Striking a Balance
GIS-based User-friendly Model Helps Farmers Reduce Nutrient Pollution

Challenge
Rapid land development, combined with activities such as farming, fossil fuel consumption, and wastewater treatment have elevated nutrient levels in estuaries and coastal waters nationwide. According to the Pew Oceans Commission Report, more than 60 percent of U.S. coastal rivers and bays are degraded by nutrients from runoff. Because these water bodies vary enormously, coastal managers need site-specific tools to preserve water quality while at the same time striking a balance between competing uses of coastal resources.

Response
With a grant from CICEET, researchers from the University of New Hampshire and Applied Geosystems, LLC have developed a GIS-based toolkit to help land use decision makers modify farming practices to reduce nutrient loading. The DNDC (Denitrification Decomposition) model employs a graphical user interface to simulate nutrient processes in watersheds.

Developed to study greenhouse gas emissions, the DNDC has been successfully used to predict nutrient cycling in different environments. Until recently, however, it has only been available to the scientific community.

Researchers adapted the model for use in managing coastal watersheds by working with local managers, regulators, and farmers in California’s Elkhorn Slough watershed. Loaded with site-specific data, the DNDC program provides a map of the watershed that locates local farms. A mouse click on a property calls up information on climate conditions, soil properties, crop types and farming practices. A second click runs the nutrient cycling simulation. Parameters, such as fertilizer and irrigation, can be changed according to planned farming practices. Users can then compare simulation results to the current nutrient situation to reveal how changes in practice lead to changes in nitrogen leaching, carbon accumulation in the soil, crop yields, and other important variables.

Impact
Researchers held workshops in cooperation with the Elkhorn Slough National Estuarine Research Reserve to teach local researchers, regulators, managers and farmers how to use the model. The workshop helped stakeholders from a variety of technical backgrounds to better understand their role in nutrient cycling, and provided them with critical tools for optimizing farming practices and reducing environmental damage.

Though originally adapted for Elkhorn Slough, the DNDC model can be adapted for use in other watersheds. With a technology transfer grant from CICEET, the researchers currently are applying this model to Reserve sites in Ohio and Delaware.

The DNDC Model is online at www.dndc.sr.unh.edu

Learn More
Dr. Changsheng Li
University of New Hampshire
T: 603.862.1771
E: changsheng.li@unh.edu

Dr. William Salas
Applied GeoSolutions, LLC
T: 603.292.5747
E: wsalas@agsemail.com

Related Projects
In Situ Nutrient Monitor [Brief]

Automated Submarine Groundwater Discharge Analyzer [Bulletin]

Advanced Laser Fluorescence (ALF) Technology for Estuarine and Coastal Environmental Biomonitoring [Final Report]

Nutrient Pollutant Load and Source Estimation Model [Progress Report]

Measurement System for Localizing Groundwater Flows [Bulletin]

Continuous Imaging Flow Cytometer to Monitor Estuarine Microplankton [Bulletin]

A User Friendly Aid to Lower Nitrogen Loads to Estuaries [Bulletin]