Gravel river banks. The gravel stones (grey) in the river and on the banks have been washed to their present location following recent rainfall. This is part of a re-naturing project aiming to prevent flooding. The previous approach of using dams and reinforced river banks damaged the river and led to extensive flooding when the banks were broken or over-topped. This approach of using banks of gravel that allow the river to reshape itself is more sustainable and less damaging, and helps to prevent severe flooding. This is the Thurgau part of the Thur River, Switzerland.