  Modeling and simulating overland flow fed by rainfall is a common issue in
watershed surface hydrology. Modelers have to choose among various friction
models when defining their simulation framework. The purpose of this work is to
compare the simulation quality for the Manning, Darcy-Weisbach, and Poiseuille
friction models on the simple case of a constant rain on a thin experimental
flume. Results show that the usual friction law of Manning is not suitable for
this type of flow. The Poiseuille friction model gave the best results both on
the flux at the outlet and the velocity and depth profile along the flume. The
Darcy-Weisbach model shows good results for laminar flow. Additional testing
should be carried out for turbulent cases.
