Flushing Out Sediment
• Sponsors: Iowa Department of Transportation (IDOT)
• Objective: To develop a culvert design that prevents blockage by sedimentation and vegetation — a self-cleaning system that would flush out the sediment deposits using the power of the stream flow itself.
Research Goals:
- Understand the mechanics of the sedimentation process at culverts for various flow events
- Meet the IDOT’s requirements for a new solution to the problem of sedimentation in culverts
Refining the Geometry
Sedimentation: A problem for midwestern multi-box culverts
- Multi-box culverts are frequently blocked by sediment deposits and vegetation, but the mechanics of the sedimentation process had not previously been studied
- This sediment blockage can obstruct the flow and cause the culvert to overtop during storms, producing local flooding and property damage
- Clean-up is costly in terms of time and effort, and must be repeated often at many culvert sites
- Muste first built 1:20 scale three-box culvert models to test new designs. Next, he used numerical simulations to refine the geometry and test them under a range of flow conditions. Finally, Muste and his team implement the solution in situ and has monitored operations there since 2013. The fillet-based design has performed well at natural scale
How Can a Culvert Clean Itself?
- The successful self-cleaning culvert design is “fillet-based,” meaning that the channel leading up to the culvert entrance is shaped to better resemble the natural cross-section
- The fillets are set on the stream bottom immediately upstream of the culvert.
- They slope toward the banks to bring the culvert site back to the original streambed shape
- The fillets direct the sediment through the central barrel and restrict the extent of low-velocity areas on the sides that are prone to sedimentation
- This design maintains the effectiveness of the flow conveyance over a range of flows
