Weighting Nitrogen and Phosphorus Export Coefficients to Represent Runoff and Trapping Likelihoods

Abstract:

Urbanization can alter nutrient cycles due to coupled interactions between society and the environment. This “urban biogeochemistry” both increases the amount of nutrients in stormwater runoff and reduces filtering opportunities before receiving waters. While the export coefficient (EC) and event mean concentration (EMC) are used frequently as scoping level models for nutrient loading, land cover EC and EMC values do not account for spatial variation in hydrological transport processes in the runoff contributing area and dispersal area (CADA). The representation of runoff and filtering likelihoods across landscapes has been developed to identify critical pollutant areas in landscapes. This research seeks to improve scoping level models to account for variation in biogeochemical cycles in urban environments. The CADA weighting framework has been used to represent spatial variation in P loading, and will be modified and enhanced to represent N loading via runoff and filtration likelihoods, including vegetative buffering and denitrification potential. The simplicity of this model will allow for first-order estimates of high N and P loading areas on the landscape using widely available datasets, and will help identify critical areas for management and pollutant reduction. Planners will then be able to adjust land uses within the model to assess the impact of spatial land cover on water quality.