Flooding and Surface Connectivity of Taxodium‐Nyssa Stands in a Southern Floodplain Forest Ecosystem

Abstract

An understanding of the factors controlling the permanent and episodic links between the main stem of a river and the ecosystems of its alluvial floodplain is necessary for evaluating the influence of modern river processes on floodplain ecology and habitat diversity and for the successful implementation of flow regimes that meet human needs for water in a manner that sustains the ecological integrity of affected systems. In this study, we examined relationships between river hydrology and lateral hydrological connectivity, which is crucial to directing fluxes of water, material, and organisms into and across a floodplain. We did so by translating measures of river discharge for the Congaree River into high resolution maps of flood conditions for the floodplain at Congaree National Park using a 2D flood inundation model. Utilizing a graph network approach, we then analyzed the connectivity of a key wetland ecosystem, Taxodium‐Nyssa forested swamps, to the main stem river and to each other under different flows. Our results underscore that floodplain connectivity is initiated at sub‐bankfull discharges and does not depend on levee overtopping, while also clarifying that various sources of connectivity are triggered at different flow levels in specific reaches. Further, our findings demonstrate the sensitive and non‐linear response of floodplain connectivity to river flows and provide useful information to facilitate the management of flood processes in the Congaree River watershed. Copyright © 2014 John Wiley & Sons, Ltd.

River‐valley morphology, basin size, and flow‐event magnitude interact to produce wide variation in flooding dynamics

“…For example, 2D hydrodynamic models have been used to quantify hydrologic connectivity patterns among forest patches for the purposes of environmental flow regulation (Kupfer et al. , Meitzen and Kupfer ) and to reveal hydrologic and hydraulic drivers of floodplain sedimentation dynamics that would have been difficult to ascertain by other approaches (Kaase and Kupfer ).…”

Hydrodynamic Modeling Improves Green River Reconnection with Floodplain Wetlands for Endangered Fish Species Recovery

“…Kupfer et al. () found a nonlinear response of floodplain connectivity with river flows in a bottomland forested floodplain in South Carolina that started at sub‐bankfull discharges initially independent of levee overtopping. Various sources of connectivity were triggered at different flow levels in different areas, and initial flooding links some wetlands to each other over short distances through distributory channels and potential subsurface flow (Kupfer and Meitzen ; Kupfer et al.…”

“…Various sources of connectivity were triggered at different flow levels in different areas, and initial flooding links some wetlands to each other over short distances through distributory channels and potential subsurface flow (Kupfer and Meitzen ; Kupfer et al. ).…”

“…For example, Kupfer and Meitzen () and Kupfer et al. () used the 2D flow model, TUFLOW, to simulate flood inundation and hydrological connectivity across the Congaree River floodplain in Congaree National Park, South Carolina. MIKE‐21 has been used to model wetland connectivity during overbank flooding in a tropical floodplain in North Queensland, Australia (Karim et al.…”

Graph theory in the geosciences

“…floodplain connectivity of alluvial wetlands was found to be non-linear and initiated at sub-banktop flows via a graph analysis by Kupfer et al (2014).…”