Surface-Water Connectivity Within a Coastal Lowland Riverine Landscape

Lowland riverine landscapes regularly flood and create complex spatial patterns of inundation that create surface-water connections between landscape patches that allow energy, matter, biota, and information to be exchanged. While the importance of surface-water connections has been recognized in the literature, there is no formal framework for quantifying these connections. The research presented here is guided by one main objective that aims to build towards the development of a framework for quantifying surface-water induced landscape connectivity within lowland riverine landscapes. Three specific objectives (SOs) were pursued in order to address this main objective. SO1 involves analyzing potential surface-water connections using a terrain-based approach and developing a methodology that relies on object-based analysis and graph/network theory to quantify connectivity. Results indicate that surface-water connectivity has a nonlinear relationship with river-stage and the connectivity is largely controlled by a hub-like structure. This is important because these hubs are ultimately what maintains river-floodplain process and fluvial habitat health. SO2 involves simulating surface-water inundation across the range of historical flows using a hydrodynamic model and analyzing the hub-like surface-water connectivity structure. Results indicate that the dynamic network created by surface-water connections between landscape patches has a roughly scale-free structure for several of the flow conditions considered. This is important because scale-free networks are known to have universal structure and function that can potentially be used to better understand interactions between elements of riverine landscape during flood events. SO3 involves developing sets of Stream Temperature, Intermittence, and Conductivity loggers (STICLs) that can monitor surface-water connectivity when deployed in the field. Results indicate that STICLs performed well at identifying intermittent inundation when they are deployed within portions of the riverine landscape that experience periodic inundation. Also, comparing STICL records with those from historical water quality samples allows the flooding mechanism for the inundating waters to be identified. This is important because STICLs provide a means for quantitatively monitoring surface-water connectivity in the field. These SOs collectively progress the development of a framework for quantifying surface-water connectivity of lowland riverine landscapes that ultimately allows for better management of these landscapes