Experimental campaign to determine grated inlet clogging factors in an urban catchment of Barcelona

Urban drainage systems have two different drainage layers, one superficial and another underground, that are connected through drain inlets and manholes. Specifically, a collection system is formed by inlets distributed throughout a basin, with the function of collecting and directing the surface runoff into sewers. Generally, the hydraulic characterisation of the inlet system considers the grates in an ideal state, free of dirt and debris obstructions, although often this is not the case. In these cases, clogging effects should be considered as a reduction in terms of hydraulic efficiency. The aim of this paper is to present a methodology to determine, quantitatively, the hydraulic efficiency reduction of partially clogged grated inlets. With this aim, clogging patterns for the most common grated inlets operating in Barcelona (Spain) were defined and experimental tests at real scale were carried out in order to determine the hydraulic efficiency reduction due to clogging phenomena.