Delineation of Pothole-Dominated Wetlands and Modeling of Their Threshold Behaviors

Time-invariant contributing area and full hydrologic connectivity are commonly assumed in traditional watershed delineation and modeling. In reality, however, contributing area of a depression-dominated prairie basin varies and undergoes a progressive evolution process that is characterized by unique threshold behaviors associated with the depression filling-spilling-merging-splitting-depleting dynamics. The research reported in this paper aims to precisely delineate prairie potholes and the associated wetlands, effectively characterize their dynamic hydrotopographic properties, and further quantify the resultant threshold behaviors and spatiotemporal variability in hydrologic connectivity. Delineation and modeling for a wetland site in the Prairie Pothole Region (PPR) highlighted the crucial role of topographic characteristics in the formation, evolution, and connectivity of prairie potholes. Particularly, the modeling tests for real rainfall demonstrated the significant impacts of complex rainfall patterns on the behavior of a PPR wetland system and the dynamic filling, spilling, merging, splitting, and depleting processes of potholes. The research reported in this paper provides an effective tool for dynamic pothole wetland delineation and hierarchical modeling, which can be potentially used for ecohydrologic modeling and assessment. (C) 2015 American Society of Civil Engineers.