May 15, 2013

Hydrograph flummoxed (but not surprised)

Sometimes hydrographs don't tell the full story:

Even when they are jam packed with all the information they can hold.

The above hydrograph shows current stage in Lake Okeechobee relative to ecological and historical statistics.  For example, current stage (blue line) is plotting right on top of the 20-year median (dotted white line) for mid May, which in ecological terms puts the wetting from in the middle of the littoral zone, i.e. interior levee wetlands, and in engineering terms is about a foot and a half below the base of the perimeter levee.

The hydrograph of Lake Okeechobee above would appear to indicate that lake stage is just right -- not too high and not too low. But just last week I read an article by Andy Reid in the Ft Lauderdale Sun Sentinel (view article here) that the U.S. Corps of Engineers was preparing to release water out of the lake into the downstream estuaries as a precaution against coming wet season rise. More commonly we call that wasting water to tide and also polluting the estuary, too.

The flip side is that it helps ensure the structural integrity of the perimeter levee.


Water management decisions are increasingly multi-use and inevitably zero sum games.

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