Remote Sensing Approach to Upstream Slope Inspection: Fid-Bau Portal

Remote Sensing Approach to Upstream Slope Inspection

Shoemaker, Travis A. / McGuire, Michael P. / Roussel, Guilaine

Many conventional inspection practices for dams and levees place heavy demands on limited human resources. Furthermore, traditional inspections of riprap slope protection material rely on qualitative evaluations that involve a degree of subjectivity. The combination of these factors can result in incomplete and inaccurate assessments of the riprap condition over time. This paper presents a novel method for inspecting riprap slope protection material using three-dimensional (3D) point cloud data captured by lidar or photogrammetry. The method has been validated using two full-scale studies, a laboratory-scale study using gravels, and extensive two-dimensional (2D) numerical simulations. The validation shows that the small-scale topography of the slope face, known as roughness, is correlated to the median size of the riprap. Thus, as the riprap weathers and breaks into smaller pieces, the roughness of the slope will decrease. The roughness is a quantitative parameter that enables spatial analysis of the riprap condition over time. The studies performed to date indicate that this method can be used on slopes having an approximately planar face, clear of significant vegetation and debris, and armored using end-dumped riprap with a coefficient of uniformity not exceeding 2.5. The slopes of many operational dams and levees meet these criteria, making this a practical inspection tool that can target limited inspection resources to where they are most needed. The basics of the method are demonstrated using a field trial conducted at a reservoir in the northeastern United States.