Thread: Floodwatch
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Old Posted Mar 22, 2011, 1:56 PM
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Join Date: Feb 2009
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Quote:
Originally Posted by jimsabo21 View Post
Well, here is my question: In 2009 the city surverying crew came over and placed stakes in our yard showing the different levels. Basically, the bottom of our walk-out basement was 22.5 ft above James. So, they made us build a sandbag dike (2 ft) in front of the walk out only.

The water actually rose to 22.6 ft at James that year; however, the water was nowhere near our dike - in fact, it was 30 ft away from our house. In reality, the water would have to have risen an additional foot (23.5 ft James) for it to hit our dike.

So, in my estimation, whatever the reading is at James, you have to subtract 1ft for our area. Just wondering if you've noticed the same thing?
I'm going to assume you were not there in 1997.

You can't use 2009 as any kind of a reference. It was a strange flood year that was caused more by ice than water. Localized ice jams caused strange level readings. Plus you have to remember that during high periods the surface of the river isn't "flat", i.e. it will back up and be higher behind restrictions like shallow areas and sharp turns.

Surveys are usually pretty close. If your dike was higher than needed it was probably because it was built with two feet of freeboard as they always are. Level predictions are just that - predictions. During the 1997 "Red Sea" event the engineers said one inch of rain in the flood area meant one foot of additional water in the city!

I can't remember what the slope of your yard looks like but when you say the water was 30 feet away, what was the vertical dimension? If the water goes up one foot it can eat up the yard quickly if it is a gentle slope.

Listen to the engineers and build the dike as they specify. Too high is better than too low!
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