Journal of Korea Water Resources Association (한국수자원학회논문집)

Korea Water Resources Association (한국수자원학회)
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Composite model for seawater intrusion in groundwater and soil salinization due to sea level rise

해수면 상승으로 인한 지하수 해수침투 및 토양 염류화 합성 평가모델

  • Received : 2017.04.03
  • Accepted : 2017.05.08
  • Published : 2017.06.30
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Abstract

Sea level rise, accompanied by climate change, is expected to exacerbate seawater intrusion in the coastal groundwater system. As the salinity of saturated groundwater increases, salinity can increase even in the unsaturated soil above the groundwater surface, which may cause crop damage in the agricultural land. The other adverse impact of sea level rise is reduced unsaturated soil thicknesses. In this study, a composite model to assess impacts of sea level rise in coastal agricultural land is proposed. The composite model is based on the combined applications of a three dimensional model for simulating saltwater intrusion into the groundwater and a vertical one dimensional model for simulating unsaturated zone flow and transport. The water level and salinity distribution of groundwater are calculated using the three dimensional seawater intrusion model. At some uppermost nodes, where salinity are higher than the reference value, of the 3D mesh one dimensional unsaturated zone modeling is conducted along the soil layer between the ground water surface and the ground surface. A particular location is judged salinized when the concentration at the root-zone depth exceeds the tolerable salinity for ordinary crops. The developed model is applied to a hypothetical agricultural reclamation land. IPCC RCP 4.5 and 8.5 scenarios were used as sea level rise data. Results are presented for 2050 and 2100. As a result of the study, it is predicted that by 2100 in the climate change scenario RCP 8.5, there will be 7.8% increase in groundwater saltwater-intruded area, 6.0% increase of salinized soil area, and 1.6% in increase in water-logging area.

기후변화에 따른 해수면 상승으로 인하여 해안지역의 지하수계에 해수침투가 가중된다. 지하수의 염분농도가 증가하면 지하수면 상부의 불포화 토양에서도 염분 농도가 증가할 수 있으며, 이는 농경지에서 작물피해를 일으킬 수 있다. 해수면이 상승함에 따라 내륙의 지하수위도 함께 상승한다. 이는 불포화 토양층의 두께를 감소시켜 해안 저지대의 경작에 피해를 끼칠 수 있다. 본 연구에서 지하수 해수침투는 3차원 모델, 토양 염류화 평가는 연직 1차원 모델을 합성 적용하여 해안 농경지에 대한 해수면 상승 피해를 평가하는 방법을 개발하였다. 3차원 해수침투 모델에서 지하수면의 수위와 농도분포를 계산하고 최상부 절점 중에서 염분 농도가 기준 값 이상인 절점에서 지하수면과 지표면 사이의 토양층에서 연직 1차원 모델링으로 토양층의 염분 농도와 불포화대 두께를 계산하였다. 농경지의 토양 염류화는 작물의 뿌리 심도에서 보통 작물의 생육한계 염분농도를 기준으로 판단하였다. 개발된 모델링 방법을 가상의 간척농경지에 적용하였다. 해수면 상승자료로 IPCC의 RCP 4.5와 8.5 시나리오를 사용하였다. 평가 결과는 2050년과 2100년에 대하여 제시하였다. 연구결과 대상지역에서 기후변화 시나리오 RCP 8.5에서 2100년에는 지하수 염류화 피해 면적은 간척지 육지면적 대비 7.8%, 염류화 토양 면적은 6.0%, 불포화층의 두께가 뿌리심도보다 적은 지역의 면적은 1.6% 증가하는 것으로 분석되었다.

Keywords

References

  1. Dehaan, R. L., and Taylor, G. R. (2002). "Field-derived spectra of salinized soils and vegetation as indicators of irrigation-induced soil salinization." Remote sensing of Environment, Vol. 80, No. 3, pp. 406-417. https://doi.org/10.1016/S0034-4257(01)00321-2
  2. Essink, G. H. P., Van Baaren, E. S., and De Louw, P. G. (2010). "Effects of climate change on coastal groundwater systems: a modeling study in the Netherlands." Water Resources Research, Vol. 46, No. 10.
  3. Ferguson, G., and Gleeson, T. (2012). "Vulnerability of coastal aquifers to groundwater use and climate change." Nature Climate Change, Vol. 2, No. 5, pp. 342-345. https://doi.org/10.1038/nclimate1413
  4. Huyakorn, P. S., and Buckley, J. E. (1987). VADOFT: finite element code for simulating one-dimensional flow and solute transport in the vadose-zone. Technical Report Prepared for the US Environmental Protection Agency, Athens, GA.
  5. IPCC (2007). Impacts, adaptation and vulnerability. contribution of working group II to the fourth assessment report of the intergovernmental panel on climate change. Cambridge University Press, Cambridge. UK.
  6. Kang, J. W., Moon, S. R., and Oh, N. S. (2005). "Sea level rise at the southwestern coast." Korean Society of Civil Engineers, Vol. 25, No. 2B, pp.151-157.
  7. Kim, S. G. (2014). "Development of reclaimed farm lands for future agriculture." Proceedings Symposium on Revitalization of Agriculture in Reclaimed Land, Grand Hall, aT Center, Korea Rural Community Corporation and Rural Development Administration, pp. 83-99.
  8. Kitamura, Y., Yano, T., Honna, T., Yamamoto, S., and Inosako, K. (2006). "Causes of farmland salinization and remedial measures in the Aral Sea basin - research on water management to prevent secondary salinization in rice-based cropping system in arid land." Agricultural Water Management, Vol. 85, No. 1, pp. 1-14. https://doi.org/10.1016/j.agwat.2006.03.007
  9. Korea Meteorological Administration (2012). Korea climate change report. No. 11-1360000-000861-01, Korea
  10. Korea Rural Community Corporation (1999). Studies on tidal land reclamation and creation of environmental amenity. Ministry of Agriculture, Food and Rural Affairs, pp. 27.
  11. Korea Rural Community Corporation (2015a). Seawater intrusion estimation report. KRCC Publication No. 11-1543000-001105-10, pp. 301-308.
  12. Korea Rural Community Corporation (2015b). Seawater intrusion estimation report. KRCC Publication No. 11-1543000-001105-10, pp. 269-275.
  13. Narayan, K. A., Schleeberger, C., and Bristow, K. L. (2007). "Modelling seawater intrusion in the Burdekin Delta irrigation area, North Queensland, Australia." Agricultural Water Management, Vol. 89, No.3, pp. 217-228. https://doi.org/10.1016/j.agwat.2007.01.008
  14. Oh, Y. J., Kim, M. H., Na, Y. E., Hong, S. H., Paik, W. K., and Yoon, S. T. (2012). "Vulnerability assessment of soil loss in farm area to climate change adaption." Korean Society of Soil Sciences and Fertilizer, Vol. 45, No. 5, pp. 711-716. https://doi.org/10.7745/KJSSF.2012.45.5.711
  15. Park, J. J. (2009). "Vulnerability and adaptation to sea level rise and storm surge." The Geographical Journal of Korea, Vol. 43, No. 3, pp. 435-454.
  16. Van Genuchten, M. Th. (1980). "A closed-form equation for predicting the hydraulic conductivity of unsaturated soils." Soil Science Society of America Journal, Vol. 44, No. 5, p. 892-898. https://doi.org/10.2136/sssaj1980.03615995004400050002x
  17. Vinsome, P. K. W. (1976). "Orthomin, an iterative method for solving sparse sets of simultaneous linear equations." SPE Symposium on Numerical Simulation of Reservoir Performance, Society of Petroleum Engineers.
  18. Voss, C. I. (1984). SUTRA (Saturated-Unsaturated Transport). A Finite-Element Simulation Model for Saturated-Unsaturated, Fluid-Density-Dependent Ground-Water Flow with Energy Transport or Chemically-Reactive Single-Species Solute Transport No. USGS/WRI/84-4369. Geological Survey Reston VA Water Resources DIV.
  19. Werner, A. D., and Si mmons, C. T. (2009). "Impact of sea-level rise on sea water intrusion in coastal aquifers." Ground Water, Vol. 47, No. 2, pp. 197-204. https://doi.org/10.1111/j.1745-6584.2008.00535.x