  We establish the local-in-time well-posedness of classical solutions to the
vacuum free boundary problem of the viscous Saint-Venant system for shallow
waters derived rigorously from incompressible Navier-Stokes system with a
moving free surface by Gerbeau-Perthame. Our solutions (the height and
velocity) are smooth (the solutions satisfy the equations point-wisely) all the
way to the moving boundary, although the height degenerates as a singularity of
the distance to the vacuum boundary. The proof is built on some new
higher-order weighted energy functional and weighted estimates associated to
the degeneracy near the moving vacuum boundary.
