The Role of Lake Expansion in Altering the Wetland Landscape of the Prairie Pothole Region, United States

Abstract

Interannual variation in lake extent is well documented in the Prairie Pothole Region, but the role of surfacewater expansion, including lake expansion, in merging with and subsuming wetlands across the landscape has been minimally considered. We examined how the expansion of surface-water extent, in particular, the expansion of lakes across parts of the Prairie Pothole Region can alter landscape-level hydrologic connectivity among substantial numbers of previously surficially disconnected wetlands. Temporally static wetland, lake, and stream datasets were fused with temporally varying Landsat-derived surface-water extent maps to quantify changes in surface-water connectivity. Under deluge conditions, lakes were found to create significantly larger complexes of surficially-connected wetlands relative to non-lake surface-water connections (e.g., only wetlands or wetlands and streams). Analysis of three specific lakes showed that lakes can merge with and subsume wetlands located kilometers to tens of kilometers from the National Wetland Inventory defined lake perimeter. As climate across the Prairie Pothole Region is highly variable, understanding historic patterns of surface-water expansion and contraction under drought-to-deluge conditions will be integral to predicting future effects of climate change on wetland function, loss and influence on other aquatic systems, including downstream waters.

Patterns and drivers for wetland connections in the Prairie Pothole Region, United States

“…Both small (2-10) and large ([100) wetland clusters (or complexes of surficially connected or consolidated wetlands) were common across the study area. The consolidation of wetlands was particularly common around lake features, many of which occur in open, flat basins in which excess water can result in 100% to almost 600% increases in surface-water extent (Vanderhoof and Alexander 2015) (Fig. 6).…”

“…Although many factors may influence individual wetland hydrology (e.g., water retention capacity, topography, flow characteristics), simple parameters such as distance can be appealing to decision-makers, who need ''bright line boundaries'' between policy categories (Alexander 2015). It is therefore worthwhile to consider correlations with easily-measured structural parameters.…”

Modeling Connectivity of Non‐floodplain Wetlands: Insights, Approaches, and Recommendations

“…Empirical investigations included temporal measurements of surface‐water hydrologic fluxes in a wetland complex (Leibowitz et al. ), remotely sensed imagery to determine spatial and temporal patterns of wetland inundation (Vanderhoof and Alexander ; Vanderhoof et al. ), and water isotope analysis to examine potential contribution of wetlands to streamflow (Brooks et al.…”

Midcontinent Prairie-Pothole Wetlands and Climate Change: an Introduction to the Supplemental Issue

“…Recent changes in climate extremes combined with hydrologic alteration of landscapes within the region have resulted in prairie-pothole lakes greatly expanding in surface area and subsuming many nearby, and some not-so-nearby, wetlands. Vanderhoof and Alexander (2016) explore how lake expansion has influenced wetlands across the landscape of the PPR, in some cases increasing connectivity among aquatic systems, while in others, contributing to the loss of wetland functions when wetlands are entirely subsumed by an expanded lake. At a more localized scale, Leibowitz et al (2016) identify differences between fill-andspill versus fill-and-merge hydrologic processes and differing effects of each on the water chemistry and biotic communities of prairie-pothole wetlands.…”