Embedding landscape processes into triangulated terrain models

Triangulated irregular networks (TIN) can form the basis for multiple-resolution representations in distributed hydrogeomorphic simulations over complex basins. Current methods for deriving TIN meshes depend primarily on surface slope without considering other terrain attributes significant to the watershed response such as the specific basin area. As an alternative, we present a methodology for combining a hydrogeomorphic or landscape index with an unstructured triangulated mesh. Landscape indices provide a concise method for describing steady-state terrain processes by isolating the dominant physical factors. The mesh-generation algorithm results in an adaptive discretization that resembles the spatial pattern of the landscape index with a high resolution retained in areas expected to impact the basin response. We compare the proposed algorithm with a slope-preserving method as a means for initializing the terrain representation in two TIN-based hydrogeomorphic models. Through three case studies in saturation-excess runoff, transport-limited soil erosion and shallow landslide simulation, we assess the distributed model sensitivity to the triangulated terrain algorithm. Model comparisons reveal that the process-based triangulations focus the distributed simulation in regions anticipated via a steady-state index to affect the transient watershed response.