Fetch (geography)

Fetch, often called the fetch length, is a term for the length of water over which a given wind has blown. It is used in geography and meteorology and is usually associated with coastal erosion. It plays a large part in longshore drift as well.

The fetch length along with the wind speed (or strength) determines the size of waves produced. The longer the fetch length and the faster the wind speed, the larger and stronger the wave will be. For example, the winds which travel from the East Coast of the United States and hit the west coast of Ireland would have an extremely large fetch and would produce very large waves if the wind speed was also high.The fetch length determines the power and energy of the wave. Additionally, if the winds are blowing in the same direction during the wave's lifetime, the wave will in turn be stronger. If a fetch is very large, then the wave will be very large and vice versa. The fetch is related to the orbit of the wave.