Abstract
In traditional watershed delineation and topographic modeling, surface depressions are generally treated as spurious features and simply removed from a digital elevation model (DEM) to enforce flow continuity of water across the topographic surface to the watershed outlets. In reality, however, many depressions in the DEM are actual wetland landscape features with seasonal to permanent inundation patterning characterized by nested hierarchical structures and dynamic filling-spilling-merging surface-water hydrological processes. Differentiating and appropriately processing such ecohydrologically meaningful features remains a major technical terrain-processing challenge, particularly as highresolution spatial data are increasingly used to support modeling and geographic analysis needs. The objectives of this study were to delineate hierarchical wetland catchments and model their hydrologic connectivity using high-resolution lidar data and aerial imagery. The graph-theory-based contour tree method was used to delineate the hierarchical wetland catchments and characterize their geometric and topological properties. Potential hydrologic connectivity between wetlands and streams were simulated using the least-cost-path algorithm. The resulting flow network delineated potential flow paths connecting wetland depressions to each other or to the river network on scales finer than those available through the National Hydrography Dataset. The results demonstrated that our proposed framework is promising for improving overland flow simulation and hydrologic connectivity analysis.
Highlights
The prairie pothole region (PPR) of North America extends from the north-central United States (US) to southcentral Canada, encompassing a vast area of approximately 720 000 km2
We identified 15 784 inundation objects, which were compared against the National Wetlands Inventory (NWI) wetland polygons in our study area
The lidar intensity data were acquired in late October 2011, an extremely wet month according to the Palmer Hydrological Drought Index (Fig. 6)
Summary
The prairie pothole region (PPR) of North America extends from the north-central United States (US) to southcentral Canada, encompassing a vast area of approximately 720 000 km. The wetland depressions, commonly known as potholes, possess important hydrological and ecological functions, such as providing critical habitat for many migrating and breeding waterbirds (Minke, 2009), acting as nutrient sinks (Oslund et al, 2010), and storing surface water that can attenuate peak runoff during a flood event (Huang et al, 2011b). Most potholes have a water depth of less than 1 m with varying water permanency, ranging from temporary to permanent (Sloan, 1972). Due to their small size and shallow depth, these wetlands are highly sensitive to climate variability and are vulnerable to ecological, hydrological, and anthropogenic changes. In a report to the US Congress on the status of wetland resources, Dahl (1990) estimated that the con-
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