Saturday, August 4, 2018

The Flip Side of Dune Stabilization: Dunes Unleashed in Central Oregon

In our last post, we had a look at the "carpeted" dunes of Florence, the ridges of wind-blown sand along the coast that have been "stabilized" by invasive European Beach Grass. The grass was planted in the 1920s and has spread from California to British Columbia. It's a real problem, and huge changes have taken place in the geography of the dune environments along the west coast, especially  at Oregon Dunes National Recreation Area.

The beach grass has displaced native plants and animals, and caused massive foredunes to rise above the beaches. The inland areas behind the foredunes became starved of sand, forming deflation basins where pools and lakes formed and forests thrived. These are all problems for the original ecosystem of the dunes, but there is the flip side: the stabilization of the dunes was done for a reason.

Not all of the dunes in the Florence region are covered by dune grasses. Sand that blew away from the deflation basin formed dunes on the eastern edge of the dune field and many of those dunes have not been covered by beach grasses. The dunes are still active, migrating eastward with the prevailing wind. And that's a problem, at least in some areas.

I was at a shopping center in town on a recent trip, and I wasn't having much fun (it was Christmas shopping or some such thing), but I had noticed the dune sands behind the complex and headed out to have a look. The sand ridge was huge and so steep I had to really search to find a spot to climb to the crest. I huffed and puffed my way up and was presented with the awesome view of clean dunes and a distant lake in the deflation basin (the picture at the top of the post).

But the crux of the sand problem was the steepness of the dune behind the store complex. It was  steeper than the angle of repose (the natural angle of the sand slope). It was immediately obvious that the huge pile of sand was encroaching onto the business complex, and there was a lot of sand. The dune tops were twice as high as the building. There is an ongoing battle to stop or slow the movement of the sand.

It looks like they've been bulldozing sand, undercutting and increasing the slope of the dune. It's no doubt an expensive fix, but falling back to the "solution" of the 1920s would be unthinkable today. The movement of sand is unrelenting, and there will always be problems at the back of this business complex.

Our sojourn in Florence was about to end. We didn't quite know what lay ahead, since we had only a single camp reservation for one night for the next four days. We were going vagabonding, a tradition (and sometimes a source of stress!). More to come...

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