Abstract
Recently localized torrential rain has hit many urban areas to cause inundation partly owing to the insufficient drainage capacity of sewer system. Drain cover or grating, which serves as an inlet of road runoff to sewer system, needs to have high drainage capacity to minimize inundation. This study demonstrates through experiments that the introducing component members to conventional grating can significantly enhance its drainage capacity over a wide range of incoming discharge and road slope. Flow visualization and velocity measurement have shown that the enhancement is realized by the rectangular shape of the component member to alter the coming flow downwards and that the decrease in velocity over the grating due to the component member is too small to explain the increase in drainage capacity.
