Naturalization of Urban Streams Using In-Channel Structures

Channelization limits the geomorphological and biological diversity of many urban streams. This paper presents a pool-riffle design for straight urban streams where existing infrastructure prevents re-alignment of channel planform. The design of the pool-riffle units is the result of a multi-disciplinary approach, which includes ecological, geomorphological and engineering aspects. The proposed structures fulfill four main requirements: they increase flow variability during low and moderate flows; they produce minimal increase in the water levels during high flows; they self-maintain in terms of bed erosion and sediment deposition, and they provide in-stream habitat for fish. The hydraulic performance of the design was tested at two different scales using two existing models: FLOW-3D at the pool-riffle unit scale and HEC-RAS at the reach scale.