CICEET Progress Report for the period 3/01/09 Through 8/31/09
Project Title: Applying multiple models to inform watershed management and land use planning in a coastal community.
Principal Investigator(s): Kathy Boomer
Project Start Date: September 1, 2007
Report Compiled By: Kathy Boomer
Contributing team members and their role in the project: Yong Li (GWLF and HSPF model applications); Latif Kalin (SWAT and L-THIA model applications); Don Weller (project implementation and facilitation)
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Appendices
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Objectives
Our objectives for this reporting period included 1) applying the calibrated models to the Queenstown Planning Area to predict how alternative growth scenarios and climate change might affect nutrient discharges; and 2) integrating results from the models (GWLF, SWAT, HSPF, and L-THIA) to develop model-averaged predictions. To date, we have completed the GWLF, SWAT, and L-THIA Queenstown applications, and we obtained model results from the Chesapeake Bay Program’s HSPF application. We also derived annual average discharge estimates using Maryland’s Non-Point Source Assessment Spreadsheet. The spreadsheet was developed specifically to estimate changes in non-point source loads associated with alternative development scenarios so that local municipalities can complete a state-mandated Water Resource Element. In addition, we have begun organizing output from our other models in a format consistent with Maryland’s Water Resource Element requirement so that our results can be incorporated directly into the Town of Queenstown’s Comprehensive Plan. Below, we report progress in each modeling effort and highlight summary results obtained during the current reporting period. Appendix A includes background data used for the model applications that is helpful in interpreting the results. Appendices B through E include results from the individual modeling efforts.
Generalized Watershed Loading Function (GWLF): During the current reporting period, we completed the GWLF-based climate change analysis and a preliminary assessment of land use change effects on nutrient discharges from the Queenstown Planning Area. We applied the GWLF using weather data from 1995 to 2004. Water flow varied little in response to land use change (range: 34.6 to 37.4 cm per ha per year). Annual TN and TP discharge estimates were closely related to predicted stream discharge, but the magnitude of changes associated with alternate growth scenarios were greater. For all three growth scenarios, preliminary results suggest that the current incorporated municipality (QT01) has the highest total N yield (95 to 135 kg N per ha per year) and TP yield (13 to 18 kg P per ha per year). Decreased cropland acreages in the future growth scenarios resulted in lower TN yields across the study area, but had little effect on TP discharge. Overall, the county-based, distributed (“buildout”) land use scenario produced the highest TN and TP discharges, while the consolidated growth option with low impact farming practices produced the lowest TN and TP discharges. Changes in land cover conditions reduced TN loads by less than 20% and TP by less than 30%, except for QT07 where TN loads were reduced by 75%. . Climatic changes in precipitation changed predicted TN and TP loads by up to 25%.
SWAT MODEL: During the current reporting period, the SWAT model calibration and validation were finalized, and climate change effects were evaluated for the Queenstown Planning area. The calibration and validation analyses showed that stream flow predictions were more reliable than estimated total nitrogen and phosphorus loads. The SWAT model performed similarly among the three calibration watersheds (SERC-304, SERC-310, and USGS-Greensboro) and the three verification watersheds (SERC-305, SERC-306, and USGS-Ruthsburg). SWAT predictions based on the CCC climate change scenario indicate a general decrease in stream flow, total nitrogen discharge, and sediment discharge over the next 100+ years (compared to current conditions: -25 m3 flow per hectare per year, -10 kg TN per hectare per year, and -20 kg sediment per hectare per year); whereas SWAT predictions based on the Hadley2 climate change model indicate increased flow, total nitrogen, and sediment (compared to current conditions: +10 m3 flow per hectare per year, +30 kg TN per hectare per year, and +10 kg sediment per hectare per year). TP discharge decreased compared to current conditions,(-1 kg P hectare/year) under both climate change scenarios. To evaluate how strongly calibration influences the predictions and data interpretations, we compared estimates of flow and nutrient discharge derived from calibrated and uncalibrated SWAT model applications. Preliminary results suggest that both applications provided similarly reliable flow and TN estimates, but TP loads estimated from the calibrated model matched the observed data more consistently.
Annual average TN and TP loads were generated for the Queenstown Planning area under current conditions (i.e., based on weather data from 1995 through 2004) along with annual loads for wet and dry years. Within the Queenstown Planning Area, the SWAT application indicated that the current municipality (QT01) and headwater areas (QT05, QT06, and QT08) had the highest TN and TP yields. Predicted nutrient loading rates during wet years were almost twice as much as those predicted under dry conditions.
L-THIA: We have progressed with applying the L-THIA model for the study area. Current efforts focus on the calibration/verification watersheds, but we will also apply the model to the Queenstown Planning Area. The annual average predictions will provide useful comparisons to Maryland’s non-point source assessment spreadsheet.
Maryland’s Non-point Source Assessment Spreadsheet: Annual average TN and TP loads were estimated for the Queenstown modeling segments using the Maryland State Department of Planning Nutrient Analysis Spreadsheet. The loading analysis uses unit area loading rates derived from the Chesapeake Bay Program’s Watershed Model (Phase 4.3). The unit-area loading rates vary by land cover/land use category. The model predicts substantially higher loads associated with the county planning department’s distributed growth scenario, especially in the Chester River/Queenstown Harbor watershed (segments QT01, QT02, QT04, QT11, and QT14). The higher loads come largely from septic systems. Nutrient loads to the Wye River, however, are lowest with the distributed growth option because of reduced cropland area, which does not occur under the consolidated growth options. The spreadsheet does not use weather data; therefore climate change effects cannot be evaluated.
Additional Summary output tables and figure. Please see attached appendices.
Please describe knowledge dissemination activities during this reporting period.
Throughout the reporting period, we regularly attended meetings with the Queenstown Planning Commission. Our results were incorporated in a successful grant proposal to update storm water and zoning ordinances. In addition, we collaborated with the town planners to prepare a presentation for the Ecosystem Based Management Conference.
Presentations:
Boomer, K.B., P. Faux, B. Galloway, L. Kalin, X. Li, and D. Weller. Promoting Ecosystem-Based Management in a Chesapeake Bay Coastal Community. 2009 Chesapeake Research Consortium Regional Conference. Baltimore, MD. March 22-25, 2009.
Kam, J., K. Boomer, and D. Weller. Application of the SWAT model to evaluate effects of land use change on stream discharge in Spring Creek, PA. 2009 Chesapeake Research Consortium Regional Conference. Baltimore, MD. March 22-25, 2009.
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.
None to report.
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?
Progress in developing a Comprehensive Plan for the Queenstown study area has been hampered by residents concerned about the currently-selected future growth plan. Interactions among the stakeholders have not altered our project goals, but have increased interest in our efforts and results.
Please describe technical and non-technical objectives for the next reporting period and outline your work plan to meet identified objectives.
Objectives for the next reporting period include:
- Complete the SWAT-based analysis of alternative land use scenarios for the Queenstown Planning area
- Finalize GWLF-based discharge predictions derived from alternative land use/land cover scenarios.
- Downscale results from the Chesapeake Bay Program’s HSPF Phase 4 and 5 applications to predict effects of land cover/land use change in the Queenstown Planning Area.
- Develop model-averaged predictions for the entire study area.
- Draft three manuscripts. The first will focus on our experience with linking science and management and will likely target a Land Use Planning publication. The second manuscript will focus on comparing results from the calibration and verification efforts among the different models. The third paper will compare the relative impacts of land use and climate change on surface water quality across a municipal planning area. Ultimately, we envision a fourth paper evaluating the utility of weighted model averaging for improving watershed predictions.
- Continue meeting regularly with the Queenstown Planning Area and other stakeholders in the planning area.
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.
Early in the project we proposed to expand the scope of our study area to include a large portion of Queen Anne’s County as outreach to County Planning Department. Since then, it has been challenging to engage the County’s interest in our efforts. More importantly, evaluating land cover effects on individual watershed segments has required more time and effort than we anticipated. Therefore, we are planning to limit the number of application segments to those shown in Appendix A, Figures 1 and 2) Focusing on the Queenstown Planning Area will fulfill the needs of our collaborators, including the local government and allow us to complete critical work products more quickly.