Restoring stream – floodplain – aquifer connectivity in drained peatlands: Quantifying effects of restoration on groundwater storage regimes and hydrologic exchanges

Floodplains, wetlands, streams and riparian aquifers are critical water storage areas that are increasingly recognized for providing ecosystem services including flood attenuation, baseflow regulation, water quality improvement, carbon sequestration, ecosystem habitat and biodiversity. However, channel incision – from both intentional drainage efforts and as unintended consequence of anthropogenic activities – is a leading cause of stream and floodplain degradation due to cascading effects it has on riparian hydrology. Restoring the connectivity between streams, floodplains, and aquifers to enhance the natural exchange of surface water (SW) and groundwater (GW) is becoming more common, yet hydrologic outcomes are rarely monitored and highly uncertain, particularly related to plug-style restoration in humid-temperate climates and peatlands. In this project, we will evaluate how restoration of incised peatland channels alters the storage of groundwater and SW-GW exchanges. We will partner with the Necedah National Wildlife Refuge (NNWR) to develop an ecohydrologic observatory for monitoring of GW and SW response at two paired restored/unrestored reaches. We will characterize the a) hydrostratigraphy, b) storage properties, and c) transmissive properties of degraded and restored peatlands using ground-penetrating radar, laboratory drainage experiments performed on soil cores, and field hydraulic testing methods, respectively. We will use our network of SW and GW sensors to compare GW storage regimes and SW-GW interactions in restored and degraded stream-floodplain systems at both headwater and main-channel landscape positions. We will work closely with staff at the NNWR to determine whether this is an effective, nature-based approach to solving local water resource challenges related to GW drainage and SW flooding while also protecting regionally significant ecological resources. Project results will inform public investment in, and design of, restoration activities at the NNWR while also adding to the ongoing, national scientific debate regarding the role of plug-style restoration in impacting hydrologic exchange fluxes.