Apalachicola-Chattahoochee-Flint (ACF) System Reservoirs during Hurricane Irma

Hurricane Irma made landfall in Florida on September 10, 2017.  This post details impacts on four reservoirs on the ACF System.

These reservoirs are formed by Buford Dam (Lake Lanier), West Point Dam, WF George Dam, and Woodruff Dam (Lake Seminole).

The location of the dams is shown in the figure below.



7-day QPFs are shown below for the following time periods:

September 8, 2017 at 8:00 pm to September 15, 2017 at 8:00 pm.
September 9, 2017 at 8:00 pm to September 16, 2017 at 8:00 pm.

For both forecast time periods, the potential rainfall amounts appear to be greater for the area around Buford Dam than for the other three dams.





The pool elevation at Lake Lanier for the month of September 2017 is shown below (from Corps of Engineers website).  The top of conservation at Lake Lanier varies from elevation 1070 ft to 1071 ft depending on time of year.  The pool level at Lake Lanier was in conservation pool prior to Hurricane Irma and remains in the conservation pool after its passage with only about a 0.4 foot rise occurring.


The pool elevation for West Point is shown below.  The summer level conservation pool is elevation 635.0 ft.  West Point elevation rises from elevation 631.5 ft (3.5 ft below top of conservation) to just over 635.0 ft moving slightly into the flood pool.


 In the plot below, it can be seen that West Point pool elevation drops steadily from mid-August until the inflow from Hurricane Irma causes a rise.  The plot below is updated through September 12, 2017 so the actual rise to top of conservation is not yet shown.  The drop in elevation throughout the summer months is not unexpected as can be seen from the historical median elevation.  West Point Dam has power production as one of its conservation demands.

  
The pool elevation at WF George is shown below.  This pool experienced slightly less than a 2 foot rise and remains below the top of conservation elevation of 190 ft.  Recall that outflow from West Point Dam becomes inflow to WF George and contributes to this rise.


Lake Seminole (formed by Jim Woodruff Dam) has a tight operating range that normally falls between 76.5 feet and 77.5 feet.  The pool elevation for Lake Seminole during the first half of September 2017 is shown below.





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