Preliminary Use of Ultrasonic Tomography Measurement to Map Tree Roots Growing in Earth Dikes

Abstract

The aim is of this study to find a relevant criterion to detect and map tree roots in the surrounding soil. In each following ex- periments, we studied properties of propagation, espacially velocity and attenuation of amplitude, as parameters to discriminate the root from the soil. Our work has been initiated on laboratory experiment with an ultrasonic transmission device to highlight relative differences between samples of soil and roots. Measurements were repeated on different root samples (species, dimension, decomposition time) to cover the diversity encountered on dikes. Then an intermediate state device reproducing in-situ conditions in laboratory was performed at the soil surface in two plastic tank containers: one control of bare soil and another containing a root sample burried in homogeneous soil. We shown with laboratory experiments that information provided by the velocity term seems relevant to localize roots in the soil for healthy root samples. Same conclusion was derived from tanks study where significant variations of velocity were observed due to root presence.