摘要
探地雷达地波法是一种农田尺度快速测量土壤体积含水量的有效技术,能够弥补传统方法和卫星遥感方法在含水量监测上的不足。但地波法在红壤地区进行含水量反演的最佳参数仍未确定,相关研究鲜有报道。本研究以位于南方红壤区江西省鹰潭市孙家流域为例,采用地波法对区域土壤体积含水量进行了探测:先使用共中心点法确定所用雷达的系统延时、有效反演深度,并利用Topp、Roth、Ferre和朱安宁四种常用的经验模型由介电常数ε反演土壤含水量;然后通过固定间距法进行区域性的土壤体积含水量测量,确定雷达测量时的最佳天线间距。这一系列过程中,土壤含水量实测值是用烘干法校正的管式时域反射仪(time domain reflectometry,TDR)测定的土壤体积含水量。研究的目的是为了律定地波法在红壤区测定土壤含水量的有效反演深度、最优模型和最佳天线间距等参数。结果表明:60 MHz探地雷达地波法反演0~40 cm土层的土壤体积含水量时精度最高,误差最小;Roth经验模型更适合于红壤地区0~40 cm土层土壤含水量的反演,均方根误差(root mean square error,RMSE)为0.022 m3m-3;地波法的最佳天线间距为1.0 m,能够准确地反演土壤体积含水量;土地利用类型对雷达的探测精度具有一定影响,在1.0 m天线间距下,旱地上的反演精度优于果园,旱地和果园的RMSE分别为0.004和0.020 m3m-3。
As a widely used geophysical technique,Ground Penetrating Radar(GPR)has special advantages,such as non-destructiveness and high accuracy,for measuring soil water contents at the field scale.Well,Ground wave method is the combination of common midpoint(CMP)and fixed offset(FO)measurements based on GPR.However,the optimum parameters of ground wave method greatly varied across different areas and remained unclear for red Soil.Therefore,to achieve the optimal parameters for ground wave method for red Soil,GPR survey under the CMP and FO modes was conducted in the Red Soil Critical Zone Observatory(Yingtan).The collection of CMP soundings aimed to determine the time-zero calibration,effective sampling depth and petrophysical relationships.The antennae spacing was optimized under the FO mode.These parameters were incorporated into four empirical models(i.e.,Topp,Roth,Ferre and Zhu Anning).The predictions were evaluated based on the observations measured by time domain reflectometry(TDR).The results showed that the most accurate predictions were achieved at 0-40 cm soil depth.The Roth empirical model outperformed other methods with a root mean square error(RMSE)of 0.022 m3 m-3.The predictions were more accurate in the upland than that in the orchard under the suitable antenna separation of 1.0 m.These parameters may benefit the soil moisture estimation in the similar areasand may supply more information for terrestrial modeling and precision agriculture.
作者
曹棋
宋效东
吴华勇
张甘霖
杨顺华
CAO Qi;SONG Xiao-dong;WU Hua-yong;ZHANG Gan-lin;YANG Shun-hua(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of sciences,Beijing 100049,China)
出处
《土壤通报》
CAS
CSCD
北大核心
2020年第2期332-342,共11页
Chinese Journal of Soil Science
基金
国家自然科学基金项目(41571130051,41771251)
国家重点研发计划项目(2018YFE0107000)资助。
关键词
探地雷达
土壤含水量
地波法
共中心点法
固定间距法
Ground penetrating radar
Soil water content
Ground wave method
Common midpoint
Fixed offset
