Linking Dynamic Connectivity and Hydrological Response
Author | : Molly R. Cain |
Publisher | : |
Total Pages | : 0 |
Release | : 2022 |
Genre | : Groundwater flow |
ISBN | : |
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The dynamic connection and disconnection of water storages in landscapes is a key control on water and solute transport and transformation. However, the processes that control how and when landscapes connect to their streams are complex. Hydrologic connectivity, which often exhibits transient and threshold behavior, depends upon antecedent wetness and hydrologic forcing conditions which modify water fluxes through space and time. Further, the dominant controls on connectivity vary with landscape structure (i.e., natural topography, topology, and geology, as well as human modifications to drainage structure). Characterizations of hydrologic connectivity as a function of antecedent conditions, hydrologic forcing conditions, and landscape structure are needed to accurately predict hydrologic and solute responses as well as to assess their influence on associated ecosystem services.In this body of work, I advance understanding of how dynamic hydrologic connectivity controls hydrologic response across a range of landscapes. I achieve this using a combination of field observations and numerical modeling. The first study explores how representing moisture-dependent, pore-scale hydrologic connectivity-a process called ecohydrologic separation-in a catchment-scale hydrologic model alters interpretations of stores, fluxes, and residence times of water and solutes. The following two chapters assess hydrologic connectivity dynamics in low-gradient landscapes of the Midwestern U.S. The second study explores how antecedent conditions control thresholds of runoff generation and nitrate export in tile-drained agricultural fields using field observations and coupled water and nitrogen cycle simulations. The final study characterizes the spatial and temporal variability of flooding dynamics within topographic features of a minimally human-disturbed floodplain system, highlighting the role of floodplain channels in enhancing river-floodplain connectivity.Overall, this research details conceptualizations of hydrologic connectivity in landscapes not commonly considered in current connectivity frameworks (low-gradient floodplains and intensively managed agricultural landscapes) and presents a novel representation of a moisture-dependent, hydrologic connectivity process and its ecological implications in a highly studied landscape (forested hillslopes).