Florida's Suwannee River had a record low year.
|Hydrographs help us better understand the present|
Take for example discharge, the top hydrograph.
Do you see where it literally "dropped off the chart" for much of 2011?
While the multi-colored hydrograph at the top may appear to be difficult to read at first, I would argue that anything less is an incomplete painting at best. The sharp blue line is current discharge. However, a current condition is insufficient alone if it not painted relative to historical statistics and ecological thresholds that define it. That's what the background color coding and shading provide. Not only can you see where the river has been for the past year and a half, you can also look ahead to how far waters need to climb to make it back up to a normal spring. Now lets move to the bar chart at the bottom. It shows annual discharge volume of the Suwannee (as measured at Ellaville) from 1940 to present in millions of acre feet per year. 2011 is the tiny bar on the far right which, if you look back in time, is the lowest flow year going back more than sixty years.
Why use Ellaville as the definite site?
I locked in on Ellaville because it reaches so far back in time.
|This calendar chart transports us back into deep time|
The calendar chart above is plotted in the same color scheme as the hydrograph at the top. Red triangles indicate times of very low flow (under 1,000 cubic feet per second). As you can see, there is quite a long string of those for 2011. You may also note that the river's traditional spring peak has been lower (and delayed) in recent years in comparison to the past few decades.
So why is the Suwannee River so low?
Is a climactic shift in play? Or was the lingering effects of a La Niña desiccated spring? Maybe ground-water pumping plays a role? This data set is a good start, but we would need more to know for sure.