Underwater detection and repair reinforcement technologies for reservoir-dam systems: development status and research challenges.

The long-term structural integrity of reservoir-dam systems is essential for ensuring water security, energy supply, and public safety. Underwater structural defects, driven by complex hydraulic and environmental conditions, pose growing threats to the safe operation of large dams. In recent decades, significant progress has been made in underwater inspection, defect detection, and repair technologies, offering viable alternatives to traditional drawdown-based maintenance. This review systematically synthesizes advances in underwater detection and rehabilitation technologies for reservoir-dam systems, focusing on inspection platforms, positioning and navigation methods, defect identification techniques, and underwater repair materials. It critically examines key challenges, including limited transferability of marine-derived technologies, environmental interference, cumulative operational errors, and real-world applicability. This paper further categorizes existing technologies by maturity and proposes problem-oriented research directions to support the development of intelligent, reliable, and field-deployable systems for underwater defect management in large dams.