CICEET Progress Report for the period 3/01/09 Through 8/31/09
Project Title: A Strategic Planning Tool for Targeted Buffer Restoration and Enhanced Coastal Stewardship
Principal Investigator(s): . Matthew Baker, Dr. Donald Weller, Dr. Thomas Jordan
Project Start Date: 9/01/06
Report Compiled by: Baker, Boomer
Contributing team members and their role in the project: Dr. Kathy Boomer, SERC (Research Associate), Molly Van Appledorn, USU/UMBC (Graduate Student), Dr. David Tarboton, USU (collaborator, programmer)
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For this reporting period we had several objectives including to (1) compare our results with other models for the Chesapeake Bay watershed, (2) continue analyses of alternate buffer delineation criteria, (3) compare results with a range of high-resolution. The last two objectives are an effort to assess uncertainty associated with the results of our tool using 30 m and 1:24000 scale geographic data (as recommended by our early-adopters). Considerable variation using data sources from different resolutions is an indication of greater uncertainty associated with the tool’s output.
We compared the management implications of our tool relative to the output of the USGS SPARROW model for the Chesapeake Bay Watershed. The SPARROW loading model is fit using the sum of all agricultural activity including confined animal feeding operations as well as cropland, whereas our predictions were based solely on the expected N concentrations from cropland. Nevertheless, proportions of cropland within each drainage unit account for ~63% of the variation in the SPARROW results. Predictions using the output from our riparian buffer tool and our empirical model suggest greater nutrient losses from Piedmont watersheds than those in the Delmarva peninsula (Figure 1). However, one variable not available to the SPARROW model is a differentiation between buffered and unbuffered cropland, which our tool identifies. Using the frequency of buffer gaps as a predictor, we were able to describe significant relationships with upper quantiles of SPARROW N-yield predictions. This preliminary finding suggests knowledge of buffer patterns may help explain further variation in patterns of N yield in the next generation of USGS modeling efforts.
An unanticipated complexity has emerged during the development of uncertainty estimates for our statistical models of N concentration. Because our models use an unusual approach for estimating buffer effects, confidence intervals for these predictions were not as straightforward as in other multiple regression analyses. This extended our timeline for manuscript submission somewhat, but we felt that detailed uncertainty estimates linked to our nutrient predictions would be an important addition to the contribution.
To assess uncertainty associated with map data resolution, we focused on a selected set of Coastal Plain study watersheds. Our first approach was to compare buffer metrics estimated from flow pathways developed from different resolutions of surface topography, including 1 to 2 m, 10m, and 30m grids. Preliminary analyses suggest that average buffer widths over the entire study area were similar among the different topographic data sets using the same land cover data and the same stream map. However, variation increased with the coarseness of the data when we compared buffer widths among individual sub-basins. As anticipated, these preliminary results suggest limitations of the tool for site-specific (i.e., field-scale) buffer characterizations using coarse-resolution geographic data.
We also compared different ways of mapping land cover classes that are likely to remove nutrients. The existing tool defines nutrient-removing land cover as forest or wetland land cover (National Land Cover Data) down-slope of a nutrient source that is contiguous with streams. We integrated high-resolution topography with land cover by mapping the nutrient-removing zone as forest/wetland land cover within 2 m elevation of surface water. Areas within this proximal elevation have the greatest potential for groundwater interactions with biological communities, thereby promoting denitrification and nitrogen removal.
We began by comparing the total amount of forest and wetland contiguous with streams to those that occur with 2m in elevation from stream channels (Figure 2). As expected, the area of contiguous forest/wetland was frequently greater than areas mapped as being topographically near streams. We also compared these proximal elevation forests and wetlands with buffer areas identified in other maps often utilized by land managers, such as state and federal wetland maps and hydric soil maps. The nutrient-removing zone mapped by integrating land cover and topography did include wetlands and hydric soil zones from wetland and soil maps, and also included additional area that might have a strong likelihood for intercepting nutrients (Figure 3). However, none of these comparisons examined nutrient-removing zones that were below source areas. Thus, our next investigation will compare how mapped buffer areas down-slope of nutrient sources change when they are defined by federal wetland/hydric soil maps or constrained to be within 2m of streams.
We have continued developing methods for summarizing the cumulative extent and nutrient retention capacity of riparian buffers along entire stream networks. We are relating riparian width and local riparian topographic gradients to local contributing area and stream network location. We hope to better explain the observed variation in stream nitrate discharge among streams within the Chesapeake Bay watershed.
B. Please describe knowledge dissemination activities during this reporting period.
We presented our tools and analytical results to a broad science and management audience through two talks at the Chesapeake Ecosystem Based Management conference in March as part of a session showcasing CICEET funded work. We also presented two talks at the US-Chapter of the International Association of Landscape Ecology in April, the North American Benthological Society in May, and the Ecological Society of America meetings in August.
Baker, M.E., D.E. Weller, and T.E. Jordan 2009 Strategic tools for targeted riparian buffer restoration: developing priorities and reasonable expectations for nutrient reductions. CRC Regional Conference. Ecosystem Based Management: the Chesapeake and Other Systems. March 22-25, 2009.
Weller, D. E., M. E. Baker, and T. E. Jordan. 2009. Riparian buffer effects on discharges of watershed nitrate discharges: New models and management implications. 2009 CRC Regional Conference. Ecosystem Based Management: the Chesapeake and Other Systems. March 22-25, 2009.
Van Appledorn, M. and M.E. Baker 2009 Using Estimates of Nutrient Retention to Inform Riparian Buffer Metrics Annual meeting of the International Association of Landscape Ecology: US regional chapter. April 13-17, Snowbird, Utah.
Weller, D.E., M.E. Baker and T.E. Jordan 2009 New Spatial and Statistical Approaches Quantify the Effects of Riparian Buffers on Nitrate Discharges From Whole Catchments Annual meeting of the International Association of Landscape Ecology: US regional chapter. April 13-17, Snowbird, Utah.
Boomer, K. B., D. E. Weller, T. E. Jordan, and M. E. Baker. 2009. Characterizing riparian and floodplain functions with high-resolution topographic data. 94th Annual Meeting of the Ecological Society of America, Albuquerque, NM. August 3-7, 2009.
Weller, D.E., Baker, M.E., and Jordan, T.E. 2009. Riparian buffer effects on whole watershed nitrate discharges: new models and management implications. Invited talk. May 6, 2009. Univ. of Maryland Center for Environmental Studies, Chesapeake Biological Laboratory, Solomons, MD, USA.
Van Appledorn, M. and M.E. Baker 2009 Using estimates of nutrient retention to inform riparian buffer metrics for water quality improvement Annual meeting of the North American Benthological Society, May 16-23, Grand Rapids, Michigan
Baker, M.E., D.E. Weller, and T.E. Jordan 2009 Riparian buffer effects on discharges of watershed nitrate discharges: New models and management implications Annual meeting of the North American Benthological Society, May 16-23, Grand Rapids, Michigan
In addition to these professional presentations, Baker has given invited seminars to key personnel within several federal agencies including US-EPA (webinar to landscape ecology branch and ecosystem services personnel), USGS (Biological Resources Division and SPARROW modeling group). Also, he presented the tools to TNC Chesapeake Regional office and both Maryland and Delaware state conservation staff. In each case, seminars have resulted in new users of the tool.
C. Have the results/data gathered during this reporting period indicated that a change to your original approach is necessary? If so, who was involved in the decision-making process? Please explain.
Our results to date suggest that ours is a valid and appropriate approach for addressing the need to better understand riparian effects. However, our work also suggests potential and incremental improvements to our tool are possible and even necessary to meet the many different expectations end-users have for what such tools can and should accomplish.
D. Please describe collaboration activities with target stakeholders during this period. Has interaction with stakeholders during this period brought about any changes to the project? Have the stakeholders confirmed the relevance of the technology or approach you are working on?
Most of our interactions with stakeholders during this reporting period have been quite informative and rewarding. Nearly all of our collaborators have their own vision for where they want to take the functionality of our tool, and we view their desire to build on what we have developed thus far as an indication of the success of our project.
E. Please describe technical and non-technical objectives for the next reporting period and outline your work plan to meet identified objectives.
We will extend our high-resolution analyses from the Coastal Plain to clusters of watersheds in other physiographic provinces of the Chesapeake Bay watershed. We also will examine the effects of the flow-routing algorithm (uni- vs. multi directional flow) on estimates of nitrogen removal by riparian buffers in selected watersheds.
We will continue to develop relationships with potential end users and provide them with the tool at their request.
We will work to publish some of our findings thus far, to broaden the impact of our results.
We will continue to add incremental improvements to the software tools for ArcGIS, including terrain-based definitions of “riparian” to better identify likely zones of nitrogen removal. We will also develop the capacity to "parellelize" the multi-directional flow algorithms to enable processing of vast areas of landscape all at once from a desktop machine (and not a super computer). This could be a substantial, general advance in multidirectional flow modeling for many forms of environmental modeling related to estuarine management.
F. Please describe any activities, accomplishments, or obstacles not addressed in other sections of this report that you feel are important for CICEET to know about.
Our works has spawned several new opportunities for collaboration and application of our tool in a landscape optimization framework. Some of the technical insight we gained from this work has also led to improvements in other water quality modeling frameworks. Much of the work has involved direct employment and education of underrepresented groups in environmental science and engineering. All of these might be considered "broader impacts" of CICEET support.