I think here in the Netherlands this is also done for a couple of years now [1]. Apparently they also used a "waste" product of steel manufacturing for it inste

I think here in the Netherlands this is also done for a couple of years now [1]. Apparently they also used a "waste" product of steel manufacturing for it instead of just rocks. No idea if it was because of this experiment. [1] https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming-tegen-het-water/maatregelen-om-overstromingen-te-voorkomen/vooroeververdediging https://www.rijkswaterstaat.nl/water/waterbeheer/bescherming...