A tidal wave….always a scary thought, and usually associated with the ocean, however, tidal waves or “seiches,” can occur in enclosed bodies of water as well, such as a lake— like that of “big water,” or Lake Okeechobee.
As we have entered hurricane season and live in Florida, the most vulnerable state in the nation for strikes, it is important that all of us in the St Lucie River/Indian River Lagoon/Lake Okeechobee region know our evacuation plan should one be necessary….
A while back, I wrote about my frightening experience with a storm in the proximity of Lake Okeechobee and my friend, Dr Gary Goforth, wrote me back. Today I will share his thoughts on the subject of “tidal waves” in Lake Okeechobee.
Since “we” first walled the lake for agriculture in the 1920s, “white man” has changed the dynamics of both water and of storms….Recently, the ACOE has spent over 65 million dollars to repair the aging dike. As you know, nature evolved so Lake Okeechobee’s overflow waters would slowly flow south to the Everglades. This is no more, and her overflow waters are directed with great destruction through the Northern Estuaries…
So now about seiches…..or tidal waves…..
History & Today/Herbert Hoover Dike: (http://www.saj.usace.army.mil/Missions/CivilWorks/LakeOkeechobee/HerbertHooverDike.aspx)
FROM DR GARY GOFORTH (http://garygoforth.net)
Your comments on the “tidal waves” within the Lake inspired me to chart the fluctuations in water levels in the Lake resulting from the 2004 hurricanes Frances and Jeanne…
The attached images below show two charts and a reference map.
The first chart shows the fluctuation in Lake stage as Hurricane Frances slowly moved through the area and the 2nd is a similar chart for Hurricane Jeanne. An interesting feature is that as the storm approached the Lake, strong north winds blew the water to the southern rim against the HHDike (as reflected by the rising red line: water level along the south shore) and simultaneously moved water away from the northern sections of the Dike (as reflected by the descending blue line: water level along the north shore). This phenomenon contributed to the catastrophic flooding south of the Lake in the 1926 and 1928 storms as the muck dike failed. For Hurricane Frances, the water level along the south shore rose by more than 5 ft as the eye approached!
As the eye of the storms passed over the Lake, the wind quickly changed direction and the water that was piled up along the south shore moved to the north rim of the Dike (rising blue line). For Hurricane Frances, the water level along the north shore rose by 10 ft or more when the winds shifted! For Hurricane Jeanne, which was moving faster than Frances, the water level on the north shore rose by more than 4 ft per hour – I suspect it looked like a slow-moving tidal wave coming towards the Dike!
For both storms, the water levels overtopped the stage gauges at both stations – so the fluctuations were actually greater than depicted in the charts!
For more information, you can read up on Lake seiches (http://en.wikipedia.org/wiki/Seiche) which are large waves sloshing back and forth in large bodies of water.
—Gary, Dr Goforth 4/15
Thank you Dr Goforth for an interesting lesson. Let’s all be safe and smart this hurricane season.