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Effect of Freshwater Discharge from a Water Reservoir on the Flow Circulation in the Semi-Closed Harbor

유수지로부터의 담수 방류가 항 내 해수순환에 미치는 영향

  • Choi, Jae Yoon (Department of Ocean Sciences, College of Natural Science, Inha University) ;
  • Kim, Jong Wook (Department of Ocean Sciences, College of Natural Science, Inha University) ;
  • Lee, Hye Min (Department of Ocean Sciences, College of Natural Science, Inha University) ;
  • Yoon, Byung Il (Department of Ocean Sciences, College of Natural Science, Inha University) ;
  • Woo, Seung-Buhm (Department of Ocean Sciences, College of Natural Science, Inha University)
  • Received : 2020.11.20
  • Accepted : 2020.12.17
  • Published : 2021.02.27

Abstract

To investigate the effect of freshwater discharge on the seawater circulation in the semi-closed harbor, a 3-D hydrodynamic model was applied to the International Ferry Terminal (IFT). The model run is conducted for 45 days (from May 15 to June 30, 2020), and the reproducibility of the model for time-spatial variability of current velocity and salinity was verified by comparison with model results and observation data. There are two sources of freshwater towards inside of the IFT: Han River and water reservoir located in the eastern part of IFT. In residual current velocity results, the two-layer circulation (the seaward flow near surface and the landward flow near bottom)derived from the horizontal salinity gradient in only considering the discharge from a Han River is more developed than that considering both the Han River and water reservoir. This suggests that the impact of freshwater from the reservoir is greater in the IFT areas than that from a Han River. Additionally, the two-layer circulation is stronger in the IFT located in southern part than Incheon South Port located in northern part. This process is formed by the interaction between tidal current propagating into the port and freshwater discharge from a water reservoir, and flow with a low salinity (near 0 psu) is delivered into the IFT. This low salinity distribution reinforces the horizontal stratification in front of the IFT, and maintains a two-layer circulation. Therefore, local sources of freshwater input are considered to estimate for mass transport process associated with the seawater circulation within the harbor and It is necessary to perform a numerical model according to the real-time freshwater flow rate discharged.

담수 유입이 항만 내 해수순환에 미치는 영향을 조사하기 위하여, 인천 남항의 남측에 위치한 신국제 여객터미널 해역에 3차원 유동 수치 모델을 구축 및 적용하였다. 수치 모델의 모의 기간은 경기만 지역의 평수기인 5월 15일부터 6월 30일까지 약 45일이며, 모델 결과와 관측자료의 비교를 통하여 유동과 염분 변화에 관한 모델의 재현성을 검증하였다. 신국제 여객터미널에 영향을 미치는 담수 공급원은 한강과 항만 동쪽에 위치한 용현 갯골 유수지가 있다. 유수지의 유무에 따른 잔차류 결과를 분석해 보면, 한강과 유수지가 모두 고려된 실험안이 한강만을 고려한 실험안보다 염분 경사에 의한 2층 흐름 구조(표층은 외해 방향, 저층은 항 내를 향한 흐름 구조)가 수평적으로 더 강하게 발달한다. 이는, 한강으로부터의 담수 영향보다 유수지로부터의 담수 영향이 신국제 여객터미널 해역에서 더 크다는 것을 시사한다. 또한, 잔차류의 2층 흐름 구조는 북쪽에 위치한 인천 남항보다, 남쪽에 위치한 신국제 여객터미널에서 더 강한 2층 흐름 구조가 발생한다. 이 프로세스는 유수지로부터의 담수와 항 내로 전파된 조류가 만나 신국제 여객터미널 방향으로 회전되어 전파되면서, 남쪽에 위치한 신국제 여객터미널에 저염수가 전달됨에 따라 형성된다. 이러한 흐름은 신국제 여객터미널 전면부에서 수평적인 염분 경사에 의한 성층을 강화시키며, 강화된 성층은 2층 흐름 구조를 형성 및 유지시킨다. 따라서, 항만 내의 경압 작용에 의한 해수순환과 물질이동을 재현하고자 할 때, 유수지와 같은 국지적인 담수 유입원이라도, 항만 내의 해수순환에 지배적인 영향을 미치므로, 현장 관측 자료를 기반으로 유수지에서 방류되는 실시간 담수 유량에 따른 수치모델을 수행해야 한다.

Keywords

Acknowledgement

이 논문은 2020년도 정부(과학기술정보통신부)의 재원으로 정보통신기획평가원의 지원을 받아 수행된 연구임(2020-0-01389, 인공지능융합연구센터지원(인하대학교)). 이 논문은 2021년 해양수산부 재원으로 해양수산과학기술진흥원의 지원을 받아 시행된 연구임(해양수치모델링과 지능정보기술을 활용한 해양예측 정확도 향상 연구).

References

  1. Baek, S.-H. (2010). A study on silt transport of seabed around Incheon Harbor. Journal of Korean Society of Coastal and Ocean Engineers, 22(3), 133-142 (in Korean).
  2. Burchard, H. (2002). Applied turbulence modelling in marine waters (Vol. 100). Springer Science & Business Media.
  3. Chen, C., Liu, H. and Beardsley, R.C. (2003). An unstructured grid, finite-volume, three-dimensional, primitive equations ocean model: application to coastal ocean and estuaries. Journal Atmospheric and Oceanic Technology, 20(1), 159-186. https://doi.org/10.1175/1520-0426(2003)020<0159:AUGFVT>2.0.CO;2
  4. Chen, C., Zhu, J., Zheng, L., Ralph, E. and Budd, J.W. (2004). A non-orthogonal primitive equation coastal ocean circulation model: application to Lake Superior. Journal of Great Lakes Research, 30, 41-54. https://doi.org/10.1016/S0380-1330(04)70376-7
  5. Chen, C., Beardsley, R.C. and Cowles, G. (2006a). An unstructured grid, finite-volume coastal ocean model (FVCOM) system. Advance in Computational Oceanography, 19(1), 78-89.
  6. Chen, C., Beardsley, R.C. and Cowles, G. (2006b). An unstructured grid, finite-volume coastal ocean model-FVCOM user manual, second edition, Tech. Rep. SMAST/UMASSD-06-0602, 318pp., Sch. for Mar. Sci. and Technol., Univ. of Mass-Dartmouth, New Bedford.
  7. Chen, C., Huang, H., Beardsley, R.C., Liu, H., Xu, Q. and Cowles, G. (2007). A finite-volume numerical approach for coastal ocean circulation studies: Comparisons with finite difference models. Journal of Geophysical Research, 112(C3).
  8. Cowles, G.W. (2008). Parallelization of the FVCOM coastal ocean model. The International Journal of High-Performance Computing Applications, 22(2), 177-193. https://doi.org/10.1177/1094342007083804
  9. Ge, J., Chen, C., Qi, J., Ding, P. and Beardsley, R.C. (2012). A dike-groyne algorithm in a terrain-following coordinate ocean model (FVCOM): Development, validation and application. Ocean Modelling, 47, 26-40. https://doi.org/10.1016/j.ocemod.2012.01.006
  10. Haidvogel, D.B., Arango, H., Budgell, W.P., Cornuelle, B.D., Curchitser, E., Di Lorenzo, E. and Levin, J. (2008). Ocean forecasting in terrain-following coordinates: Formulation and skill assessment of the Regional Ocean Modeling System. Journal of Computational Physics, 227(7), 3595-3624. https://doi.org/10.1016/j.jcp.2007.06.016
  11. Kang, Y.S., Chae, Y.K. and Lee, H.R. (2011). Variation of density stratification due to freshwater discharge in the Kwangyang Bay and Jinju Bay. Journal of Korean Society of Coastal and Ocean Engineers, 23(1), 126-137 (in Korean). https://doi.org/10.9765/KSCOE.2011.23.1.126
  12. Kim, C.K. and Park, K. (2012). A modeling study of water and salt exchange for a micro-tidal, stratified northern Gulf of Mexico estuary. Journal of Marine Systems, 96, 103-115. https://doi.org/10.1016/j.jmarsys.2012.02.008
  13. Kim, J.W., Yoon, B.I., Song, J.I., Lim, C.W. and Woo, S.B. (2013). Spatial and temporal variability of residual current and salinity according to freshwater discharge in Yeoungsan River estuary. Journal of Korean Society of Coastal and Ocean Engineers, 25(2), 103-111 (In Korea). https://doi.org/10.9765/KSCOE.2013.25.2.103
  14. Lee, G.H., Shin, H.J., Kim, Y.T., Dellapenna, T.M., Kim, K.J., Williams, J. and Figueroa, S.M. (2019). Field investigation of siltation at a tidal harbor: North Port of Incheon, Korea. Ocean Dynamics, 69(9), 1101-1120. https://doi.org/10.1007/s10236-019-01292-0
  15. Lerczak, J.A. and Rockwell Geyer, W. (2004). Modeling the lateral circulation in straight, stratified estuaries. Journal of Physical Oceanography, 34(6), 1410-1428. https://doi.org/10.1175/1520-0485(2004)034<1410:MTLCIS>2.0.CO;2
  16. Mellor, G.L. and Yamada, T. (1982). Development of a turbulence closure model for geophysical fluid problems. Reviews of Geophysics, 20(4), 851-875. https://doi.org/10.1029/RG020i004p00851
  17. Park, K., Oh, J.H., Kim, H.S. and Im, H.H. (2002). Case study: mass transport mechanism in Kyunggi bay around Han river mouth, Korea. Journal of Hydraulic Engineering, 128(3), 257-256. https://doi.org/10.1061/(asce)0733-9429(2002)128:3(257)
  18. Pietrzak, J., Jakobson, J.B., Burchard, H., Vested, H.J. and Petersen, O. (2002). A three-dimensional hydrostatic model for coastal and ocean modelling using a generalized topography following co-ordinate system. Ocean Modelling, 4(2), 173-205. https://doi.org/10.1016/S1463-5003(01)00016-6
  19. Ralston, D.K., Geyer, W.R., Traykovski, P.A. and Nidzieko, N.J. (2013). Effects of estuarine and fluvial processes on sediment transport over deltaic tidal flats. Continental Shelf Research, 60, S40-S57. https://doi.org/10.1016/j.csr.2012.02.004
  20. Smagorinsky, J. (1963). General circulation experiments with the primitive equations: I. The basic experiment. Monthly Weather Review, 91(3), 99-164. https://doi.org/10.1175/1520-0493(1963)091<0099:GCEWTP>2.3.CO;2
  21. Warner, J.C., Sherwood, C.R., Arango, H.G. and Signell, R.P. (2005). Performance of four turbulence closure models implemented using a generic length scale method. Ocean Modelling, 8(1-2), 81-113. https://doi.org/10.1016/j.ocemod.2003.12.003
  22. Yoo, S.J., Cha, Y.D. and Yeo, G.T. (2017). An analysis on optimal port operation for new international passenger terminal using conjoint analysis: Focusing on Incheon Port. Journal of Navigation and Port Research, 41(1), 17-24 (In Korean). https://doi.org/10.5394/KINPR.2017.41.1.17
  23. Yoon, B.I. and Woo, S.B. (2011). Study on relationship between geographical convergence and bottom friction at the major waterways in han river estuary using the tidal wave propagation characteristics. Journal of Korean Society of Coastal and Ocean Engineers, 23(5), 383-392 (In Korean). https://doi.org/10.9765/KSCOE.2011.23.5.383