Watershed Delineation with Triangle‐Based Terrain Models

An algorithm is presented for tracing the path of steepest descent from a given starting point on a terrain model defined by a triangulated irregular network. This algorithm is then extended to solve several problems. The flow patterns for a site are generated by tracing flow paths from a large number of starting points. The approximate stream network or channel network is found by tracing the channels upstream from pits or exit points. Once the stream network is found, the source areas or contributing areas for each of the sections of the stream are delineated. The source areas are then used to delineate the watersheds of selected nodes in the channel network. The format of a possible data structure for the channel network is presented along with pseudocode examples for traversing the channel network and the source areas. Execution times on a desktop computer are presented along with suggestions for optimal use of the algorithms.