In some areas of the LA River, modifying the existing channel is advantageous for flood risk reduction, access, and/or ecological function. Channel modifications may include terracing the banks that can serve as stairs, amphitheaters, or small planting trays. Other channel modifications include changing the materiality or shape of the channel, for example, adding or removing concrete, deepening or widening the channel or going from trapezoidal to vertical wall, depending on capacity requirements.
The existing LA River channel is comprised of 13 different channel configurations which vary in shape, width, and depth. Some sections have a rectangular section with vertical sides, while other segments are trapezoidal with tapered sides. Historically modifications to the channel have primarily been made to increase the capacity of the channel.
Trapezoidal Channel Cross Section
Trapezoidal Channel: Channel Modifications.
OLIN, 2019.
Box Channel Cross Section
Box Channel: Channel Modifications.
OLIN, 2019.
Benefits
Depending on the channel modification implemented, benefits might include improved access and safety, making places for people and habitat, and improving channel capacity to reduce flood risk.
Considerations
Any channel modification requires hydraulic analysis to ensure flood risk is not increased. Additionally an analysis of existing ecological functions associated with the channel is important to assess potential impacts brought about by the modification.
