Landflow: Computer program for the numerical simulation of two-dimensional overland flow

A finite-element program for the integration of the two-dimensional diffusion-hydrodynamic model (DHM), governing surface flow in shallow water, is presented. The program uses, as an option, either a control-volume finite-element (CVFE) or a Galerkin finite-element (GFE) formulation. Different methods for computing the transmissivity and capacity terms are compared on the basis of the global mass-balance error for both the GFE and the CVFE formulation of the model. The discretisation of the flow domain is obtained by using triangular finite-elements and linear shape functions, whereas integration in time is performed by a finite-difference (FD) Picard scheme. Remarkable improvements of the global mass-balance error can be obtained by using the different methods in computing the transmissivity and capacity terms. The listing of the computer code written in FORTRAN 77 along with the user manual are available by anonymous FTP from IAMG.ORG. Some numerical examples are presented for comparing, on the basis of global mass-balance errors, the performance of six schemes of the CVFE method with that of the equivalent GFE formulations. (C) 1997 Elsevier Science Ltd.