Journal of the Korean Society of Marine Environment & Safety (해양환경안전학회지)

The Korean Society of Marine Environment and safety (해양환경안전학회)
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Changes of Sedimentary Environment in the Tidal Flat of the Dammed Yeongsan River Estuary, Southwestern Coast of Korea

영산강 하구 갯벌의 퇴적환경 변화

  • Kim, Young-Gil (GeoSystem Research Corp.) ;
  • Lee, Myong Sun (Department of Marine Fisheries Resources, Mokpo National University) ;
  • Chang, Jin Ho (Department of Marine Fisheries Resources, Mokpo National University)
  • 김영길 ((주)지오시스템리서치) ;
  • 이명선 (목포대학교 해양수산자원학과) ;
  • 장진호 (목포대학교 해양수산자원학과)
  • Received : 2019.08.14
  • Accepted : 2019.10.28
  • Published : 2019.10.31
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Abstract

By monitoring sediment grain size and level variation of tidal flat surface for 6 years (2005-2011), and also by mooring TISDOS (tidal-flat sediment dynamics observation system) on the low intertidal flat in 2008, we investigated the sedimentary environment of tidal flat in the dammed Yeongsan River Estuary. The tidal flat of the Yeongsan River Estuary lost 82 % of its area because of coastal development projects, and a narrow tidal flat below mean sea level now remains. Most of the tidal flat sediments are composed of silt up to 70-94 %, and show the characteristics of clay deficiency and silt dominance. This is closely related with the coastal development, which led to the destruction of high tidal flats where most mud settled, and the modification of tidal current patterns. Moreover, the estuarine tidal-flat sediments reveal seasonal variation. They are coarse with abundant silt during windy autumn to spring, fine with abundant clay during the less-windy and high-discharge summer. This phenomenon indicates that the behavior of sediment particles on the low intertidal flats of the Yeongsan River Estuary is influenced by wind waves for silt and fresh water discharge and the tidal process for clay. Monitoring results of the altitude of tidal flat surface showed that the study area had eroded at an average rate of -2.6 cm/y during the period of 2005-2011, and also that an unusual deposition with a rate of 4 cm/y occurred in 2010. The erosion can be explained by an increased tidal amplitude and a strengthened ebb-dominant tidal asymmetry after the construction of an estuary dike and the Yeongam Kumho Seawall. The deposition in 2010 seems to have been closely related to the mass production of suspended materials from dredging of the estuary.

하굿둑과 좁고 깊은 수로형 하구의 특성을 갖는 영산강 하구에서 하구 갯벌의 퇴적환경 특성을 규명하기 위해 6년 동안(2005~2011) 표층퇴적물의 입도와 조간대 바닥의 높이 변화(침·퇴적 변화)를 모니터링 하였고, 2008년 9월에는 하구 조간대에서 수리관측을 수행하였다. 전체 갯벌의 82 %가 연안개발에 의해 사라진 영산강 하구의 갯벌은 현재 대부분 하부조간대의 좁은 갯벌로 남아있으며, 대부분 점토와 실트로 구성된 퇴적물은 전체의 70 ~ 94 %를 실트가 차지할 정도로 점토-부족, 실트-우세의 특성을 보인다. 이는 개발에 따른 점토퇴적 공간(즉 조상대와 상부 조간대)의 상실과 낙조류 우세의 조류 특성 변화에 기인된 것으로 판단된다. 또한 하구의 갯벌 퇴적물은 바람이 강한 가을부터 봄까지 실트가 많아져 조립해지고, 바람이 약하고, 방류량이 많은 여름에 점토가 많아져 상대적으로 세립해지는 계절적 변화를 보임으로써 하구 갯벌에서 퇴적물 입자의 거동이 실트 입자의 경우 풍파에 의해서, 점토 입자의 경우 주로 담수 방류와 조석작용에 의해 영향 받고 있음을 보여준다. 하구 갯벌에 대한 6년 동안(2005~2011)의 침·퇴적 모니터링 결과는 영산강 하구 조간대에서 연평균 -2.6 cm/y의 침식이 이루어졌고, 2010년경에는 특이하게 연평균 4 cm/yr의 퇴적이 일어났음을 보여준다. 이러한 하구 조간대의 침식은 하굿둑 및 영암-금호 방조제 건설 이후에 이루어진 조석의 진폭 증가와 낙조 우세 조류의 비대칭성 강화에 기인된 것으로 평가되며, 2010년의 퇴적은 하구 준설에 따른 부유물의 대량 발생과 관련이 있는 것으로 판단된다.

Keywords

References

  1. Alexander, C. R., C. A. Nittrour, D. J. Demester, Y. A. Park, and S. C. Park(1991), Macrotidal mudflats of the southwestern Korea coast: a model for interpretation of intertidal deposits, Journal of Sedimentary Petrology, Vol. 61, pp. 805-824.
  2. Bang, K. Y., T. I. Kim, Y. S. Song, J. H. Lee, S. W. Kim, J. G. Cho, J. W. Kim, S. B. Woo, and J. K. Oh(2013), Numerical Modeling of Sediment Transport during the 2011 Summer Flood in the Youngsan River Estury, Korea, Journal of Korean Society of Coastal and Ocean Engineers, Vol. 25, No. 2, pp. 76-93. https://doi.org/10.9765/KSCOE.2013.25.2.76
  3. Chang, J. H.(1995), Depositional processes in the Gomso bay tidal flat, West Coast of Korea, Seoul National University, Seoul, Korea, pp. 1-192.
  4. Chang, J. H., Y. S. Kim, and Y. G. Cho(1999), Tidal-Flat Sedimentation in a Semienclosed Bay with Erosional Shorelines: Hampyong Bay, West Coast of Korea, Journal of Korean Society of Oceanography, Vol. 4, No. 2, pp. 117-126.
  5. Chang, J. H. and J. Y. Choi(1998), Seasonal accumulation pattern and preservation potential of tidal-flat sediments: Gomso Bay, West Coast of Korea. Journal of Korean Society of Oceanography, Vol. 3, No. 3, pp. 149-157.
  6. Chun, S. S., H. J. Lee, S. O. Ryu, and B. C. Yang(1998), Seasonal and local variation of sedimentation on the wave-dominated tidal flats, southwestern coast of Korea; Comparison between inner-bay and open tidal flats, 15th International Sedimentological Congress, Alicante, Spain, Abstract, pp. 1-257.
  7. Chu, Y. S., H. J. Lee, E. S. Park, Y. G. Lee, and K. S. Jeong(2000), Summer-time behaviour and flux of suspended sediments at the entrance to semi-closed Hampyung bay, southwestern coast of Korea, Journal of the Korean Society of Oceanography, Vol. 5, No. 2, pp. 105-118.
  8. Folk, R. L.(1968), Petrology of Sedimentary Rocks, Hemphill's, Austin, USA, pp. 1-170.
  9. Folk, R. L. and W. C. Ward(1957), Brazos river bar: a study in the significance of grain size parameter, Journal of Sedimentary Petrology, Vol. 27, pp. 3-26. https://doi.org/10.1306/74D70646-2B21-11D7-8648000102C1865D
  10. Frey, R. W., J. D. Howard, S. J. Han, and B. K. Park(1989), Sediments and sedimentary sequenecs on a modern macrotidal flat, Incheon, Korea, Journal of Sedimentary Petrology, Vol. 59, pp. 28-44.
  11. Hong, S. J., D. I. Lee, D. M. Kim, and C. K. Park(2000), Material budgets in the Nakdong River Estuary with simple box model, Journal of the Korean Society for Marine Environmental Engineering, Vol. 3, No. 3, pp. 50-57.
  12. Jung, T. S. and J. H. Choi(2010), Numerical modeling of ebb-dominant tidal flow in the Mokpo coastal zone. Journal of the Korean Society of Coastal and Ocean Engineers, Vol. 22, No. 5, pp. 333-343.
  13. Jung, T. S.(2016), Inter-annual variation of tides on the western coasts of Korea, Journal of Korea Society of Coastal and Ocean Engineers, Vol. 28, No. 2, pp. 81-91. https://doi.org/10.9765/KSCOE.2016.28.2.81
  14. Kang, J. W.(1999), Changes in tidal characteristics as a result of the construction of sea-dike/sea-walls in the Mokpo coastal zone in Korea, Estuarine, Coastal and Shelf Science, Vol. 48, No. 4, pp. 429-438. https://doi.org/10.1006/ecss.1998.0464
  15. Kim, Y. H., H. J. Lee, S. K. Chough, S. C. Hun, and S. J. Han(1999), Holocene transgressive stratigraphy of macrotidal flat in the southeastern Yellow Sea: Gomso Bay, Korea, Journal of Sedimentary Research, Vol. 69, pp. 328-337. https://doi.org/10.2110/jsr.69.328
  16. Kim, J. G., D. M. Kim, and J. S. Yang(2000), Estimation of material budget for Keum river estuary using a box model. Journal of the Korean Society for Marine Environmental Engineering, Vol. 3, No. 4, pp. 76-90.
  17. Kim, Y. G. and J. H. Chang(2017). Long-term changes of bathymetry and surface sediments in the dammed Yeongsan-River Estuary, Korea, and their depositional implication. Journal of Korean Society of Oceanography, Vol. 22, No. 3, pp. 88-102.
  18. KMA(2012), Korea Meteorological Administration, Annual Climatological Report (2005-2011).
  19. KHOA(2016), Korea Hydrographic and Oceanographic Agency, Technical Report, pp. 1-221.
  20. KRCC(2016), Korea Rural Community Corporation, Notification of result of post-environmental impact survey of Yeongsan-River Estuary improvement project, Vol. 1-6.
  21. Lee, H. J., K. S. Bahk, H. R. Cho, Y. S. Chu, S. O. Sun, D. H. Kim, E. S. Park, C. K. Han, M. G. Kim, and K. H. Jeong(2002), Modeling of Sedimentary Dynamical Behavior of Coastal Suspended Sediments. Report (2000-N-NL-01-C-264), Korea Ocean Research and Development Institute, Ansan, Korea, p. 323.
  22. Lee, S. W.(1994), Korea Port Hydraulics Records, Jipmoondang, Seoul, Korea, pp. 93-116.
  23. Lee, K. S. and S. K. Jun(2009), Material budgets in the Youngsan river estuary with simple box model, Journal of the Korean Society for Marine Environmental Engineering, Vol. 12, No. 4, pp. 248-254.
  24. Lee, H. J., Y. S. Chu, and Y. A. Park(1999), Sedimentary processes of fine-grained material and the effect of seawall construction in the Daeho macrotidal flat nearshore area, northern west coast of Korea, Marine Geology, Vol. 157, pp. 171-184. https://doi.org/10.1016/S0025-3227(98)00159-5
  25. Lee, H. J., H. R., Jo, Y. S. Chu, and K. S. Bahk(2004), Sediment transport on macrotidal flats in Garolim Bay, west coast of Korea: significance of wind waves and asymmetry of tidal current, Continental Shelf Research, Vol. 24, pp. 821-832. https://doi.org/10.1016/j.csr.2004.01.005
  26. Postma, H.(1961), Transport and accumulation of suspended matters in the Dutch Wadden Sea, Nertherland Journal of Sea Research, Vol. 1, pp. 148-190. https://doi.org/10.1016/0077-7579(61)90004-7
  27. Ryu, S. O., H. S. You, and J. D. Lee(1999), Seasonal variation of surface sediments and accumulation rate on the intertidal flat in Hampyong Bay, southwstern coast of Korea, Journal of the Korean Society of Oceanography, Vol. 4, No. 2, pp. 127-135.
  28. Ryu, S. O., J. Y. Kim, and J. H. Chang(2001), Distribution of Surface Sediments and Sedimentation Rates on the Tidal Flat of Muan Bay, Southwestern Coast, Korea, Journal of The Korean Earth Science Society, Vol. 22, No. 1, pp. 30-39.
  29. Ryu, S. O.(2003), Seasonal Variation of Sedimentary Processes in a Seim-enclosed bay: Hampyong Bay, Korea, Estuarine, Coastal and Shelf Science, Vol. 56, pp. 481-492. https://doi.org/10.1016/S0272-7714(02)00199-3
  30. Van Straaten, L. M. J. U. and Ph. H. Kuenen(1957), Accumulation of fine grained sediments in the Dutch Wadden Sea, Geol. Mijnb. Vol. 19, pp. 329-354.
  31. Wells, J. T., C. E. Jr Adams, Y. A. Park, and E. W. Frankenberg(1990), Morphology, sedimentology and tidal channel processes on a high-tide-range mudflat, west coast of South Korea, Marine Geology, Vol. 95, pp. 111-130. https://doi.org/10.1016/0025-3227(90)90044-K