Part of the water volume of a river or canal can be diverted around the city to prevent flooding during high water levels in the built-up area. This requires digging a new river arm or canal. This is a very costly and drastic solution. It can be combined with nature development and other functions.
In order to protect Nijmegen from high water, a side channel is being dug in the bend of the Waal in the floodplains, the project Room for the Waal. This project is part of the program Room for the River. This is a program of the Department of Public Works in which more than 30 places more space is made for the rivers to prevent flooding.