Korean Journal of Soil Science and Fertilizer (한국토양비료학회지)

Korean Society of Soil Science and Fertilizer (한국토양비료학회)
권호 표지

The Simulation of Pore Size Distribution from Unsaturated Hydraulic Conductivity Data Using the Hydraulic Functions

토양 수리학적 함수를 이용한 불포화 수리전도도로부터 공극크기분포의 모사

  • Yoon, Young-Man (Biogas Research Center, Hankyong National University) ;
  • Kim, Jeong-Gyu (College of Life Science and Biotechnology, Korea University) ;
  • Shin, Kook-Sik (College of Agriculture and Life Science, Hankyong National University)
  • 윤영만 (한경대학교 바이오가스연구센터) ;
  • 김정규 (고려대학교 생명과학대학) ;
  • 신국식 (한경대학교 농업생명과학대학)
  • Received : 2010.08.02
  • Accepted : 2010.08.18
  • Published : 2010.08.31
Download PDF
⟨ Previous Next ⟩

Abstract

Until now, the pore size distribution, PSD, of soil profile has been calculated from soil moisture characteristic data by water release method or mercury porosimetry using the capillary rise equation. But the current methods are often difficult to use and time consuming. Thus, in this work, theoretical framework for an easy and fast technique was suggested to estimate the PSD from unsaturated hydraulic conductivity data in an undisturbed field soil profile. In this study, unsaturated hydraulic conductivity data were collected and simulated by the variation of soil parameters in the given boundary conditions (Brooks and Corey soil parameters, ${\alpha}_{BC}=1-5L^{-1}$, b = 1 - 10; van Genuchten soil parameters, ${\alpha}_{VG}=0.001-1.0L^{-1}$, m = 0.1 - 0.9). Then, $K_s$ (1.0 cm $h^{-1})$ was used as the fixed input parameter for the simulation of each models. The PSDs were estimated from the collected K(h) data by model simulation. In the simulation of Brooks-Corey parameter, the saturated hydraulic conductivity, $K_s$, played a role of scaling factor for unsaturated hydraulic conductivity, K(h) Changes of parameter b explained the shape of PSD curve of soil intimately, and a ${\alpha}_{BC}$ affected on the sensitivity of PSD curve. In the case of van Genuchten model, $K_s$ and ${\alpha}_{VG}$ played the role of scaling factor for a vertical axis and a horizontal axis, respectively. Parameter m described the shape of PSD curve and K(h) systematically. This study suggests that the new theoretical technique can be applied to the in situ prediction of PSD in undisturbed field soil.

토양의 공극 크기별 분포는 토양중 수분의 함량과 수분퍼텐셜의 관계를 나타내는 토양수분특성 자료로부터 계산된다. 그러나 기존의 토양수분특성 측정방법들은 교란된 토양을 이용하거나 코어시료를 채취한다 하여도 동역학적으로 변화하는 현장 토양 공극분포를 반영하는 데는 많은 어려움이 있었다. 또한 이러한 토양수분특성 자료를 얻기 위해서는 많은 시간과 노력이 요구되어 왔다. 따라서 본 연구에서는 교란되지 않은 현장 토양에서 측정한 불포화 수리전도도 자료로부터 토양의 공극 크기별 분포 곡선을 추정하는 이론적 체계를 제시하고자 하였다. 이를 위해 Brooks-Corey와 van Genuchten의 수리학적 모델을 이용하여 토양의 불포화 수리전도도 자료로부터 공극의 크기별 분포를 추정하는 이론적 모델을 전개하였으며, 이러한 이론적 모델에 근거하여 Brooks-Corey와 van Genuchten의 soil parameter들의 변화에 따른 불포화수리전도도와 공극 크기별 분포곡선의 모사하였다. 공극크기별 분포곡선의 모사는 토성별 불포화수리전도도 곡선의 scaling factor 역할을 하는 $K_s$를 1.0 cm $h^{-1}$로 설정하고, 수리학적 모델별로 일정한 경계조건 (Brooks-Corey soil parameters, ${\alpha}_{BC}=1-5L^{-1}$, b = 1 - 10; van Genuchten soil parameters, ${\alpha}_{VG}=0.001-1.0L^{-1}$, m = 0.1 - 0.9)에서 수행하였다. Brooks-Corey 모델을 이용한 공극 크기별 분포곡선의 모사에서는 parameter b가 공극분포곡선의 형태에 영향을 주었으며, ${\alpha}_{BC}$는 공극분포곡선의 민감도에 영향을 주었다. 또 van Genuchten 모델을 이용한 공극 크기별 분포곡선의 모사에서는 ${\alpha}_{VG}$가 scaling factor의 역할을 하였으며, parameter m은 공극분포곡선의 형태에 영향을 주었다. 따라서 경계조건 안에서 불포화 수리전도도 자료로부터 공극의 크기별 분포 모사가 가능하였으며, 토양 parameter들이 토성, 입자분포 등의 물리적 특성을 잘 반영하는 경우 이론적으로 현장 토양의 공극 크기별 분포의 추정이 가능할 것으로 판단되었다.

Keywords

References

  1. Ahuja, L,R., D.K. Cassel, R.R. Brucc, and B.B. Barnes. 1989. Evaluation of spatial distribution of hydraulic conductivity using effective porosity data. J. Soil Sci. 148:404-411. https://doi.org/10.1097/00010694-198912000-00002
  2. Ankeny, M.D., M. Ahmed, T.C. Kaspar, and R. Horton. 1991. Simple field method for determining unsaturated hydraulic conductivity. Soil Sci. Soc. Am. J. 55:467-470. https://doi.org/10.2136/sssaj1991.03615995005500020028x
  3. Ankeny, M.D., T.C. Kaspar. and R. Horton. 1988. Design for an automated tension infiltrometer. Soil Sci. Soc. Am. J. 52:893-895. https://doi.org/10.2136/sssaj1988.03615995005200030054x
  4. Brooks. R.H. and A.T. Corey. 1964. Hydraulic properties of porous media. Hydrology paper no. 3. Civil Engineering Dep., Colorado State Univ., Fort Collins. CO. USA.
  5. Brooks. R.H. and A.T. Corey. 1966. Properties of porous media affecting fluid now. J. lrrig. Drain. Dic. Am. Soc. Civ. Eng. 92:61-88.
  6. Burdine, N.T. 1953. Relalive permeability calculalions from PDS data. Trans. AIME 198:71-77.
  7. Campbell. G.S. 1974. A simple method for determining unsaturated conductivity from moisture retention data. J. Soil Sci. 117: 311-314. https://doi.org/10.1097/00010694-197406000-00001
  8. Childs, E.C. 1969. An introduction to the physical basis of soil water phenomena. London: Willey. Interscience.
  9. Dumer. W. 1992. Predicting the unsaturated hydraulic conductivity using multi. porosity water retention curves. pp.185-202. In van Genuchten, M.Th. el al. (ed.) Indirect methods for estimating the hydraulic properties of unsaturated soils. Univ. of California, Riverside.
  10. Everts. C.J . and R.S Kanwar. 1993. Interpreting tension-infiltrometer data for quantifying soil macropores: Some panicle considerations. Trans. ASAE 36(2):423-428. https://doi.org/10.13031/2013.28354
  11. Logsdon, S.D., E.L. McCoy, R.R. Allmaras. and D.R. Linden. 1993. Macropore characterization by indirect methods. J. Soil Sci. 155: 316-324. https://doi.org/10.1097/00010694-199305000-00002
  12. Luckner, L., M.Th. van Genuchten. and D.R. Nielsen. 1989. A consistent set of parametric models for the two-phase flow of of immiscible fluids in the subsurface. Water Resour. Res. 25:2187-2193. https://doi.org/10.1029/WR025i010p02187
  13. Mualem, Y. 1976. A new model predicting the hydraulic conductivity of unsaturated porous media. Water Resour. Res. 12 :513-522. https://doi.org/10.1029/WR012i003p00513
  14. Nachabe. M.H. 1996. Macroscopic capillary length. sorpivity, and shape factor in modeling the infiltration rate. Soil Sci. Soc. Am. J. 60:957-962. https://doi.org/10.2136/sssaj1996.03615995006000040001x
  15. Othmer, H., B. Diekkruger, and M. Kutillek, 1991. Bimodal porosity and unsaturated hydraulic conductivity. J. Soil Sci. 152:139-150. https://doi.org/10.1097/00010694-199109000-00001
  16. Perroux, K.M. and I. White. 1988. Designs for disc permeameters. Soil Sci. Soc. Am. J. 52:1205-1215. https://doi.org/10.2136/sssaj1988.03615995005200050001x
  17. Rawls, W.J. and D.L Brakensiek. 1985. prediction of soil water properties for hydrologic modeling. p.293-299. In Jones, E.B. and T.J. Ward. (ed.) Watershed management in the eighties. Proc. Irrig. Drain div.,ASCE. Denver. CO. 30 April-1 May 1985. Am.Soc. Civil Eng ., New York, NY, USA.
  18. Reynolds, W.D. and D.E. Elrick. 1991. Determination of hydraulic conductivity using a tension infiltrometer. Soil Sci. Soc. Am. J. 55:633-639. https://doi.org/10.2136/sssaj1991.03615995005500030001x
  19. Ross, P.J. and K.R.J. Smettem. 1993. Describing soil hydraulic properties with sums of Simsof functions. Soil Sci. Soc. Am. J. 57:26-29. https://doi.org/10.2136/sssaj1993.03615995005700010006x
  20. Saxton. K.E., W.J. Rawls, J.S. Romberger. and R.I. Papendick. 1986. Estimation generalized soil-water characteristics from texture. Soil Sci. Soc. Am. J. 50:1031-1036. https://doi.org/10.2136/sssaj1986.03615995005000040039x
  21. Schaap, M.G. and F.J. Leij. 2000. Improved prediction of unsaturated hydraulic conductivity with the Mualem-van Grnuchten model. Soil.Sci. Soc. Am. J. 64:843-851. https://doi.org/10.2136/sssaj2000.643843x
  22. Smetten. K.R.J. and C. Kirkby. 1990. Measuring the hydraulic properties of a stable aggregated soil. J. Hydrol. 17: 1-13.
  23. Timlin, D.J.. L.R. Ahuja. and M.D. Ankeny. 1994. Comparison of three field methods to Characterize apparent macropore conductivity. Soil Sci. Soc. Am. J. 58:278-284. https://doi.org/10.2136/sssaj1994.03615995005800020003x
  24. van Genuchten, M.Th. 1980. A closed form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44:892-898. https://doi.org/10.2136/sssaj1980.03615995004400050002x
  25. van Genuchten, M.Th. and D.R. Nielsen. 1985. On describing and predicting the hydraulic properties of unsaturated soils. Ann. Geophysicae 3:615-628.
  26. Vogeler, I., B.E. Clothier. S. R. Green. D.R. Scotter, and R.W. Tillman. 1996. Characterizing water and Solute movement by lime domain re f1etlometry and disk permeametry. Soil Sci. Soc. Am. J. 60:5-12. https://doi.org/10.2136/sssaj1996.03615995006000010004x
  27. White. I. and K.M . Perroux. 1989. Estimation of unsaturated hydraulic conductivity from field sorptivity measurements. Soil Sci. Soc. Am. J. 53:324-329. https://doi.org/10.2136/sssaj1989.03615995005300020002x
  28. White, I. and M.J. Sully. 1987. Macroscopic and microscopic capillary Iength and time scales from field infiltration. Water Resour. Res. 23: 1514-1522. https://doi.org/10.1029/WR023i008p01514
  29. White. I.. M.J. Sully, and K.M. Perroux. 1992. Measurement of surface Soil hydraulic properties: Disk permeameters. tension infiltrometers. and other techniques. p.69-103. In Topp et al.(ed.) Advances in measurement of soil physical properties: Bringing theory into practice. SSSA Spec. Publ. 30. SSSA, Madison. WI.
  30. Wooding, R.A. 1968. Steady infiltration from a shallow circular pond. Water Resour. Res. 4:1259-1273. https://doi.org/10.1029/WR004i006p01259
  31. Yoon,Y., J.G. Kim, and S. Hyun. 2007. Estimating soil water retention in a selected range of soil pores using tension disc infiltrometer. Soil Till. Res. 97:107-116. https://doi.org/10.1016/j.still.2007.09.003