Modeling the Seasonal Dynamics of Surface Water Networks Using DEM

The topology and spatial extent of regional surface-water bodies fluctuate seasonally, with the most pronounced changes during high-intensity rainfall and flooding. To capture these dynamics, we introduce a novel geomorphological metric, the catchment-to-destination area ratio (C/D ratio). The catchment area represents the upstream contributing surface area, and the destination area represents the spatial extent of the receiving sink, such as a depression or existing water body. Theoretically, the C/D ratio scales proportionally with the rate of water-level (stage) rise in destination basins during wet seasons. As water levels increase, the lateral expansion of receiving basins drive fundamental topological shifts in watershed-network connectivity. Using the C/D ratio and upstream catchment area, we develop a computational simulation algorithm for modeling the seasonal and climate-driven evolution of surface-water configurations from digital elevation models (DEMs). The algorithm distinguishes natural topographic depressions from spurious digital artifacts, supports automated channel routing across low-relief terrain, preserves two-dimensional channel widths, and estimates depression storage capacity for flood-buffer assessment. Evaluation across multiple DEM datasets demonstrates the algorithm’s ability to simulate seasonal variation of the watershed network and identify flood-prone terrain configurations. This framework allows predictions for regional flood-hazard mapping, water-resource planning, and environmental and ecosystem management. Available at https://cs.stanford.edu/people/zjl/flow.