Estimating restorable wetland water storage at landscape scales

Abstract

Globally, hydrologic modifications such as ditching and subsurface drainage have significantly reduced wetland water storage capacity (i.e., volume of surface water a wetland can retain) and consequent wetland functions. While wetland area has been well documented across many landscapes and used to guide restoration efforts, few studies have directly quantified the associated wetland storage capacity. Here, we present a novel raster-based approach to quantify both contemporary and potential (i.e., restorable) storage capacities of individual depressional basins across landscapes. We demonstrate the utility of this method by applying it to the Delmarva Peninsula, a region punctuated by both depressional wetlands and drainage ditches. Across the entire peninsula, we estimated that restoration (i.e., plugging ditches) could increase storage capacity by 80%. Focusing on an individual watershed, we found that over 59% of restorable storage capacity occurs within 20 m of the drainage network, and that 93% occurs within 1 m elevation of the drainage network. Our demonstration highlights widespread ditching in this landscape, spatial patterns of both contemporary and potential storage capacities, and clear opportunities for hydrologic restoration. In Delmarva and more broadly, our novel approach can inform targeted landscape-scale conservation and restoration efforts to optimize hydrologically mediated wetland functions.

Runoff Storage Potential of Drained Upland Depressions on the Des Moines Lobe of Iowa

“…Recent variants of this approach have also been used by Kessler and Gupta (), and by Jones et al. (), but, in contrast to these studies, we expand upon this type of analysis to also include estimation of runoff storage indices ( R s ) using estimates of 24‐h rainfall amounts likely to occur within this region at different frequencies. The approach taken in this study is similar in some respects to the methods used by Ludden et al.…”

“…The approach used in the SDMT to identify depressional basins and derive their morphologies is similar, but not identical, to methods employed for the derivation of depressional storage capacity by Jones et al. ().…”

“…Jones et al. () applied an algorithm, similar to the one presented in this study, to estimate the storage volumes of potentially restorable drained depressions within the Del Marva Peninsula, forming the eastern boundary of the Chesapeake Bay, using 3 m LiDAR‐derived DEMs. Additional examples of the use of LiDAR‐derived elevation data for delineating depressional wetlands within the PPR include Huang et al.…”

Landscape metrics as predictors of hydrologic connectivity between Coastal Plain forested wetlands and streams

“…Across the Peninsula, approximately 70% of Delmarva bays have been hydrologically altered for agriculture (Fenstermacher, Rabenhorst, Lang, McCarty, & Needelman, ), typically by ditch drainage, which increases transport of water and contaminants (e.g., nitrogen) to streams and the Chesapeake Bay (Denver et al, ). In a recent study of potential surface water storage, a key landscape function through which Delmarva bays retain and process constituents of runoff, Jones et al () estimated that plugging of ditches would increase natural water storage capacity by 76% across the entire Delmarva Peninsula, and 250% in a single subcatchment, roughly equivalent to a HUC12, that has a high density of Delmarva bays. Full restoration of landscape functions of Delmarva bay wetlands is dependent upon a better understanding of the factors controlling their hydrologic connectivity to streams (McDonough et al, ).…”

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

“…; Jones et al. ). In recognition of this loss, NFWs have been the focus of policy debates at both state and federal levels, and central to this debate is uncertainty associated with their hydrologic connectivity to downstream waters and associated influences to the physical, chemical, and biological integrity of such waters (e.g., “significant nexus”; see Alexander ; Creed et al.…”