基于探地雷达的田块尺度下不同深度土壤含水量监测

doi:10.12133/j.smartag.SA202202010

摘要/Abstract

摘要：

为确定田块尺度下探地雷达对不同深度及相邻反射层间土壤含水量的反演精度、有效反演深度、最佳反演深度及最优反演模型，本研究采用1000 MHz中心频率探地雷达设备，分别在无降雨偏干旱土壤和降雨后湿润土壤两种条件下，在选定农田区域基于共中心点法采集雷达波数据，提取有效地表波与反射波数据，通过双曲线拟合法分别获取不同深度反射层雷达波的传播速度，计算得出土壤的相对介电常数，最后根据土壤体积含水量和介电常数之间的经验模型计算获得不同深度的土壤体积含水量。通过Topp、Roth、Herkelrath和Ferre四种经验模型分别进行土壤体积含水量反演测定，同时以利用烘干法获取的代表性测定土壤含水量实测值为指标进行精度验证。田间试验结果表明，1000 MHz探地雷达的有效反演深度范围为0~50 cm；土壤偏干旱和偏湿润条件的最佳反演深度分别为50 cm和40 cm；Roth模型相关性最好，决定系数R²最高为0.750，且Roth模型反演土壤含水量值最稳定，在土壤偏干旱和偏湿润条件下均方根误差（Root Mean Square Error，RMSE）平均值分别为0.0401 m³/m³和0.0335 m³/m³；相对误差（Relative Error，RE）最低为3.0%。探地雷达具备对定量深度田间土壤含水量快速、精准监测的能力，但其反演模型需根据不同土壤类型等条件进行相应参数校正。

关键词: 探地雷达, 土壤含水量监测, 共中心点法, 最佳反演深度, 最优反演模型, Roth模型

Abstract:

Ground-penetrating radar (GPR) is one of the emerging technologies for soil moisture measurement. However, the measurement accuracy is difficult to determine due to some influence factors including radar wave frequency, soil texture type, etc. The GPR equipment with 1000 MHz center frequency and the measurement method of common midpoint (CMP) were adopted in the research to collect radar wave raw data in the selected field area under arid soil and moist soil conditions. The transmitter and receiver antennas of the GPR equipment were moved 0.01 m respectively in opposite directions on each radar wave raw data collection. Therefore, a CMP radar image consisted of 100 pieces of radar wave raw data by increasing the antenna distance from 0 m to 2 m. Each radar wave raw data indicated that the radar waves were reflected in the reflective layer with different dielectric constant under the same antenna distance. And the reflected and refracted radar waves were acquired by the receiving antenna at different two-way travel time respectively, and recorded in the computer. The collection of CMP soundings aimed to determine the inversion accuracy, optimum inversion depth, effective inversion depth and optimal inversion model of soil moisture content at different depth ranges and adjacent reflective layers by GPR at field scale. The reflected and refracted radar wave data were extracted from the raw data. The velocities of the surface waves and reflected waves were obtained respectively from the line slope of the surface wave data and the hyperbolic curves fitting of the reflected wave data. In addition, the relative dielectric constant of the soil at specified depth were deduced according to the soil dielectric constant and its reflected wave velocity. Moreover, 4 different models including Topp, Roth, Herkelrath and Ferre were used to figure out the soil volumetric water content inversion. Meanwhile, the measured data of soil volumetric moisture content obtained by oven drying method were used to verify the accuracy of the inversion results. The results showed that the effective inversion depth of 1000 MHz GPR ranged from 0 to 50 cm. The best inversion depth was 50 cm in arid soil and 40 cm in moist soil. The Roth model had the best correlation and stability with the highest R² was 0.750, the Root Mean Square Error (RMSE) was 0.0114 m³/m³ and the lowest Relative Error (RE) was 3.0%. The GPR could possess the capacity of quick, precise and non-destructive measurement of specified depth soil moisture in field scale. The inversion model of soil moisture content needs to be calibrated according to different soil conditions.

Key words: ground penetrating radar, soil water content monitoring, common midpoint, optimum inversion depth, optimum inversion model, Roth model

中图分类号:

P412.25

张文瀚, 杜克明, 孙彦坤, 刘布春, 孙忠富, 马浚诚, 郑飞翔. 基于探地雷达的田块尺度下不同深度土壤含水量监测[J]. 智慧农业(中英文), 2022, 4(1): 84-96.

ZHANG Wenhan, DU Keming, SUN Yankun, LIU Buchun, SUN Zhongfu, MA Juncheng, ZHENG Feixiang. Monitoring Specified Depth Soil Moisture in Field Scale with Ground Penetrating Radar[J]. Smart Agriculture, 2022, 4(1): 84-96.

参考文献

1	VEREECKEN H, HUISMAN J A, PACHEPSKY Y, et al. On the spatio-temporal dynamics of soil moisture at the field scale[J]. Journal of Hydrology, 2014, 516: 76-96.
2	VEREECKEN H, SCHNEPF A, HOPMANS J W, et al. Modeling soil processes: Review, key challenges, and new perspectives[J]. Vadose Zone Journal, 2016, 15(5): 1-57.
3	DE ROO R D, DU Y, ULABY F T, et al. A semi-empirical backscattering model at L-band and C-band for a soybean canopy with soil moisture inversion[J]. IEEE Transactions on Geoscience and Remote Sensing, 2001, 39(4): 864-72.
4	ZRIBI M, GORRAB A, BAGHDADI N, et al. Influence of radar frequency on the relationship between bare surface soil moisture vertical profile and radar backscatter[J]. IEEE Geoscience and Remote Sensing Letters, 2014, 11(4): 848-852.
5	PANCIERA R, TANASE M A, LOWELL K, et al. Evaluation of IEM, Dubois, and Oh radar backscatter models using airborne L-Band SAR[J]. IEEE Transactions on Geoscience and Remote Sensing, 2014, 52(8): 4966-4979.
6	韩东, 王鹏新, 张悦, 等. 农业干旱卫星遥感监测与预测研究进展[J]. 智慧农业(中英文), 2021, 3(2):1-14.
6	HAN D, WANG P, ZHANG Y, et al. Progress of agricultural drought monitoring and forecasting using satellite remote sensing[J]. Smart Agriculture, 2021, 3(2): 1-14.
7	LIU X, CHEN J, CUI X, et al. Measurement of soil water content using ground-penetrating radar: A review of current methods[J]. International Journal of Digital Earth, 2019, 12(1): 95-118.
8	HUISMAN J A, SNEPVANGERS J, BOUTEN W, et al. Mapping spatial variation in surface soil water content: comparison of ground-penetrating radar and time domain reflectometry[J]. Journal of Hydrology, 2002, 269(3): 194-207.
9	GROTE K, HUBBARD S, RUBIN Y. Field-scale estimation of volumetric water content using ground-penetrating radar ground wave techniques[J]. Water Resources Research, 2003, 39(11): ID 1321.
10	GALAGEDARA L W, PARKIN G W, REDMAN J D. An analysis of the ground‐penetrating radar direct ground wave method for soil water content measurement[J]. Hydrological Processes, 2003, 17(18): 3615-3628.
11	ALGEO J, VAN DAM R L, LEE S. Early‐Time GPR: A method to monitor spatial variations in soil water content during irrigation in clay soils[J]. Vadose Zone Journal, 2016, 15(11): 1-9.
12	王前锋, 周可法, 孙莉, 等. 基于探地雷达快速测定土壤含水量试验研究[J]. 自然资源学报, 2013, 28(5): 881-888.
12	WANG Q, ZHOU K, SUN L, et al. A study of fast estimating soil water content by ground penetrating radar[J]. Journal of Natural Resources, 2013, 28(5): 881-888.
13	曹棋, 宋效东, 吴华勇, 等. 探地雷达地波法测定红壤区土壤水分的参数律定研究[J]. 土壤通报, 2020, 51(2): 332-342.
13	CAO Q, SONG X, WU H, et al. Determination of basic parameters of soil moisture by using ground-penetrating radar ground wave method in red soil region of south China[J]. Chinese Journal of Soil Science, 2020, 51(2): 332-342.
14	李蕙君, 钟若飞. 探地雷达波振幅与土壤含水量关系的数值模拟[J]. 应用科学学报, 2015, 33(1): 41-49.
14	LI H, ZHONG R. Numerical study on the relationship between amplitudes of ground penetrating radar wave and water content in soil[J]. Journal of Applied Sciences-Electronics and Information Engineering, 2015, 33(1): 41-49.
15	CAO Q, SONG X, WU H, et al. Mapping the response of volumetric soil water content to an intense rainfall event at the field scale using GPR[J]. Journal of Hydrology, 2020, 583(C): ID 124605.
16	CHRISTIAN H, MARIA M, ELIZABTH V, et al. Understanding soil and plant interaction by combining ground‐based quantitative electromagnetic induction and airborne hyperspectral data[J]. Geophysical Research Letters, 2018, 45(15): 7571-7579.
17	ZHOU L, YU D, WANG Z, et al. Soil water content estimation using high-frequency ground penetrating radar[J]. Water, 2019, 11(5): ID 1036.
18	冉弥, 邓世坤, 陆礼训. 探地雷达测量土壤含水量综述[J]. 工程地球物理学报, 2010, 7(4): 480-486.
18	RAN M, DENG S, LU L. Review of measuring soil water content with ground-penetrating radar[J]. Chinese Journal of Engineering Geophysics, 2010, 7(4): 480-486.
19	ANDREA B. Water content evaluation in unsaturated soil using GPR signal analysis in the frequency domain[J]. Journal of Applied Geophysics, 2010, 71(1): 26-35.
20	HUISMAN J A, HUBBARD S, REDMAN J D, et al. Measuring soil water content with ground penetrating radar[J]. Vadose Zone Journal, 2003, 2(4): 476-491.
21	KATERINA Z, TOMAS C. Application of ground penetrating radar methods in soil studies: A review[J]. Geoderma, 2019, 343: 116-129.
22	ELIA S, ANTONIO B, PIETRO T, et al. Simultaneous monitoring of soil water content and salinity with a low-cost capacitance-resistance probe[J]. Sensors, 2012, 12(12): 17588-17607.
23	TOPP G C, DAVIS J L, ANNAN A P. Electromagnetic determination of soil water content: Measurements in coaxial transmission lines[J]. Water Resources Research, 1980, 16(3): 574-582.
24	ROTH C H, MALICKI M A, PLAGGE R. Empirical evaluation of the relationship between soil dielectric constant and volumetric water content as the basis for calibrating soil moisture measurements by TDR[J]. Journal of Soil Science, 1992, 43(1): 1-13.
25	HERKELRATH W N, HAMBURG S P, MURPHY F. Automatic real‐time monitoring of soil moisture in a remote field area with time domain reflectometry[J]. Water Resources Research, 1991, 27(5): 857-864.
26	FERRE P A, RUDOLPH D L, KACHANOSKI R G. Spatial averaging of water content by time domain reflectometry: Implications for twin rod probes with and without dielectric coatings[J]. Water Resources Research, 1996, 32(2): 271-279.
27	GREAVES, LESMES R J, LEE D P, et al. Velocity variations and water content estimated from multi-offset ground-penetrating radar[J]. Geophysics, 1996,61: 683-695.
28	OVERMEEREN R A, SARIOWAN S V, GEHRELS J C. Ground penetrating radar for determining volumetric soil water content; results of comparative measurements at two test sites[J]. Journal of Hydrology, 1997, 197(1): 316-338.
29	DIX C H. Seismic velocities from surface measurements[J]. Geophysicists, 1955, 20(1): 68-86.
30	HUISMAN J A, SPERL C, BOUTEN W, et al. Soil water content measurements at different scales: Accuracy of time domain reflectometry and ground-penetrating radar[J]. Journal of Hydrology, 2001, 245(1): 48-58.