Reducing Detention Volumes with Improved Outlet Structure

To reduce required detention volume, a detention basin outlet structure (DBOS) was tested that can control the maximum allowable outlet discharge rate independent of the upstream driving head. Unlike traditional outlet control structures, such as culverts, orifices, and weirs, whose maximum discharge represents a single point in time on the outflow hydrograph, the DBOS can discharge at the maximum allowable discharge for an extended period of time, thus reducing the required detention volume. Data are presented and methods discussed regarding techniques for altering the head–discharge characteristics of the DBOS in order to meet various head–discharge requirements.