树干水分分布及运移的高密度电阻率成像法时空监测  

Temporal and spatial monitoring of water distribution and migration in a tree trunk using electrical resistivity tomography

作　　者：吴华桥[1] 周启友[1] 刘汉乐[1] 

机构地区：[1]南京大学水科学系地球科学系,南京210093

出　　处：《地球物理学进展》2008年第4期1310-1316,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(40371021)资助

摘　　要：在砍伐树干周围四个特定高度环形布置一定数量的金属电极,测定了对应横截面上各点视电阻率,再利用有限元反演计算,获得了树干各截面上电阻率的空间分布图像.由于树干内的水分含量和对应部分的导电特性密切相关,可以从得到的电阻率平面分布图上反映出树木内水分含量的空间分布和动态变化特征.结果表明,树干横截面上电阻率的空间分布呈现一系列的同心圆结构,且从核心部到外边缘的韧皮部电阻率有一个减小的趋势,说明截面内树木水分的含量沿径向向外有逐渐递增的趋势.时间变化过程中,各监测截面上的电阻率的分布和变化基本反映了截面水分的流逝过程,表明高密度电阻率成像法动态监测树干水分分布及变化是可行的.Arranging a ring array of metal electrodes at four sections of different height around a cut tree trunk, we measured the internal 2D apparent resistivity distribution of the corresponding section. Based on the apparent resistivity distribution, the section＇s electrical resistivity distribution is then determined using a finite element inversion method. In fact, tree moisture content, slightly mineralized, can be clearly reflected because it shows a close inverse relationship with electrical resistivity. The result indicales that the tree trunk always shows a concentric ring structure with a central maximum of resistivity, decreasing to the periphery, corresponding to an increase of moisture from the inner dry heartwood to the outer wet ring of sapwood. The resistivity distribution at different sections reflects the temporal and spatial variations of water migration, indicating that dynamic monitoring of water distribution and migration in the tree trunk using electrical resistivity tomography is reasonably feasible.

关 键 词：高密度电阻率成像法 树干 含水率 水分分布 

分 类 号：P631[天文地球—地质矿产勘探]