Wide-ranging wetland-mediated water quality improvements revealed through watershed-scale simulations
Abstract
River basin-scale wetland restoration and construction is a potential nature-based solution (NBS) for water quality problems attributed to surplus nitrogen in agricultural landscapes. However, the magnitude of change that these practices will afford is uncertain, partly due to uncertainty in the plausible extent, location, and physical and functional characteristics of the yet-added wetlands. We used a process-based hydrologic model of the ~450,000 km2 Upper Mississippi River Basin (UMRB) to simulate a suite of over 2,400 wetland restoration and construction scenarios assuming varied placement strategies (i.e., targeted location vs. randomly placed) and physical and functional characteristics, including wetland catchment size, nitrogen-removal efficiency, tile-interception capacity, maximum storage, and seepage rates. These scenarios showed substantial range in the magnitude of projected nitrate load reduction that will result from any given areal extent of restored and constructed wetland. For example, if ~4,500 km2 of wetland (~1% of UMRB area) were restored or constructed, mean annual nitrate loads at the basin outlet were projected to decrease by between 3-42%. Higher magnitude load reductions necessitated rosier assumptions regarding the placement and characteristics of the yet-added wetlands, particularly with respect to wetland catchment size. Thus, we affirm that basin-scale wetland restoration and construction have the potential to provide strong water quality mediation effects. However, our findings contradict generalized claims of ubiquitous and substantial wetland mediated water quality improvements without consideration of controlling effects (e.g., location, wetland catchment size, etc.).
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H25N1272E