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Intermittent Surface Water Connectivity: Fill and Spill Vs. Fill and Merge Dynamics.
Citation:
Leibowitz, Scott G, D. Mushet, AND W. Newton. Intermittent Surface Water Connectivity: Fill and Spill Vs. Fill and Merge Dynamics. 2017 AWRA Spring Specialty Conference on Aquatic System Connectivity, Snowbird, UT, May 01 - 03, 2017.
Impact/Purpose:
Under the Safe and Sustainable Water Resources National Program, work is being done to quantify spatial and temporal variation in wetland connectivity in three regions, including the Prairie Pothole Region. In this study, we examine intermittent surface water connectivity between water bodies, which can influence aquatic systems through movement of chemical and biotic constituents via water flow. In particular, we identify two separate types of surface water connectivity – fill and spill vs. fill and merge – and examine the effects they have on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. This work is a supplemental study under SSWR 3.01G, and will contribute to other studies being conducted under an ongoing Interagency Agreement with the US Geological Survey.
Description:
Intermittent surface connectivity can influence aquatic systems, since chemical and biotic movements are often associated with water flow. Although often referred to as fill and spill, wetlands also fill and merge. We examined the effects of these connection types on water levels, ion concentrations, and biotic communities of eight prairie pothole wetlands between 1979 and 2015. Fill and spill caused pulsed surface water connections that were limited to periods following spring snow melt. In contrast, two wetlands connected through fill and merge experienced a nearly continuous, 20-year surface water connection and had completely coincident water levels. Fill and spill led to minimal convergence in dissolved ions and macroinvertebrate composition, while these constituents converged under fill and merge. The primary factor determining difference in responses was duration of the surface water connection between wetland pairs. Our findings suggest that investigations into the effects of intermittent surface water connections should not consider these connections generically, but need to address the specific types of connections. In particular, fill and spill promotes external water exports while fill and merge favors internal storage. The behaviors of such intermittent connections will likely be accentuated under a future with more frequent and severe climate extremes.