토양의세립분함량과염분농도가 TDR 측정값에미치는영향고찰

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1 한국관개배수제 13 권제 2 호 KCID J. VOL. 13, No.2 (26. 12) pp 논문 토양의세립분함량과염분농도가 TDR 측정값에미치는영향고찰 A Consideration on the Effect of the Fine Content and Salinity of Soils on the TDR Measurement 이행우 * 유찬 * 이근후 ** 박광수 **** Lee, Haeng Woo Yu, Chan Lee, Keun-Hoo Park, Kwang Soo Abstract Experimental laboratory tests were carried out to assess the effect of fine content and salinity of soils on the measurement of TDR(Time Domain Reflectometry). In the test, using soil column which was made by PVC pipe with the dimension of 25cm height and 2cm diameter, the salinity variation of soil was controlled by the solution which was dissolved NaCl to destilled water in the range of ~4g L -1. The fine content of soil was controlled by kaolinite which was mixed with Jumunjin sand in the range of ~5% to the total dry weight. The water contents of soil tested were measured with the conventional oven dry method beside TDR and compared the these values to figure out the extent of effect. As the results of tests, it was appeared that the water content measurement by TDR can be affected by the salinity level, fine contents, and the degree of saturation of the soil. Ⅰ. 서론 * 경상대학교지역환경기반공학과교수 ( 경상대농업생명과학연구원 ) (chanyu@gsnu.ac.kr) ** 경상대학교농업생명과학대학교수 (khlee@gsnu.ac.kr) 키워드 : TDR, 함수비, 토양염도, 세립분함량, 포화도

2 Fig. 1. Schematic diagram of soil water content measurement using TDR Ⅱ. 재료및실험 EFFECTIVE VOLTAGE REFLECTION OFF OF END OF WAVEGUIDE VOLTAGE LEVEL AT CONNECTOR CABLE VOLTAGE LEVEL OF DRY SOIL START OF WAVEGUIDES TRANSIT TIME IN WAVEGUIDES TIME IN NANOSECONDS Fig. 2. Reflection wave from TDR

3 Fig. 3. Soil column & Trase-1 TDR Fig. 4. TDR waveguide (3-wire buried type)

4 Ⅲ. 결과및고찰 (a) NaCl g L -1 (EC=.1 ds m -1 ) (b) NaCl 1g L -1 (EC=.98 ds m -1 ) (c) NaCl 2g L -1 (EC=1.894 ds m -1 ) (d) NaCl 4g L -1 (EC=3.54 ds m -1 ) Fig. 5. Relationship between water content and salinity of soils

5 (a) NaCl g L -1 (b) NaCl 1g L (c) NaCl 2g L -1 (d) NaCl 4g L Fig. 6. Influence of the fine content with the soil salinity variation on the TDR measurement [S: Sand content (%), F: Fine content (%)]

6 Table 1. Summary of the average error with test conditions NaCl (g L -1 ) Mixing ratio S1:F 4.23% 1.64% 7.99% 23.48% S9:F1 8.38% 9.55% 9.55% 14.97% S8:F2 7.65% 12.72% 5.12% 16.55% S7:F3 4.71% 9.75% 12.41% 25.23% S5:F5 6.94% 11.8% 15.34% 15.9% Average 6.38% 1.75% 1.9% 19.22%

7 Deviation S1:F S9:F1 S8:F2 S7:F3 S5:F5 Deviation S1:F S9:F1 S8:F2 S7:F3 S5:F Degree of saturation (%) Degree of saturation (%) (a) NaCl g L -1 (b) NaCl 1g L -1 Deviation S1:F S9:F1 S8:F2 S7:F3 S5:F5 Deviation S1:F S9:F1 S8:F2 S7:F3 S5:F Degree of saturation (%) Degree of saturation (%) (c) NaCl 2g L -1 (d) NaCl 4g L -1 Fig. 7. Comparision of the effect of the fine content and salinity on the TDR measurement with the degree of saturation of soil

8 Ⅳ. 결론 1. 박재현, 1998, 비포화영역에서용존오염물질거동에관한실험적연구, 서울대학교박사학위논문, p Dalton, F. N., 1992, Development of time-domain reflectometry for measuring soil water content and bulk density. In Topp, G. C. et al., Eds. Advances in measurement of soil physical properties: bringing theory into practice. Sepc. Publ. No. 3, SSSA, pp Hamed, Y., M. Persson, & R. berndtsson, 25, Using Time Domain Reflectometry for Tracking Water and Salinity Movements in a Contour Ridge Managed Catchment in Tunisia, pp.1, from M. Persson's internet site. 4. Herkelrath, W. N., 1991, Automatic, real time monitoring of soil moisture in a remote field area with TDR, Water resource research, 27, pp Persson M., 21, Using Time Domain Reflectometry for Non-Aqueous Phase Liquid Saturation Measurements, TDR-21, 2nd Intl' symposium & workshop on T.D.R. innovative geotechnical application, IL, USA, pp Roberto, A., 22, A simple emperical method to evaluate the electrical conductivity of soils and waters by TDR, 17th WCSS, pp Soilmoisture Equipment Corp., 1996, Operating instruction, version Topp, G.C., J.L. Davis, and A.P. Annan Electromagnetic determination of soil water content: Measurements in coaxial transmission lines. Water Resour. Res. 16, pp White, I. & S.J. Zegelin, 1995, Electric and dielectric methods for monitoring soil-water content, Handbook of vadose zone characterization & monitoring(wilson, Everett & Cullen ed.), pp , Lewis. 1. Zegelin, S. J., White, I. & Russell, G. F., 1992, A critique of the time domain reflectometry technique for determining field soil water content, In Topp, G. C. et al., Eds. Advances in measurement of soil physical properties: bringing theory into practice. Sepc. Publ. No. 3, SSSA, pp 본연구는환경부 핵심환경기술개발연구사업 의지원 ( 과제번호 2682) 에의해수행된연구결과임.