Question: what are dikes and polders?
Answer: A polder (Dutch pronunciation: [ˈpɔldər] ( listen)) is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are: Land reclaimed from a body of water, such as a lake or the seabed. Flood plains separated from the sea or river by a dike.