Effective lake length

The effective length of a lake is the longest straight connection, i.e. (geometrical) route , between two bank points that are only determined by it and that only crosses the water surface, i.e. does not intersect any islands or peninsulas . The longest stretch at right angles to it, which also connects two points on the bank without going over land in between, is called the effective width . Both serve as an indication of how strong the water of the lake can be moved by winds.

In the case of narrow and curved or highly articulated lakes, the effective length can be significantly less than the shortest connection between the most distant bank points (which kinks at least once in such lakes).

The product of the effective length and the effective width can differ significantly from the lake area (in m², ha or km²).

source

• Federal Environment Agency: Research report 299 24 274 “Documentation of the condition and development of the most important lakes in Germany”, May 2004, PDF for download , p. 17: “The effective length describes the connection line between the two most distant points on the shoreline, without Land (peninsulas, or islands) to be crossed. These describe the real distance from bank to bank without land in between. ”(The definition could possibly also be interpreted differently, but the one described in the article text is the practical application.)