| Summary: | Traditional delineation and modeling methods do not consider the spatial arrangement and dynamic threshold control of surface depressions. Instead, full structural hydrologic connectivity, uniform well-connected drainage networks, and an invariant contributing area are often assumed. In reality, depressions play an important role in quantifying hydrologic connectivity and outlet discharge. Current literature lacks a preferred foundation and tools to identify and quantify hydrologic connectivity on depression-dominated landscapes. Therefore, the objectives of this dissertation research are to (1) develop a new procedure to analyze functional hydrologic connectivity related to surface topography, specifically in depression-dominated areas; (2) evaluate the impacts of the puddle-to-puddle (P2P) filling-spilling-merging processes and dynamic hydrologic connectivity on watershed outlet discharge; and (3) address the combined effect of topographic depressions and wetland functions on hydrologic connectivity and watershed outlet discharge. To accomplish these objectives, three studies are conducted where (1) a new procedure was developed for identifying and analyzing hydrologic connectivity in depression-dominated areas; (2) an improved HEC-HMS modeling framework was developed by incorporating a depression threshold control proxy; and (3) a new hydrologic categorization of wetlands was adapted for watershed-scale hydrologic modeling. The major findings from these studies include: (1) traditional delineation methods may fail to represent the realistic contributing area (CA), especially for depression-dominated surfaces; (2) the consideration of the P2P processes and dynamic contributing area is essential for hydrologic modeling of depression-dominated areas; and (3) different wetland types have unique characteristics of contributing area and depression storage that are not simulated in detail in most traditional models. The conclusions from this research also provides useful information for future studies relating to sediment and pollutant transport in depression-dominated regions, ecological interactions in wetlands, and anthropogenic effects on hydrologic processes. === North Dakota State University. Department of Civil and Environmental Engineering === North Dakota Water Resources Research Institute === National Science Foundation Established Program to Stimulate Competitive Research (NSF EPSCoR, Grant No. IIA-1355466)
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