SPECIAL ISSUE “Roles of Revegetation for Preventing Sediment Disaster ”
Detection of horizontal root distribution of a black pine in a sea coast by concentrically searching of ground penetrating radar

Abstract

Horizontal root distribution of a black pine in a sea coast was detected by ground penetrating radar because it is important information for evaluating disaster reduction function of a tree. In this study, we aimed to (1) extract roots from radargram collected by concentrically searching line, (2) estimate horizontal root distribution by taking root connection into account, (3) evaluate root extraction accuracy by comparing the results with birds-eye view of the dug up pine roots. We extracted roots from the radargram using contrast and wave-form information, and found that real roots existed under the 76％ of the extracted locations. Horizontal root distribution estimated from the connection of root extraction points indicated 5 of 7 horizontal roots matched with real roots wholly or partly. These results suggest that ground penetrating radar is a useful tool for estimating potential distribution of horizontal roots of black pine in sea coast. We also examined the influence of wave-form shape and clearness of waveform contrast on extraction accuracy. Our results showed that more than 70％ of the waveform that had strong contrast and / or parabolic waveform. successfully extracted roots. This suggests the information of waveform is effective for extract roots from radargram.