  Floods are one of the deadliest natural hazards and are fueled by excessive
urbanization. Urban development decreases infiltration by reducing pervious
areas and increases the accumulation of pollutants during dry weather. During
wet weather events, there is an increase in the levels of pollution
concentrations and stormwater runoff that eventually reach creeks and rivers.
Polluted stormwater runoff may be sources of water supply. Modeling the
quantity and quality dynamics of stormwater runoff requires a coupled
hydrodynamic module capable of estimating the transport and fate of pollutants.
In this paper, we evaluate the applicability of a distributed hydrodynamic
model coupled with a water quality model (HydroPol2D). First, the model is
compared to GSSHA and WCA2D in the V-Tilted catchment, and the limitation of
the critical velocity of WCA2D is investigated. We also applied the model in a
laboratory wooden board catchment, focusing on the validation of the numerical
approach to simulate water quality dynamics. Then, we apply HydroPol2D in the
Tijuco Preto catchment, in Sao Carlos - Brazil, and compare the modeling
results with the full momentum solver of the Hydrologic Engineering Center -
River System Analysis (HEC-RAS). The model implementation, the governing
equations, and the estimation of input data are discussed, indicating the
challenges and opportunities of the application of distributed models in
poorly-gauged catchments. For a 1-yr return period of rainfall and antecedent
dry days and assuming an uncertainty of $40\%$ in the water quality parameters,
the results indicate that the maximum concentration of total suspended solids
(TSS), the maximum load and the mass of the pollutant washed in $30\%$ of the
volume are, $456~\pm~260~\mathrm{mg.L^{-1}.km^{-2}}$, $\mathrm{2.56 \pm
0.4~kg.s^{-1}.km^{-2}}$, and $\mathrm{89\%~\pm~10\%}$, respectively.
