Siepen, Siefen, Seifen or Seipen are typical regional words used in northwestern Germany for what are often narrow, wet, ravine-like V-shaped valleys of the German Central Uplands with their small headstreams.
In North Hesse the term is found in the old Lower Saxon dialect area in the counties of Waldeck-Frankenberg to Korbach and Bad Arolsen.
[6] The form -siepen (with a p) as part of the name of waterbodies or places is, by contrast, mainly found in the northern Bergisches Land as far as south Westphalia.
In the post-glacial period the quantities of water flowing out of the Central Uplands were greater, so that the streams were able to cut down more strongly into the terrain than they are today.
It is possible that there is an etymological relationship between the Middle Low German term for a similar fluvial landform, sike , and the word Siepen.