The ability to regulate the outflow from the lakes does not mean that control of lake levels is possible. Neither can they be accurately predicted to be planned for. The effects of the natural fluctuation of water supply to the lakes far exceed any impact human activity has had. Return to the Table of Contents Littoral Transport and Sand Supply. Erosion is part of a larger process known as littoral transport.
Littoral transport is the movement of material by waves and currents on the coastline.
The material being transported is primarily sand and gravel, with a small percentage of silt-sized particles and rocks. The source or supply of nearly all of the sand that is in the littoral transport system of the Great Lakes is from the erosion of the bluffs and dunes. Very little material is supplied by rivers. Littoral transport occurs both along the shoreline, as well as into the lake and onto the shore. With respect to sand supply, a given length of coastline may have a surplus, be in balance, or have a deficit in its sand supply budget.