Hydraulic Efficiency of Grate and Curb Inlets - Urban Drainage and ...

45.0
40.0
35.0
Captured flow (cfs)
30.0
25.0
20.0
15.0
10.0
5.0
0.0
0 0.2 0.4 0.6 0.8 1 1.2
Gutterline flow depth (ft)
5 ft 9 ft 12 ft 15 ft
Figure 4-6: Type R curb inlet sump test data
Several general trends can be found in the sump test data:
• For a given flow depth, a longer inlet results in higher captured flow.
• As the flow depth increases, the corresponding captured flow increases.
• For a given inlet length, the Type 13 inlet is generally the most efficient, followed by
the Type 16 and Type R.
4.3 Summary
A sample of the collected data set was presented in tabular form and all of the data
presented in graphical form. The entire data set in presented in Appendices B and C. Qualitative
observations were made regarding the nature of flow in the model and performance of the inlets
tested. For the on-grade tests, flow velocity and depth were found to be the primary influencing
parameters on efficiency. Street longitudinal slope primarily affected flow velocity, and cross
slope primarily affected the spread of flow across the model street section. A detailed regression
analysis of the on-grade test data, development of design equations, and qualitative observations
are presented in the analysis chapter of this report.
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