Within the framework of this work, a one-dimensional shallow water model including Suspended Solid (SS) transport on urban surfaces was developed. This model allows an evaluation of TSS load and TSS concentration in water effluent at kerb localization. The effects of road slope, road surface granularity, friction, rain intensity can be measured, in particular through pollutogram analysis, to progress in the understanding of the processes at stake. Preliminary results show that rain intensity and variability introduced by the irregularities of the substrate are key processes involved in pollutant runoff. First flush effect appears to be closely linked to road granularity. Model outputs have to be further validated to improve urban water quality hydrological models used at larger scale.