Abstract
The authorsp reviouslyp roposeda new type of manholeb for energy lossr eduction with a flat guide cover on the invert of a coventional manhole with right-angle pipes (2000).How ever, when rainfall in an urban area significantly exceeds the design valuef or rainfall on the storm sewer network, flood damage is unavoidable even if the energy losses at manholes in the area have been reduced. It might be possible to reduce floodd amage in these areas by increasinge nergy losses at manholesupstream, and the intentional overflow from these manholes may delay the spread of flow over the ground surface downstream.The authors also previously proposed a new type of manhole with a bafflep late at the manhole outlet in straight pipes in order to reduce the cross-sectionaal area of flow to the downstream pipe.Under steep solpeg round surface, “drop” is often set between upstream and downstream pipes. In this study, the energy loss coefficient, K is estimated by experimental data in manholes considering four kinds of baffle plates snd three kinds of drops. The energy loss coefficient, K ranges from 0.8 to 8.9 due to the experimental results.
