Billions of dollars are spent annually on stream restoration, but assessments of restoration impacts on in-channel ecosystems are rare, and investigations into hyporheic impacts are practically absent. Most restoration projects aim to improve degraded stream structure and function by manipulating channel morphology to replicate pre-degradation conditions. The complex interactions of surface and subsurface flow in the hyporheic zone associated with restoration structures may play an important role in the ecological recovery of these projects, particularly with respect to water quality and aquatic habitat. The overall objective of this project is to assess 1) the degree to which in-stream restoration projects mimic natural bedform processes by inducing rapid hyporheic interaction, and 2) the resultant impacts on heterogeneity of associated physical, chemical, thermal and biological patterns in streambeds. Restoration projects will be assessed in the field relative to degraded sites, where restoration projects have not been implemented, and reference sites, which represent an ideal condition and on which the restoration design was based. Computational modeling will guide site instrumentation, investigate hydraulic drivers of water flux, and scale the results to larger reach lengths. The questions we will address include: 1. Does an engineered stream restoration design serve as an analog of natural stream features that drive hydraulics and enhance water flux through the streambed? Are streambed fluxes comparable in magnitude and spatial heterogeneity to those found at reference reaches that serve as the basis for the engineering design? 2. Does water flux through the streambed around restoration structures generate a mosaic of redox conditions and thermal patterns that are more spatially heterogeneous and span a greater range than those found at non-restored sites? Are these spatial patterns comparable to the spatial patterns found at reference sites? 3. Does the mosaic of hydrologic, redox and thermal conditions diversify habitat for hyporheic macroinvertebrates and result in greater hyporheic invertebrate taxonomic richness and community patchiness, compared to non-restored sites?
The proposed work addresses current gaps in our knowledge of how instream restoration projects impact hyporheic exchange and improve hyporheic function, particularly in terms of water quality and habitat restoration. The results of our work will inform future restoration design and demonstrate that restoration design considerations should include the vertical component, not simply channel form and process. Through exploratory computational modeling of hyporheic fluxes around proposed restoration structures, we can examine whether restoration designs maximize physicochemical and biological diversity in the stream system, restoring ecological function. The project team will actively engage practitioners through participation in training and workshops on stream restoration held annually throughout Upstate New York. Our work will also establish post-restoration monitoring at projects implemented by state and federal agencies. The proposed project explicitly incorporates the active participation of graduate and undergraduate students in research. Women and traditionally underrepresented minorities will be actively recruited for graduate student participation. Three undergraduate students will be recruited to complete independent research projects related to the modeling and biotic components of this project. We will activelyengage a broader audience of graduate and undergraduate students in this research program by incorporating educational experiences that are directly linked to active research into the curriculum of four courses at Syracuse University and SUNY ESF.
