基于探地雷达波振幅包络平均值确定土壤含水率  

Detection of soil water content using ground penetrating radar average envelope amplitude method

作　　者：吴志远[1,2] 彭苏萍[1] 杜文凤[1] 崔凡[1] 

机构地区：[1]中国矿业大学(北京)煤炭资源与安全开采国家重点实验室,北京100083 [2]中国矿业大学(北京)地球科学与测绘工程学院,北京100083

出　　处：《农业工程学报》2015年第12期158-164,共7页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然基金煤炭联合项目资助项目(U1261203)

摘　　要：为了评估探地雷达探测地表土壤含水率的准确性,该研究使用雷达波振幅包络平均值(average envelope amplitude,AEA)方法在室内对含水率为0.05、0.15及0.25 cm3/cm3的砂质土壤进行了探测,并与时域反射仪(time domain reflectometry,TDR)所得土壤含水率进行了对比。结果表明,在实验室内,在0.05、0.15及0.25 cm3/cm3的土壤含水率条件下,使用AEA方法探测所得土壤含水率均比TDR所得含水率大,均方根误差分别为0.026、0.015及0.01 cm3/cm3,这3个含水率条件下,AEA方法探测土壤水分的有效深度分别为0.9、0.6和0.3 m。利用AEA方法在野外进行地表含水率探测,并与TDR和钻孔取样探测的地表含水率进行对比。野外探测结果表明,AEA方法所得含水率与TDR探测所得含水率的均方根误差为0.020 cm3/cm3,与取样实测所得含水率的均方根误差为0.031 cm3/cm3,使用AEA方法能够得到与TDR及钻孔取样精度相近的土壤含水率分布图。研究表明利用探地雷达AEA方法在探测浅部地层土壤含水率是可行的。Soil water content measurement is an important and tedious task,and the ground penetrating radar（GPR） technique has been used for soil water content distribution estimation.The GPR is a fast and nondestructive tool,capable of providing information of electromagnetic wave propagation.The conventional methods of GPR for detecting soil water content mainly include the air direct wave method,the surface direct wave method,the reflected wave method and the borehole GPR method.Because the electromagnetic wave attenuation in aqueous medium is fast,the air direct wave method and the surface direct wave method can only detect the soil water content near the surface,and these models are vulnerable to interference,and difficult to determine the zero take-off time,so the detection results are always not accurate.Reflection wave method is widely used at present,but it requires clear reflector in the scope of radar wave propagation,and it is difficult to apply in complex underground area.The borehole GPR is mainly suitable for the detection of soil moisture content in small scale.The radar wave average envelope amplitude（AEA） method is to find out the radar average amplitude envelope signal value having the best correlation with the shallow strata dielectric constant by analyzing and establishing the relationship between the radar early-time average amplitude envelope signal value and shallow strata dielectric constant.The instantaneous amplitude has been computed by considering the amplitude of the Hilbert transform of signals simulated by a typical common-offset configuration,using the value of average envelope amplitude calculated in different early-time windows to back calculation the dielectric constant,then the Topp formula is used to calculate the soil water content.In order to assess the accuracy of GPR in detecting the surface soil moisture content,early-time ground penetrating radar signal AEA method is used to detect the sandy soil with water contents of 0.05,0.15 and 0.25 cm3/cm3 in laboratory.Comparing the

关 键 词：雷达 土壤 含水率 地质雷达 雷达波振幅包络平均值 时域反射技术 

分 类 号：S152.7[农业科学—土壤学]