CRPC-TR98764 May 1998 Title: Finite Element Approximations to the System of Shallow Water Equations, Part III: On the Treatment of Boundary Conditions Authors: Clint N. Dawson and Monica L. Martinez Submitted September 1998; Available as TICAM Report 98-15 Abstract: We continue our investigation of finite element approximations to the system of shallow water equations, based on the generalized wave continuity equation (GWCE) formulation. In previous work, we analyzed this system assuming Dirichlet boundary conditions on both elevation and velocity. Based on physical grounds, it is possible to not impose boundary conditions on elevation. Thus, we examine the formulation for the case of Dirichlet conditions on velocity only. The changes required to the finite element method are presented, and stability and error estimates are derived for both an approximate linear model and a full nonlinear model, assuming continous time. Stability for a discrete time method is also shown. ------------------------------------------------------------------------------ Clint N. Dawson Monica L. Martinez clint@ticam.utexas.edu monicam@ticam.utexas.edu Texas Institute for Computational and Applied Mathematics University of Texas at Austin