基于电磁感式大地电导率仪的南疆干旱区土壤电导率反演研究

Inversion of Soil Electrical Conductivity Based on Electromagnetic Induction Data in the Arid Region of Southern Xinjiang

土壤盐渍化是南疆农业和生态环境可持续发展的主要障碍因素。本文以南疆阿拉尔地区不同程度盐渍化土壤区域为研究对象,分析不同程度盐渍化及不同土壤水分含量区域土壤电导率电磁感应反演模型的差异,旨在为电磁感应技术应用于区域尺度土壤盐渍化监测提供有效的参考和借鉴。通过EM38-MK2电磁感应仪采集3个不同程度盐渍化土壤的电磁感应数据并同步采集土壤剖面样品,采用局部建模和全局建模的思路构建了土壤电导率的电磁感应反演模型。结果表明,土壤电导率电磁感应的线性模型、指数模型、对数模型和乘幂4种模型中,线性模型的精度最高。基于表观电导率数据所构建的土壤电导率局部模型精度优于全局模型,0~20、20~40、40~60 cm等不同深度土层局部模型的R2在0.78~0.89之间,全局模型则在0.70~0.80之间。土壤含水率对电导率电磁感应反演模型精度有明显影响,当土壤含水量小于10%时,土壤电导率电磁感应模型的R2为0.73,10%~20%时为0.85,大于20%为0.86。研究结果为同类地区土壤盐渍化的电磁感应监测提供了良好的借鉴。

Soil salinization is the main obstacle to the sustainable development of agricultural and ecological environment in southern Xinjiang.The difference in the electromagnetic induction inversion model of soil conductivity was analyzed among the Alar areasofsouthern Xinjiang with different degrees of salinization and soil moisture contents to provide an effective reference for the application of electromagnetic induction technology in soil salinization monitoring at the regional scale.EM38-MK2 electromagnetic sensor was used to collect electromagnetic induction data ofsoil profile samples.The electromagnetic induction inversion model of soil conductivity was constructed based on the ideas of local modeling and global modeling.The results showed that the linear model of soil electrical conductivity electromagnetic induction showed the highest accuracy.The local model of soil conductivity based on the apparent conductivity data was more accurate than the global model.The R2 of the local model and that of the global model atdifferent depths of 0-20,20-40,40-60 cm was between 0.78-0.89 and between 0.70-0.80,respectively.Soil moisture content varied with the precision of the electromagnetic induction model of soil conductivity.The R2 of the electromagnetic induction model of soil conductivity was 0.73,0.85 and 0.86 under the soil moisture content less than 10%,10%-20%,and greater than 20%,respectively.The results would provide a good reference for electromagnetic induction monitoring of soil salinization in similar areas.