Measuring the flow intrusion towards building areas during urban floods: Impact of the obstacles located in the streets and on the facade

Abstract

This paper provides, through laboratory experiments, the flow discharge passing from a flooded street to a building area through different types of damaged openings (a door, a window and a gate) along with a sensitivity analysis of this discharge to the presence of obstacles or facade details. Four flow regimes in the street are tested, representing a high or low street slope with a high and low water depth. These flows resemble that over rectangular side weirs, with the major difference that obstacles are usually located near the opening in the street or on the facade. 26 configurations of obstacles are then included, one after the other, and their impact on the flow intrusion is measured. For the flow cases without obstacle, the agreement of the semi-analytical equations available in the literature strongly varies from one equation to another. On the other hand, the 220 tested flow cases reveal that the location of the obstacle with regards to the opening strongly modifies the impact of the obstacles, that increasing the Froude number tends to increase the impact of the obstacles and that obstacles have a higher impact on the intrusion discharge through a window than to a door or a gate. Finally we conclude that the largest obstacles (typically parked cars) located in the vicinity of openings should be somehow included in operational numerical models that calculate urban floods for a fair prediction of the intrusion discharge.