Mapped differences in weighted wind fetch distances within the Upper Mississippi River System between 1989 and 2011

Wind fetch is defined as the unobstructed distance that wind can travel over water in a constant direction. Fetch is an important characteristic of open water because longer fetch can result in larger wind-generated waves. The larger waves, in turn, can increase shoreline erosion and sediment re-suspension. 

A baseline conditions assessment of wind fetch was conducted to assist the Upper Mississippi River Restoration program's Long Term Resource Monitoring element (LTRM) in identifying areas within the river system where excessive wind fetch could be a problem. This was accomplished using three separate years of land cover/land use data developed by the LTRM (1989, 2000, and 2010/2011). Wind fetch from 36 directions (10 degree increments) was developed and then a weighted wind fetch output was developed. Additionally, separate outputs were developed calculating the difference of weighted wind fetch between 1989 and 2000, and also the difference between 2000 and 2010/2011.