Problem: When engineers place concrete groynes and plant vegetation on top of the groynes along the bank of a river, what are they trying to achieve? Group of answer choices The hope is that groynes are buried by the next major flood event. Groynes are trying to encourage river erosion right next to the cement, to "shoot" the sediment rapidly down the stream. They are family members of local politicians who were unemployed prior to awarding such make-work projects. The groynes are to prevent the river from becoming too sinuous (or meandering) and erode banks. The structure are trying to keep the river in a fairly straight channel.