There is no content to display.
Posted by Bill Dennison.
Bob Hirsch and co-workers at the U.S. Geological Survey have developed a new method of analyzing long-term trends in nutrients that enter Chesapeake Bay from the rivers or tributaries that flow into the Bay. This method accounts for seasonal changes and year-to-year variation in flow, so that one can see the “forest for the trees.” The difficulty in analyzing flow and nutrients that enter Chesapeake Bay is the high degree of variability (or noise) in the data, making it difficult to discern trends, particularly long-term trends. Bob was able to use daily water flow data over a 31-year period, stretching from 1978 until 2008 from nine sites around Chesapeake Bay. Bob took these 100,000+ daily streamflow measurements and combined them with 13,000+ nutrient measurements to come up with daily nutrient loading estimates at each site. Then he was able to calculate a “flow-normalized daily flux,” which takes out the variations in flow due to weather. In this way, the long-term trends could be distinguished from the short-term variations. Continue Reading