ROV Inspection Checklist for Dams: Gates, Intakes, Sediment and Crack Documentation

Dams and hydraulic structures need regular underwater inspection. Over time, gates, intakes, outlet works, walls and trash racks may face cracks, corrosion, sediment build-up or hidden damage. However, these areas are often hard and risky for divers to reach. An ROV can make the work safer and more efficient. With cameras, lights, sensors and stable control, a dam inspection robot can collect clear visual data while operators stay on the surface. In addition, recorded video and images can support future repair plans and asset records. PELAGIX develops ROV systems for dam inspection, subsea operations, environmental monitoring and underwater infrastructure work. The following dam inspection ROV checklist can help teams plan a more complete and useful inspection. Why Use an ROV for Dam Inspection? Underwater dam areas can be dark, narrow and full of debris. Also, water flow near intakes, gates and outlets can create extra risk. For this reason, many teams use ROV systems before sending divers or maintenance crews. A hydraulic structure ROV can help inspect key areas without draining the reservoir. It can move close to concrete surfaces, steel parts and intake screens. Moreover, it can record video evidence for engineers, owners and repair teams. As a result, ROV inspection supports safer work, faster checks and better documentation. Pre-Inspection Planning Checklist Before the ROV enters the water, the team should prepare the mission plan. Good planning reduces missed areas and helps the inspection run smoothly. Check the following items: - Define the inspection goal - Confirm dam layout, depth and access points - Review past inspection reports - Mark gates, intakes, outlets and known risk areas - Check weather, water level and flow conditions - Confirm ROV depth rating and tether length - Test cameras, lights, thrusters and recording tools - Prepare communication between the operator and site team - Set emergency recovery steps - Prepare file names and report templates This step is important because a clear plan leads to a better ROV inspection report. Gate Inspection Checklist Dam gates control water flow, so their condition matters. A small issue can affect operation, safety and long-term service life. During gate inspection, use the ROV to check: - Gate surface condition - Corrosion, rust or coating loss - Cracks near welds or joints - Deformation or misalignment - Seal condition - Debris around the gate - Wear near guide slots - Leakage signs - Loose or missing parts - Marine growth or biofouling In addition, record close-up video of any abnormal area. If possible, capture both wide views and detailed shots. This makes later review easier. Underwater Intake Inspection Checklist Underwater intake inspection is one of the most common dam ROV tasks. Intakes may collect branches, trash, sediment and aquatic growth. If the blockage grows, water flow and equipment performance may be affected. Inspect these intake areas: - Trash racks and screens - Intake openings - Guide frames - Grates and bars - Blocked or damaged sections - Sediment near the intake base - Debris trapped around the structure - Signs of cavitation or erosion - Corrosion on metal parts - Cracks around concrete edges Also, check whether the ROV can view the intake from several angles. A front view may not show all blockage. Therefore, side and lower views can provide better detail. Sediment and Debris Checklist Sediment can change water flow and reduce storage or intake performance. It may also hide damage at the base of the structure. Because of this, sediment checks should be part of every dam inspection robot checklist. Document the following: - Sediment depth near gates and intakes - Silt build-up around walls and corners - Sand or gravel movement - Debris piles - Branches, cables or foreign objects - Blocked drainage or outlet areas - Changes compared with past records If the ROV has sonar or measuring tools, use them to support visual findings. Even when only video is available, clear footage can help engineers decide whether cleaning or dredging is needed. Crack and Concrete Surface Documentation Concrete cracks can be small at first, but they need careful tracking. ROV video can help teams document cracks and compare changes over time. When checking concrete surfaces, look for: - Horizontal, vertical or diagonal cracks - Spalling or broken concrete - Surface erosion - Exposed reinforcement - Leakage stains - Joint damage - Honeycombing - Impact marks - Unusual color changes - Areas with loose material For crack documentation, keep the camera steady. Move slowly and record the surrounding area first. Then take a closer view of the crack. If a scale tool is available, place it near the defect for size reference. Hydraulic Structure ROV Route Checklist A planned route helps the operator cover the full inspection area. It also reduces the chance of missing important details. A useful route may include: - Start point and entry check - General overview of the dam face - Gate inspection path - Intake inspection path - Outlet and spillway areas - Base and sediment zones - Known defect locations - Return and recovery path In addition, the team should mark time stamps for key findings. This makes the ROV inspection report much easier to prepare. What to Include in an ROV Inspection Report A clear report turns underwater video into useful action. It should be simple, visual and easy for engineers to review. An ROV inspection report should include: - Project name and inspection date - Dam or structure name - Water level and weather conditions - ROV model and camera setup - Operator and inspection team - Inspection route - Photos and video references - Finding locations - Defect type and severity - Notes on gates, intakes, sediment and cracks - Suggested follow-up actions - Comparison with past inspections, if available Also, include still images from the video. Short captions can explain what each image shows. How PELAGIX ROV Systems Support Dam Inspection PELAGIX focuses on advanced underwater intelligent equipment, including AUVs, ROVs, underwater sensors, software systems and technical services. Its ROV products support underwater inspection, environmental monitoring, dam inspection and subsea operations. For dam inspection, a PELAGIX ROV can help teams view submerged structures in real time. With stable movement, lighting and payload options, the system can support visual checks of gates, intakes, walls and sediment zones. This makes ROVs a practical tool for routine checks, emergency inspections and repair planning. Conclusion Dam inspection requires clear planning and careful documentation. Gates, intakes, sediment zones and concrete cracks all need close attention. However, many of these areas are difficult and risky to inspect by hand. A dam inspection ROV checklist helps teams work in a more organized way. It supports safer underwater intake inspection, better defect records and more useful inspection reports. With the right hydraulic structure ROV, dam owners and service teams can find problems earlier, reduce risk and make smarter maintenance decisions.