Author(s): S. Kemper; A. Schlenkhoff; J. Balmes
Keywords: No keywords
Abstract: Managing urban flooding caused by heavy rainfall events requires new design approaches concerning the drainage system as well as the temporary surface water runoff. Latest developments on bidirectional coupled models–considering the surface water runoff and the sewer discharge–are still employed in practice. Connecting elements between the surface and the underground drainage system are the so called street inlets or gullies–offered in different construction types and designs. Depending on the longitudinal and transversal slope of the street as well as the street inlet type the hydraulic efficiency of grate inlets (typically used in Germany) is hardly available, thus, physical model test runs were done to receive the requested information. Due to steep longitudinal slopes up to 10%, only supercritical flow conditions occur with flow depths up to 3 cm and flow velocities of approximately 1–2 m/s. The intercepted flow varies between Q I =2.95l/s and Q I =16.00l/s within the investigated model test runs. With three-dimensional numerical model test runs, the capacity of the underground system (sump with sludge bucket and connection pipe) to cope with the intercepted surface flow is analyzed. Several conditions–clogging effects as well as different pressure heads in the pipe system–were investigated. Based on the results from the numerical model test runs, a chart was developed to identify the maximal possible inflow from the surface to the underground system.