The delineation of resource sheds can also be applied to open waters, but the physics are completely different. Rather than being constrained within the upland watershed, a resource shed in open water is defined by currents. Here the application of time is especially important, as we have to impose a time period over which to consider the movement of water .The figure is an empirical demonstration showing the spatial distribution of nutrients in Lake Erie. Resource sheds, or source areas, for locations indicated by crosses show that uneven distribution of nutrients is caused by water from different sources meeting in the Lake. The model for this work was developed by Dr. Joseph Atkinson. Products include: Raikow et al. 2010.