Analysis and calculation of sediment scouring rate at different locations of storm sewer

Abstract

To explore the migration differences of sediments at the front, middle, and end sections of a storm sewer when scoured by water, and further evaluate the pollution load, the scouring process of sediments at different locations of a storm sewer was simulated and mathematical models were built to calculate the scouring rate. Results show that scouring rate is affected by sediment particle size, pipeline slope, sediment thickness, and water flow velocity. As the slope increased, scouring rate at the end section increased more obviously. The scouring rate at the front section slightly decreased with increasing sediment thickness, but opposite trends were observed at the middle and end sections. When the particle size (0.33 mm–0.83 mm) and flow velocity (0.15 m/s–0.65 m/s) increased within their ranges, scouring rate increased across all three locations. Models for calculating scouring rate were established via two data fitting. The calculated values were compared with measured values at a scouring time of 1 min. Under different particle sizes, the difference between the calculated and measured values at front, middle, and end sections were in the ranges of −0.63% to 0.63%, −0.01% to 0.02%, and −0.13% to 0.16%, respectively, all of which showed good consistency. HIGHLIGHTS The increase of scouring rate at end section is more obvious as slope increases.; Scouring rate of all the three locations increases with flow velocity increasing.; Scouring rate is great when particle size is big (d50 = 0.33–0.83 mm).; Scouring rate at different locations in a storm sewer is calculated using models.; Difference between the calculated and measured values is from −0.63% to 0.63%.;

Keywords

• calculation model
• scouring rate
• sediment
• storm sewer