Modeling sediment capture efficiency of roadway inlets for a range of slopes and flow regimes

The urban drainage system is designed and built to effectively convey the rainfall-runoff out of the urban area to prevent inundation and local flooding, which can cause property damage and affect traffic and human safety. Inlets play a critical role in routing stormwater off of roadways and into stormwater infrastructure. As stormwater enters inlets it brings sediments associated with the runoff, that may result in maintenance to the inlet or downstream infrastructure overtime. There has been extensive laboratory research focusing on highway stormwater inlets and their capture efficiency. However, there is relatively little research focusing on the ability of inlets to capture sediments. Taking advantage of Computational Fluid Dynamic (CFD) modeling and flume experiments, this study explored flow and sediment capture efficiency of roadway inlets. A proof-of-concept was developed using Fluent, a CFD model, to evaluate the efficiency and hydraulic properties under various flow conditions and inlet geometries. The study involved physical and numerical modeling of flow over a rough surface with varying cross and longitudinal slopes for various flows and for a fixed geometry, to understand sediment capture of inlets. This CFD model was calibrated and validated using flume experiments with 3D printed inlet geometries. The findings of this study provide insight into the function and efficiency of stormwater inlets and aid in improving sediment capture through the inlets and within the urban landscape.