한국수자원학회논문집 (Journal of Korea Water Resources Association)

  • 제30권6호
  • /
  • Pages.587-595
  • /
  • 1997
  • /
  • 2799-8746(pISSN)
  • /
  • 2799-8754(eISSN)
한국수자원학회 (Korea Water Resources Association)
권호 표지

TDR(Time Domain Reflectometry)을 이용한 토양함수량의 측정

Measurement of Soil Water Content by Time Domain Reflectometry

  • 박재현 (서울대학교 토목공학과) ;
  • 윤성용 (안산공업전문대학 토목공학과) ;
  • 김상준 (경원대학교 토목공학과, 서울대학교)
  • Park, Jae-Hyeon (Dept. of Civil Engineering, Engineering College, Seoul National University) ;
  • Yun, Seong-Yong (Department of Civil Eng., Ansan College of Technology) ;
  • Kim, Sang-Jun (Department of Civil Eng., Kyung Won University, Seoul University)
  • 발행 : 1997.12.01
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

비포화 흐름에 관하 실험은 토양내 물의 이송특성을 밝히는 매우 중요한 의미를 가지고 있다. 하지만 Tensiometer와 같은 전통적인 측정방법은 비교적 길기 때문에 함수량이 급격하게 변하는 비정상류 비포화흐름을 측정하는데 상당한 어려움이 따른다. 본 연구에서는 TDR을 이용하여 이러한 문제를 해결할 수 있는 함수량 측정방법을 소개하고자 한다. TDR은 구형파를 발생시키는 함수방생기와 반향파를 분석하는 오실로스코프로 구성되어 있다. 토양속에 설치된 탐침을 지나는 구형파는 임피던수가 변하는 지점에서 반향되며 주변토양의 우전율상수 변화에 따라 전파속도가 달라지게 된다. 이 때 토양내 함수량은 함수량에 따른 반향시간특성을 이용하여 추정되어진다. TDR을 이용하는 함수량측정의 검증실험에 의하면 오븐 건조한 함수량에 대한 TDR측정 함수량의 오차율이 3.5% 이내 이었다. 따라서 TDR은 국내토양에 대한 비정상류 상태의 비포화흐름을 측정하는데 매우 훌륭한 실험장치로 판단된다.

Experimental study on unsaturated flow in the soil is important to understand the characteristics of the water flow. Measurement of unsteady-state water movement using the traditional equipment (e.g. tensiometer) has a problem that requires relatively a long response time. In this study a quick measurement method of soil water flow using TDR is introduced. TDR consists of an electronic function generator which generates a squared wave, and an oscilloscope which catches the reflected wave. The wave is reflected where both the impedance of the transmission line and the propagation velocity are changed. The water content can be obtained from the travel time measured by means of TDR because the dielectric constant is affected by the change of soil water content. From the result of TDR calibration. TDR measurement error for the oven dried soil was found to be less than 3.5%. This supports that TDR is a viable technique to measure the unsteady-state water movement.

키워드

참고문헌

  1. Soil Sci. Soc. Am. J. v.54 System for automating and multiflexing soil moisture measurement by TDR Baker, J. M.;Allmaras, R. R.
  2. Soil Science v.147 The spatial sensitivity of TDR Baker, J. M.;Lascano, R. J.
  3. Advances in measurement of soil physical properties : bringing theory into practice Development of time-domain reflectometry for mesuring soil water content and bulk soil electrical conductivity Dalton, F. N.;Topp. G. C.(ed.)(et al.)
  4. J. Phys. Chem. v.73 The measurement of dielectrics in time domain Fellner-Feldegg, H.
  5. Methods of Soil Analysis. Water content Gardner, W.H.
  6. Water Resour. Res. v.26 A computer-controlled 36 channel TDR system for monitoring soil water contents Heimovaara, T. J.;Bouten, W.
  7. Water Resour. Res. v.27 Automatic, real time monitoring of soil moisture in a remote field area with TDR Herkelrath, W. N.;Mamburg, S. P.;Murphy, F.
  8. Soil Sci. Soc. Am. J. v.59 Using short soil moisture probes with high bandwidth Time Domain Reflectometry instruments Kelly, S. F.;Selker, J. S.;Green, J. L.
  9. Econ. Environ. Geol. v.29 no.6 Application of an automated time domain reflectometry to solute transport study at field scale : Experimental mehtodology and calibration of TDR Kim, D. J.
  10. Econ. Environ. Geol. v.29 no.6 Application of an automated time domain reflectometry to solute transport study at field scale : Transport concept Kim, D.J.
  11. Soil Sci. Soc. Am. J. v.57 Simple Baluns in parallel probes for time domain reflectory Spaans, E. J. A.;Baker, J. H.
  12. Soil sampling & methods of analysis Soil water content Topp, G. C.;Carter, M. R.(ed.)
  13. Advances in irrigation v.3 Time domain reflectometry(TDR) and its application to irrigation scheduling Topp, G. C.;Davis, J. L.;Hillel, D.(ed.)
  14. Water Resour. Res. v.16 Electromagnetic determination of soil water content : mesurements in coaxial transmission lines Topp. G. C.;Davis, J. L.;Annan, A. P.
  15. Water Resour. Res. v.25 Improved fielld probes for soil water content and electrical conductivity measurement using time domain reflectometry Zegelin, S. J.;White, I.;Jenkins, D. R.
  16. Advances in measurement of soil physical properties: bringing theory into practice no.30 A critique of the time domain reflectometry technique for determing field soil water content Zegelin, S.J.;White, I.;Russell, G.F.;Topp, G.C.(et al.)