Thursday, February 05, 2009

More Beach Graphs

Here's something I believe we need more of down on SPI - beach transects. Imagine if you sliced the beach due east and measured the distance to the beach as well as the elevation. This transect was done in 2005 or so on a place called "SPI02," which I have no idea where that is. But with the new dredge stuff, constant erosion, and probably storms, it's nice to graph these over time and see how things are changing.

In this graph, the sea wall is where measurements are taken. You'll see a hump for a nice dune or two, and then a hump in the middle called the fore-dune. The vegetation line is on the right side of the fore-dune. The rest is all public beach down to the water line.

The horizontal scale is not perfect because I'm a dummy with the new Excel software but that's 300 feet from the condo seawall (historic building line) to the waterline, not bad. Note that this was before the erosion events that occurred later in 2005 due to Katrina and Rita, which would be cool to compare.

I also backwards engineered this graph to show that it is almost exactly 7 feet from the waterline to the top of the seawall - usually the survey numbers are negative and in meters, which are a little tough to read. The 300 feet is a magic number though, as erosion will cause that to dramatically shorten.

Think this is tough stuff requiring professionals? They have students trained at Point Isabel High School who do this all the time!


Lucinda said...

Thanks for this, Sam. Why don't we have a whole bunch of graphs like this readily available? How can we do a good job of protecting our beaches when we are not regularly using info like this?

Sam said...

I've tried the usual suspects like A&M, GLO, and HDR Shiner-Mosely, and getting online information is very hard and often so difficult to interpret I gave up.

But I think with Dr. Heise at UTB and some high school kids at Point Isabel, we might be able to get routine data like transects, vegetation cover, washover areas, and important stuff like that.

I'll ask Rob over at Surfrider if he'd be interested. Actually, "shooting" a transit with GPS is really cool beans, hi-tech. But difficult? No, it's almost too simple, just getting your feet sandy.