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Examples of Resource Shed Map Series
July 1994
The
U.S. EPA used resource shed analysis to understand why nutrient loadings
from two similar storms on the Fox River watershed were so different.
The storms occurred July 4-8, 1994 and August 9-14, 1995. This figure
shows July 1994 resource sheds in the Fox River watershed.
In this example, the source distribution of July 4th rainfall that reaches the watershed mouth that day is depicted in the top row, far right: July 4th (a). The next line shows the source distribution of July 5th rainfall that reaches the watershed mouth that day (a), and also the source distribution of July 4th rainfall that reaches the watershed outlet on July 5th (b). On July 6th, we can see that rain from all three days is contributing to the outflow from the watershed (July 6 – a,b,c).
Despite the fact that there is no rainfall in the watershed for the period from July 9-12, as revealed by column (a) on each of those dates, we can see that there is still outflow during this period that originated from storm events on July 4- 8; e.g., see columns (e)-(i) on July 12th.
A glance at these resource shed maps makes it clear that the major source
areas from the July 4-8 storm are located in the southern to southwestern
portion of the Fox River watershed.
Compare these resource shed maps with those produced by a similar storm
that occurred in August,
1995.
Last updated: 2008-07-30