Before revision: → See also salt marsh Drainage (Pump) mill on a dyke at the Overwaard Polder near Kinderdijk Because a koog or polder often lies below the level of the adjacent sea or river, it has to be continually drained.
After revision: → See also salt marsh Drainage (Pump) mill on a dyke at the Overwaard Polder near Kinderdijk Because a koog often lies below the level of the adjacent sea or river, it has to be continually drained.