What are the protusions in the Elbe river near Hamburg, Germany?

When you make a river too straight it totally screws up the ecology of the river. I think those help keep the water moving around more naturally. I could be wrong.

They’re called groins. They’re quite controversial as they tend to cause erosion. You can read about them here: http://chl.erdc.usace.army.mil/chl.aspx?p=s&a=ARTICLES!188

Ah, guess I was wrong, looked like they might be for the benefit of the river based on the picture. Thanks Ashpea!

Well, sometimes they benefit by nourishing the banks of the rivers/oceans, but if they’re not built correctly they can cause massive erosion very quickly. The Cape Hatteras lighthouse controversy is a good example of that, if you’re interested. And the only reason I know about something as random as groin fields is because I took an environmental issues class last year, and those were one of the things we covered. This is actually the first time I’ve actually used any knowledge I gained from that course, so I’m pretty excited! :P

Haha, nice, I am interested. Thanks for the extra info!