Recent remote underwater surveys: Advances in methods and rechnologies for structural assessments of dams and spillways

This paper examines recent advances in technologies and methods for remote underwater structural surveys of dams. Various inspection cases are included to show how imaging and multibeam sonar, photogrammetry, underwater laser, and HD video can be used to bolster a facility’s permanent record while adding an invaluable contribution to risk assessment data. Processes for calculating volumes are discussed, be they loss of eroded material or debris and sediment accumulation. The presentation covers-issues such as sonar range and resolution, positioning and navigation, hydro-acoustic and other methods-for leak detection, as well as new technology such as GPR for void detection behind penstock and tunnel-liners and concrete condition assessments. Examples of sonar renderings, multiple and disparate types-of date sets stitched together, and other reporting methods are included.