Session Information
| Session | Poster Session | | Date | Monday (2008-04-07) | | Time | 5:00 PM - 7:00 PM | | Room | Grand Terrace |
Presentation Information
| Presenter | Molly Van Appledorn | | Title | A simulation comparing spatially-explicit riparian restoration strategies for water quality improvement within and among watersheds | | Affiliation | Utah State University | | Authors | Molly Van Appledorn, Matthew Baker | | Keywords | Landscape metrics, Non-point source pollution, Restoration, Riparian buffers, Watershed management | | Presentation Type | Poster | Abstract:
Restoration of riparian vegetation is a common strategy used to reduce non-point source pollution discharge to streams because of their potential to filter undesirable nutrients from upslope sources. However, current efforts often rely on “opportunistic” strategies for guiding streamside restoration activity. We use surface topography to explicitly link nutrient source areas to buffers along preferential flow pathways at the watershed scale, thus providing guidance for “targeted” restoration efforts. The purpose of this study is to compare cost-benefit implications of targeted and opportunistic restoration across an agricultural land-use gradient. We use Monte-Carlo simulations to model the effects of restoration location, extent, and relative success. In the targeted approach, we identify and rank unbuffered streamside reaches according to their ability to intercept nutrients within each watershed. Opportunistic restorations are modeled by random selection of candidate streamside locations. Riparian reaches selected by either approach are “restored” by modifying their nutrient retention capacity. Uncertainty regarding the effectiveness of each restoration is represented by assigning random values from a range of observed nutrient filtering scenarios. To distinguish effects of placement versus retention, we also simulate opportunistic restoration with maximum retention. We then compare the cost-benefit implications of a series of successive restorations in 9 watersheds representing a range of watershed land use and assess sensitivity to the extent of contiguous restoration effort.
We find that targeted restoration nearly always outperforms opportunistic approaches regardless of restoration extent. Placement of streamside restoration also appears more important than ensuring maximum nutrient retention in most watersheds. Further, targeted placement is more important when the extent of individual restoration reaches is smaller or when the distribution of nutrient source loading on flow pathways is uneven. Results from this study demonstrate the importance of incorporating assessment of source-stream connectivity into land-use planning. Such rapid assessment of watersheds for riparian management has the potential to be more cost-effective than current methods because it relies on a more precise conceptual framework to identify areas of greatest restoration potential. Without methods for linking nutrient sources to potential restoration sites, current restoration strategies are less likely to be effective within and among watersheds. |
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