What type of waterway gate did Leonardo da Vinci improve for canals?

Leonardo da Vinci improved the canal lock's miter gate design.

A miter gate consists of two gates that meet at an angle pointing toward the higher water level. Water pressure pushes the gates together, helping them resist the force without requiring the hinges to carry the entire load. Leonardo studied and refined this type of gate for canal engineering in Milan.

His work is associated with the San Marco canal lock, where he helped develop practical improvements to navigation infrastructure. Canal locks allow boats to move between water levels by filling or emptying an enclosed chamber. The technology was already known before Leonardo, so he was an improver and engineer rather than the inventor of every lock principle.

Leonardo's notebooks show sustained interest in water flow, gates, canals, pumps, and hydraulic machines. These studies connected mathematical observation with the needs of Milan's waterways.