21 feet of water

The great flood of 2009 is over, and I made my first trip to the park after the waters receded. They called this a 500 year flood, and I can believe it. Upstream from the park we received over 18 inches of rain. That water had to go somewhere, so it flooded the Chattahoochee River. The road that I use to access the northern side of the park was flooded and closed in four places. The evidence is easy to see - the muddy water left marks on the trees and vegetation like a dirty bathtub ring.

From Chattahoochee Bend

My totally unscientific survey of the flood in the bend of the River reveals that it was 21 feet above normal level on the east side of the bend and 20 feet on the west side. The high water mark is easy to find. The obvious floodplain was underwater to a depth of maybe 10 feet. I came up with the answer of 21 feet by counting the LIDAR contours on my basemap. The difference between the east side and west side probably has to do with the topography. An area between 300 and 400 meters from the riverbank was flooded. That's a lot of water.

I'm not going down in there to look at it more closely. The news is full of reports that millions of gallons of raw sewage got washed down from Atlanta. I think I will at least wait for the leaves to fall to go back into the floodplain - every leaf is coated with mud. I could see plenty of standing water too.

So I stayed up on the "hills" in the center of the bend. I put "hills" in quotes because they look like hills on the map, but when you are standing there it can be difficult to tell. The contours are very gentle, and cannot really be used for precision navigation. They are covered with a confusing assortment of randomly-shaped fields, pine plantations, green areas, and forest. Not confusing enough to fool an expert orienteer, but I think they will cause some significant head-scratching. There is plenty of this area to keep me occupied until the leaves fall and the flood waters dry out.

From Chattahoochee Bend

Another problem is that now I need to recheck those areas of floodplain that I did before the flood. I haven't done that much, and it was over where the hills make their closest approach to the river. It can't be helped though. At least there have not been significant new blowdowns and resulting rootstocks.