We present an existence theorem for a shallow-water problem with a dep
th-mean velocity formulation and non-homogeneous boundary conditions e
xpressing water entering. A result has been already shown in the case
of homogeneous boundary conditions. If we prescribe a non-zero velocit
y (or normal velocity) on the boundary, we must also prescribe the wat
er elevation on the part of the boundary where the flow enters. With t
hese boundary conditions, we obtain a priori estimates that show the p
roblem has a solution. We build a sequence of approximated solutions t
hat preserves energy and to pass to the limit we use a trace theorem f
or the space of L(-1) -functions with L(-1) -divergence.