TERRAIN-BASED CATCHMENT PARTITIONING AND RUNOFF PREDICTION USING VECTOR ELEVATION DATA

An automated method of partitioning catchments into interconnected elements using a "stream tube" approach and vector or contour-based digital elevation models is briefly described. With this form of partitioning, hydrologic models can be structured based on the hydraulics of flow within a catchment and the effects of topography on runoff producing mechanisms and spatially distributed flow characteristics (such as flow depth and velocity) can be directly, and realistically, accounted for in the models. The method allows complex three-dimensional flow problems to be reduced to a series of coupled one-dimensional problems in areas with complex terrain. Two simple process-oriented hydrologic models that demonstrate the utility of this form of partitioning are presented. The first models subsurface flow-saturation overland flow and the second models Hortonian overland flow. Observed and predicted runoff hydrographs and the dynamic expansion and contraction of runoff source areas on a small laboratory microcatchment are presented. Also shown are predicted runoff hydrographs and surface flow velocities on a small rangeland catchment in the United States.