Poster Presentation Society for Freshwater Science 2025 Annual Meeting

An interactive framework for integrated visualization and analysis of monitored and model-expected load reductions for nitrogen, phosphorus, and sediment (116757)

Qian Zhang 1 2 , Gary W. Shenk 3 , Gopal Bhatt 4 , Isabella Bertani 2
  1. Oak Ridge Institute for Science and Education Fellow c/o U.S. EPA Office of Research and Development, Washington, D.C.
  2. University of Maryland Center for Environmental Science / EPA Chesapeake Bay Program Office, Annapolis, MD, United States
  3. U.S. Geological Survey / EPA Chesapeake Bay Program Office, Annapolis, MD, United States
  4. Penn State University / EPA Chesapeake Bay Program Office, Annapolis, MD, United States

Reductions of nitrogen, phosphorus, and sediment loads have been the focus of watershed restoration in many regions for improving water quality, including the Chesapeake Bay. Watershed models and riverine monitoring data can provide important information on the progress of load reductions, but they do not always generate consistent interpretations. To better reconcile such inconsistencies between expectation (i.e., modeling estimates) and reality (i.e., monitoring information), a watershed-wide Total Maximum Daily Load (TMDL) indicator1 was developed for the Chesapeake Bay watershed to explicitly quantify the progress toward nutrient reduction goals. Results showed that since 1995 long-term progress has been made toward the TMDL planning targets for both nitrogen and phosphorus. The TMDL indicator framework can be transferred to other watersheds, where similar modeling and monitoring information exists, to gauge expectations on the trajectory and pace of the progress toward meeting restoration goals. In this regard, a new R Shiny app, named “Monitored and Expected Total Reduction Indicator for the Chesapeake (METRIC)2,” was developed to offer integrated visualization and analysis of monitoring and modeling data for the subwatersheds of the Chesapeake Bay. Although monitored and model-expected trends for individual subwatersheds are available from various agencies, there is a lack of integration, visualization, and direct comparison of these data sources. The METRIC app is designed to bridge this gap by making these complex data more accessible and user-friendly for managers and stakeholders. Currently, the METRIC app contains up-to-date information on nitrogen, phosphorus, and sediment at 83, 66, and 66 monitoring stations, respectively. These results were further synthesized to better understand the spatial patterns of the response classes (i.e., agreement between the expected and monitored trends) across the Bay watershed.

  1. Zhang, Q., G. Shenk, I. Bertani, and G. Bhatt, 2024. “Integrating monitoring and modeling information to develop an indicator of watershed progress toward nutrient reduction goals,” Ecological Indicators, 158:111357, doi: 10.1016/j.ecolind.2023.111357.
  2. Monitored and Expected Total Reduction Indicator for the Chesapeake (METRIC), https://wqs.chesapeakebay.net/metric/.