Drainage 101

The process of adding water to an area

The process of measuring water flow in a river

The process of removing excess water from an area (correct)

The process of purifying water

Subsurface drainage

Surface drainage

Sprinkler irrigation (correct)

Open ditch drainage

To prevent waterlogging and flooding (correct)

To purify water for drinking

To increase water levels in an area

To measure water flow in a river