• Title/Summary/Keyword: Tidal level prediction

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Adaptive Sea Level Prediction Method Using Measured Data (관측치를 이용한 적응적 조위 예측 방법)

  • Park, Sang-Hyun
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.5
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    • pp.891-898
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    • 2017
  • Climate changes consistently cause coastal accidents such as coastal flooding, so the studies on monitoring the marine environments are progressing to prevent and reduce the damage from coastal accidents. In this paper, we propose a new method to estimate the sea level which can be applied to the tidal sensors to monitor the variation of sea level. Existing sea level models are very complicated and need a lot of tidal data, so they are not proper for tidal sensors. On the other hand, the proposed algorithm is very simple but precise since we use the measured data from the sensor to estimate the sea level value in short period such as one or two hours. It is shown by experimental results that the proposed method is simple but predicts the sea level accurately.

Numerical analysis of a tidal flow using quadtree grid (사면구조 격자를 이용한 조석흐름 수치모의)

  • Kim, Jong-Ho;Kim, Hyung-Jun;NamGung, Don;Cho, Yong-Sik
    • 한국방재학회:학술대회논문집
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    • 2007.02a
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    • pp.163-167
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    • 2007
  • For numerical analysis of a tidal flow, a two-dimensional hydrodynamic model is developed by solving the nonlinear shallow-water equations. The governing equations are discretized explicitly with a finite difference leap-frog scheme and a first-order upwind scheme on adaptive hierarchical quadtree grids. The developed model is verified by applying to prediction of tidal behaviors. The calculated tidal levels are compared to available field measurements. A very reasonable agreement is observed.

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Estimation of Hydraulic Characteristics and Prediction of Groundwater Level in the Eastern Coastal Aquifer of Jeju Island (제주도 동부 해안대수층의 수리특성 산정과 지하수위 예측)

  • Jo, Si-Beom;Jeon, Byung-Chil;Park, Eun-Gyu;Choi, Kwang-Jun;Song, Sung-Ho;Kim, Gi-Pyo
    • Journal of Environmental Science International
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    • v.23 no.4
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    • pp.661-672
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    • 2014
  • Due to tidal force, it is very difficult to estimate the hydraulic parameters of high permeable aquifer near coastal area in Jeju Island. Therefore, to eliminate the impact of tidal force from groundwater level and estimate the hydraulic properties, tidal response technique has been mainly studied. In this study we have extracted 38 tidal constituents from groundwater level and harmonic constants including frequency, amplitude, and phase of each constituent using T_TIDE subroutine which is used to estimate oceanic tidal constituents, and then we have estimated hydraulic diffusivity associated with amplitude attenuation factor(that is the ratio of groundwater level amplitude to sea level amplitude for each tidal constituent) and phase lag(that is phase difference between groundwater level and sea level for each constituent). Also using harmonic constants for each constituent, we made the sinusoidal wave and then we constructed the synthesized wave which linearly combined sinusoidal wave. Finally, we could get residuals(net groundwater level) which was excluded most of tidal influences by eliminating synthesized wave from raw groundwater level. As a result of comparing statistics for synthesized level and net groundwater level, we found that the statistics for net groundwater level was more insignificant than those of synthesized wave. Moreover, in case of coastal aquifer which the impact of tidal force is even more than those of other environmental factors such as rainfall and groundwater yield, it is possible to predict groundwater level using synthesized wave and regression analysis of residuals.

A Study on Precise Tide Prediction at the Nakdong River Estuary using Long-term Tidal Observation Data (장기조석관측 자료를 이용한 낙동강 하구 정밀조위 예측 연구)

  • Park, Byeong-Woo;Kim, Tae-Woo;Kang, Du Kee;Seo, Yongjae;Shin, Hyun-Suk
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.6
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    • pp.874-881
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    • 2022
  • Until 2016, before discussions on the restoration of brackish water of the Nakdong River Estuary started in earnest, the downstream water level was predicted using the data of existing tide level observatories (Busan and Gadeokdo) several kilometers away from the estuary. However, it was not easy to carry out the prediction due to the dif erence in tide level and phase. Therefore, this study was conducted to estimate tide prediction more accurately through tidal harmonic analysis using the measured water level affected by the tides in the offshore waters adjacent to the Nakdong River Estuary. As a research method, the storage status of observation data according to the period and abnormal data were checked at 10-minute intervals in the offshore sea area near the Nakdong River Estuary bank, and the observed and predicted tides were measured using TASK2000 (Tidal Analysis Software Kit) Package, a tidal harmonic analysis program. Regression analysis based on one-to-one comparison showed that the correlation between the two components was high correlation coef icient 0.9334. In predicting the tides for the current year, if possible, more accurate data can be obtained by harmonically analyzing one-year tide observation data from the previous year and performing tide prediction using the obtained harmonic constant. Based on this method, the predicted tide for 2022 was generated and it is being used in the calculation of seawater inflow for the restoration of brackish water of the Nakdong River Estuary.

Beach Erosion during Storm Surge Overlapped with Tide (조위변동을 고려한 폭풍해일시의 해안침식에 관한 연구)

  • 손창배
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.6 no.2
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    • pp.47-56
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    • 2000
  • This paper describes a simple prediction method of beach recession induced by storm surge. In order to evaluate the severest beach erosion, it is assumed that maximum beach recession occurs at the coming of storm surge overlapped with spring tide. Consequently, total surge lev디 becomes the sum of storm surge level and tidal range. Generally, storm surge level around Korea is small compared with tidal range. Therefore total surge can be expressed as the series of surges, which have same duration as tide. Through the case studies, the author Investigates correlation between tidal range, duration, wave condition, beach slope and beach recession.

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Topography in intertidal zone by satellite images

  • Kang, Yong-Q.
    • Proceedings of the KSRS Conference
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    • 2002.10a
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    • pp.664-669
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    • 2002
  • Intertidal zone (tidal flat) is a place which is sometimes dry and sometimes wet depending on the tidal rhythm. Direct measurement of topography in the intertidal zone is very difficult to be achieved. The interface between wet and dry parts in the tidal flat, which can be identified from near infrared band of satellite image, is a 'depth contour' which corresponds to the sea level at the time of satellite pass. Aquisition of topography data in tidal flat is possible by combining various techniques such as (1) identification of the interface between wet and dry parts, (2) GCP correction of satellite image, and (3) realtime prediction of sea level elevation at the time of satellite pass. The algorithm was successfully applied in obtaining topography (bathymetry) data in the intertidal zone of Asan Bay in the west coast of Korea from 26 satellite images. The method is expected to be very efficient in making bathymetry data base in the western and southern parts of Korea where tidal flats are well developed in wide regions.

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A Method for Improvement of Tide and Tidal Current Prediction Accuracy (조위 및 조류 예측 정확도의 개선 방법)

  • Jung, Tae-Sung
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.13 no.4
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    • pp.234-240
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    • 2010
  • In order to predict coastal environmental changes caused by coastal development and effectively manage marine environment, the exact information about water level changes and hydrodynamic circulation is essential. However, most of the environmental impact assessment has been using only limited tidal constituents in the numerical tide model to predict the real tide and tidal currents caused by the synthesis of many other tidal constituents, which causes an error in the environmental impact assessment. In this study, a method, which uses the limited tidal constituents at the offshore open boundaries and the observed tide at the inner or nearby point to predict the real tide in the model domain accurately, is suggested. Tidal and tidal currents predicted by the suggested method agreed well with the observations.

Prediction of water level in a tidal river using a deep-learning based LSTM model (딥러닝 기반 LSTM 모형을 이용한 감조하천 수위 예측)

  • Jung, Sungho;Cho, Hyoseob;Kim, Jeongyup;Lee, Giha
    • Journal of Korea Water Resources Association
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    • v.51 no.12
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    • pp.1207-1216
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    • 2018
  • Discharge or water level predictions at tidally affected river reaches are currently still a great challenge in hydrological practices. This research aims to predict water level of the tide dominated site, Jamsu bridge in the Han River downstream. Physics-based hydrodynamic approaches are sometimes not applicable for water level prediction in such a tidal river due to uncertainty sources like rainfall forecasting data. In this study, TensorFlow deep learning framework was used to build a deep neural network based LSTM model and its applications. The LSTM model was trained based on 3 data sets having 10-min temporal resolution: Paldang dam release, Jamsu bridge water level, predicted tidal level for 6 years (2011~2016) and then predict the water level time series given the six lead times: 1, 3, 6, 9, 12, 24 hours. The optimal hyper-parameters of LSTM model were set up as follows: 6 hidden layers number, 0.01 learning rate, 3000 iterations. In addition, we changed the key parameter of LSTM model, sequence length, ranging from 1 to 6 hours to test its affect to prediction results. The LSTM model with the 1 hr sequence length led to the best performing prediction results for the all cases. In particular, it resulted in very accurate prediction: RMSE (0.065 cm) and NSE (0.99) for the 1 hr lead time prediction case. However, as the lead time became longer, the RMSE increased from 0.08 m (1 hr lead time) to 0.28 m (24 hrs lead time) and the NSE decreased from 0.99 (1 hr lead time) to 0.74 (24 hrs lead time), respectively.

Tidal Level Prediction of Busan Port using Long Short-Term Memory (Long Short-Term Memory를 이용한 부산항 조위 예측)

  • Kim, Hae Lim;Jeon, Yong-Ho;Park, Jae-Hyung;Yoon, Han-sam
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.28 no.4
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    • pp.469-476
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    • 2022
  • This study developed a Recurrent Neural Network model implemented through Long Short-Term Memory (LSTM) that generates long-term tidal level data at Busan Port using tide observation data. The tide levels in Busan Port were predicted by the Korea Hydrographic and Oceanographic Administration (KHOA) using the tide data observed at Busan New Port and Tongyeong as model input data. The model was trained for one month in January 2019, and subsequently, the accuracy was calculated for one year from February 2019 to January 2020. The constructed model showed the highest performance with a correlation coefficient of 0.997 and a root mean squared error of 2.69 cm when the tide time series of Busan New Port and Tongyeong were inputted together. The study's finding reveal that long-term tidal level data prediction of an arbitrary port is possible using the deep learning recurrent neural network model.

A Prediction System of SS Induced by Dredging (준설공사시 부유사 확산 예측시스템의 개발)

  • 정태성;김태식;강시환
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.16 no.1
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    • pp.47-55
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    • 2004
  • A SS prediction system using GUI in coastal region has been developed to predict the dispersion of the suspended sediments occurred by dredging. The prediction system uses a finite element hydrodynamic model to calculate water level and velocities and a random-walk particle tracking model to simulate SS dispersion. The system was applied to hindcast the tidal currents and SS concentrations in the Kunsan coastal waters. The simulated tidal currents showed good agreements with the observed currents. The transport model was verified for analytic solutions and field observation showing good agreements.