Characterizing hydrological connectivity and its impacts

Changes in the directional connectivity index (DCI) of sloughs (flow-ways) in the Everglades and forewarn of future loss in the aerial coverage of sloughs.

Changes in the directional connectivity index (DCI) of sloughs (flow-ways) in the Everglades and forewarn of future loss in the aerial coverage of sloughs. Click on the image to learn more.

Another ESDL theme related to the goal of understanding the linkage between landscape pattern and process is hydrological connectivity, or the spatial configuration of flow-ways. Of particular interest are environments with multiple flow paths and obstacles (e.g., islands, patches of vegetation). The physics of surface-water flow through such heterogeneous environments is generally more poorly understood than in heterogeneous aquifers, though many of the concepts and techniques are similar and transferable. In one ongoing project, we aim to quantify the spatial characteristics of flow through surface-water environments and understand how those characteristics influence flow velocities and reflect underlying processes. Early work has suggested that channel connectivity statistics distinguish between landscapes shaped by distinct sets of governing processes and hence may be diagnostic of the system’s dynamics. Changes in those connectivity characteristics can occur rapidly and precede major changes in the aerial distribution of landscape elements. Thus, connectivity statistics can also serve as an early-warning indicator of imminent landscape change. We are presently testing the hypothesis that directional connectivity statistics can distinguish between coastal landscapes that are subsiding and those that are aggrading, using tidal marshes along the Gulf Coast as a test case. Rapid quantification of connectivity statistics using remote sensing images could then be performed to pinpoint tidal marshes most in need of restoration or fortification.

Changes in the connectivity of the channel network structure on the Wax Lake Delta reflect its growth. The Wax Lake Delta is the only portion of the greater Mississippi River Delta complex that is growing over time.

Changes in the connectivity of the channel network structure on the Wax Lake Delta reflect its growth. The Wax Lake Delta is the only portion of the greater Mississippi River Delta complex that is growing over time.

An Alaskan river with remarkable channel-floodplain connectivity.

An Alaskan river with remarkable channel-floodplain connectivity.