freshwater was discharged before the field sampling. The concentrations of organic materials, total nitrogen and total phosphorus greatly fluctuated over the tidal cycle and were generally out of phase with tidal height. Most materials except particulate organic forms were correlated with salinity indicating that freshwater inputs were sources for the materials similarly to the dissolved inorganic nutrients. The results suggest that water quality (except dissolved oxygen and pH) and nutrients including organic materials was largely affected by tides in the Asan Bay.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.6
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• pp.222-232
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• 2022

In this study we investigated the characteristics of long-term tidal constituents based on 30 tidal gauge data along the coasts of Korea and its the effects on total water level (TWL) forecasts. The results show that the solar annual (Sa) and semiannual (Ssa) tides were dominant among long-term tidal constituents, and they are relatively large in western coast of Korea peninsula. To investigate the effect of long-term tidal constituents on TWL forecasts, we produced predicted tides in 2021 with and without long-term tidal constituents. The TWL forecasts with and without long-term tidal constituents are then calculated by adding surge forecasts into predicted tides. Comparing with the TWL without long-term tidal constituents, the results with long-term tidal constituents reveals small bias in summer and relatively large negative bias in winter. It is concluded that the large error found in winter generally caused by double-counting of meteorological factors in predicted tides and surge forecasts. The predicted surge for 2021 based on the harmonic analysis shows seasonality, and it reduces the large negative bias shown in winter when it subtracted from the TWL forecasts with long-term tidal constituents.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.320-324
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• 2008

In order to identify the change of tidal characteristics on average in the Asan Bay due to the construction of the Hwaong (Namyang Bay) tidal barrier (HTB), the tide data at Pyongtack (PT) and Anheung (AH) for the periods from 1993 to 2006 were analyzed using the harmonic analysis method, and major and shallow water tidal constituents were compared. The semidiurnal tidal amplitudes at PT increased while those at AH decreased after the tidal barrier construction. In particular, the amplitudes at PT increased abruptly during the period of $2002{\sim}2003$ when HTB was completed. On the other hand, the amplitudes of the diurnal tides at PT and AH showed minimal change. This suggests that the tidal characteristics change in the Asan Bay may be related to the construction of HTB. The cause of this change is different from either blocking the tidal wave propagation by the Keum River tidal barrier or removing 'choking effect' by the Yeongsan River tidal barrier. The $M_4/M_2$ ratio increased and their phase difference decreased after the completion of HTB. Accordingly, these changes may result in increase of tidal range, decrease of the flood duration and increase of the flood current velocity, inducing more sediments into the Asan Bay.

• Water for future
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• v.26 no.2
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• pp.67-77
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• 1993

The increased water level caused by tidal motion at Indokyo is analyzed by the NETWORK model. The tidal effect is studied for 3 real floods in 1990 and 8 classified hypothetical floods in which the peak discharges are in the range of 2, 000-20, 000CMS. The result of numerical simulation shows that the tidal effect is decreased as the flood is increased. The surged level is 50cm when the flood discharge is 2, 000CMS, showing that its effect is considerable. However it shows only 9cm when the discharge is 7, 000CMS which corresponds to 4.5cm of standard flood level of MOC. Therefore, so it may be possible to neglect the influence of the tidal fluctuation when the peak discharge of a flood is bigger than 7, 000CMS.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.377-381
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• 2011

지구는 지속적으로 변화하는 동력학적 시스템이며, 지표면 형상 및 지구 내부의 질량분포도 계속 변화하고 있다. 지구시스템의 질량재분배 과정에서 발생되는 밀도 차이는 중력장의 미세한 변이를 초래한다. 미 항공우주센터(NASA)와 독일 국립 항공우주연구센터(DLR)에서 공동으로 개발한 GRACE (Gravity Recovery And Climate Experiment) 인공위성은 지구의 중력장을 측정하는 위성으로, 2002년부터 현재까지 9년 동안 활동해왔다. 본 연구에서는 한반도(북위 $37.5^{\circ}\sim41.5^{\circ}$, 동경 $125.5^{\circ}\sim130.5^{\circ}$)의 월평균 수자원변화량(TWSC: Terrestrial Water Storage Change)을 산정하기 위해 미국 텍사스대학교 공간연구센터(CSR)에서 가우시안 필터링을 통해 구면조화함수의 계수 형태로 제공된 총 94개월(2002 년 8월~2010년 6월)의 자료(Level-2)를 이용하였다. Level-2 자료는 해양조석, 고체지구조석 및 지구자전으로 인한 극조석 등 조석의 영향과 대기와 해양의 변동성으로 인한 비조석 영향을 보정한 것이다. 이렇게 산정한 TWSC를 수자원관리정보시스템(WAMIS)과 전지구지표동계화시스템(GLDAS)을 통해 제공되는 자료와 비교 분석하였다. 본 연구를 통해 GRACE 중력장 자료가 수자원총량의 산정과 검증을 위한 대안으로 활용될 수 있음과, 수문요소의 불확실성을 낮출 수 있는 새로운 수문자료로의 활용 가능성을 확인하였다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.31-43
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• 1989

Tidal asymmetry and the associated sediment dynamics in the Keum River Estuary has been investigated from a numerical tidal model. Modeling efforts were focussed on the simulation of large drying sandflat exposed at the mouth of the Estuary and dynamic combination of two-dimensional estuary model and one-dimensional river model. Despite strong frictional attenuation within the estuary, the M4 tides reach significant amplitude, resulting in strong tidal distortion. Model results show that the asymmetry over the area exhibit more intense flood flows transport than do less intense ebb flows of longer duration. This causes filling of the estuary as evidenced by large sandflats spread over the inner area. The spatial distribution of peak bottom stress computed from the tidal model suggest that present tidal sedimentation regime may be altered significantly, especially in the approach channel to outer Kunsan port and downstream part of the dike, due to the construction of cross-channel barrier.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.1
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• pp.1-15
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• 2007

In this study 8 nodes parallel linux cluster system is constructed and tested for the evaluation of computational efficiency and reliability of the Yellow Sea tidal hydrodynamics prior to compute storm surge inundation along the west coast of the Korean Peninsular. Computational efficiency increases up to 7 times based on NPB bench-marking test. Simulated results by pADCIRC on reproduction of the Yellow Sea tidal hydrodynamics resemble well with previous studies. According to model parameter tests, bottom friction coefficient, which should be appropriately represented shallow depth along the west coast, is essential factor in simulation.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.50-54
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• 1996

극치확률 모델과 더불어 최극해면분석에 이용되는 또 하나의 방법은 조석 및 비조석성분의 복합확률방법(joint probability method)으로 Pugh와 Vassie(1978)에 의해 제시되었다. 이 방법은 조석(tide)과 비조석성분(surge)이 통계적으로 독립적인 변수(statistically independent variable)로 취득될 수 있는 가를 일차적으로 분석한 후 해면의 확률분포를 조위분석함수(tidal probability distribution function)와 비조석성분분포함수(surge probability distribution function)의 복합으로서 산정하는 것이다. (중략)