sUAS Remote Sensing for Closed-canopy Tree Inventory on Earthen Dams

Abstract

More than half of the U.S. dams are privately owned and experienced the overgrowth of trees. There is a need to improve dam inspection and maintenance in a timely manner. Small Unmanned Aircraft Systems (sUAS) have been increasingly utilized for near-surface landscape mapping and reconnaissance. This study tests an sUAS protocol of closedcanopy tree survey on earthen dams. A DJI Matrice 100 flight was launched on September 22, 2020. The orthoimage and 3D point cloud are extracted, and the canopy height model is built. Treetops and crowns are delineated using an integrated watershed segmentation and image segmentation procedure. The results include a tree survey inventory that contains the locations, tree heights and crowns of 284 trees growing on the downslope of the dam. Given the flight flexibility and fine 3D details acquired from inexpensive drones, sUAS has a high potential for assessing tree overgrowth toward remediation solutions of earthen dams.