Analysis of the Effect of Clogging of Road Grate Inlets Due to Poor Construction and Lack of Strength on Drainage Efficiency and Momentum

Abstract

As urban flooding damage increases due to the increases in heavy rain owing to climate change, the need for research to prevent urban flooding damage is increasing as well. In this connection, because of poor grate construction, the positions of the upper and lower grate inlet spheres are not fixed, or the entrance is narrowed owing to damage caused by a lack of strength, which impedes drainage efficiency. To investigate this effect, we quantitatively analyzed the drainage efficiency and momentum according to the degree of clogging of the grate inlet using a two-dimensional numerical simulation, finding that the clogging of the grate inlet due to the two flow rate cases was increased by 25% p each. Furthermore, the drainage efficiency and momentum by water depth and flow velocity after clogging were quantitatively analyzed through a two-dimensional numerical simulation. As the clogging increased by 25% p, the drainage efficiency decreased to approximately 25–26% p, while for momentum, all cases with low flow rates were clogged, or the momentum tended to continue to increase along the longitudinal slope. However, at high flow rates, the maximum momentum was obtained when the longitudinal slope was 2%. These results are expected to contribute to the prevention of damage from urban flooding through the efficient management of runoff in urban areas by providing quantitative evidence on the necessity and efficiency of grate inlet management to prevent urban flooding.