岳宁, 董军, 李玲, 阚飞, 王刚, 黄少文, 魏国孝. 基于高密度电阻率成像法的陇中半干旱区土壤含水量监测研究[J]. 中国生态农业学报(中英文), 2016, 24(10): 1417-1427. DOI: 10.13930/j.cnki.cjea.160304
引用本文: 岳宁, 董军, 李玲, 阚飞, 王刚, 黄少文, 魏国孝. 基于高密度电阻率成像法的陇中半干旱区土壤含水量监测研究[J]. 中国生态农业学报(中英文), 2016, 24(10): 1417-1427. DOI: 10.13930/j.cnki.cjea.160304
YUE Ning, DONG Jun, LI Ling, KAN Fei, WANG Gang, HUANG Shaowen, WEI Guoxiao. A soil water content monitoring in Longzhong semi-arid region by high-density electrical resistivity tomography[J]. Chinese Journal of Eco-Agriculture, 2016, 24(10): 1417-1427. DOI: 10.13930/j.cnki.cjea.160304
Citation: YUE Ning, DONG Jun, LI Ling, KAN Fei, WANG Gang, HUANG Shaowen, WEI Guoxiao. A soil water content monitoring in Longzhong semi-arid region by high-density electrical resistivity tomography[J]. Chinese Journal of Eco-Agriculture, 2016, 24(10): 1417-1427. DOI: 10.13930/j.cnki.cjea.160304

基于高密度电阻率成像法的陇中半干旱区土壤含水量监测研究

A soil water content monitoring in Longzhong semi-arid region by high-density electrical resistivity tomography

  • 摘要: 土壤含水量是影响半干旱区农作物生长的重要因素。为了准确测定土壤含水量的变化动态以指导农业高效用水, 近年来, 利用地球物理测量方法研究高分辨率的水流入渗, 已经越来越受到欢迎和重视。本文以陇中半干旱区玉米田为例, 通过在土壤表面布置电极, 利用高密度电阻率成像法(ERT)对降雨前后土壤二维剖面进行电阻率数据测量, 实现对土壤二维剖面电阻率值和含水量监测, 解释不同条件下土壤含水量变化的原因, 建立陇中半干旱区农田土壤电阻率和含水量之间的相关关系。结果表明: 降水入渗使得二维剖面土壤电阻率整体呈明显降低趋势, 反演得到的电阻率图像局部电阻值“高低高”的变化过程, 与一次降水过程前后“干湿干”的循环过程一致。土壤含水量实测值与估计值之间有较为显著的线性关系(R2=0.651 8, n=96)。在0~2.0 m深度范围内, 总体估计偏差较小, 为0.74%; 土壤含水率的估计精度较高, 为2.64%。0~0.5 m土层(H1)含水量监测探头分布密集, 数据采集较为准确, 故H1层估计精度略高于0.5~2.0 m层(H2)。相比之前利用实测工具进行野外测量, ERT测量方法精度较高。本文提供了一个高分辨率的土壤结构二维分布与水分运移过程的图像, 同时为实现精确和高效的农业用水管理提供一种新途径。

     

    Abstract: Soil water content (SWC) is a key factor influencing crop growth in semi-arid regions. Monitoring the variations in SWC is critical for agriculture. In recent years, geophysical survey has been used in the study of high-resolution detection of water infiltration and it is hugely popular because of its zero-damage to soil micro-structure and easy measurement. With a maize field in Longzhong semi-arid region as the case study, we used high-density electrical resistivity tomography (ERT) to measure (before and after the precipitation) two-dimensional electrical resistivity of the column of soil below an electrode placed on the soil surface. Then SWC and electrical resistivity were monitored in two-dimensional soil profile in order to explain the variations in SWC under different conditions and to determine the correlation between electrical resistivity of each soil horizon and its water content in Longzhong semi-arid region. Soil temperature was also discussed in the ERT data interpretation. The results revealed the potential of ERT to improve soil and agronomic studies. Vertical distributions of two-dimensional electrical resistivity image inverted from measured data were different. On the whole, natural rainfall infiltration reduced the trend in two-dimensional electrical resistivity. The trend of local electrical resistivity of the inverted ERT images was one of “high-low-high”, quite consistent with the “dry-wet-dry” cycle of the precipitation process. Two- dimensional sections of SWC calculated using ERT showed a reliable linear correlation (R2 = 0.651 8, n = 96) between the estimated and measured SWC in the root-zone horizon, with a slope approximately equal to 1. Within the depth range of 02.0 m, the precision of the calculated specific SWC quantified by the root mean square error (RMSE) was 2.64%, with a bias corresponding to an overestimation of 0.74%. The densely distributed SWC detectors installed in the H1 horizon (00.5 m) enhanced precise data collection, resulting in better measurement accuracy than in the H2 horizon (0.52.0 m). The study also discussed the factors responsible for the deviation between measured SWC and estimated SWC. The development and adoption of precision farming and rational irrigation required detail knowledge of soil and crop. The method used in this study was useful in the research and description of high-resolution soil spatial variability and hydric characteristics. Additional field calibration was required for applying the method practical on routine field application. The use of general petro-physical relationship between soil electrical resistivity and its moisture, if appropriate, could bring the method a step closer to practical field application for the purpose of improving irrigation management.