Development of a spatially distributed model for estimating nitrogen removal in forested riparian buffers

Claessens, LucRiparian buffers are a widely promoted best management practice for improving stream health and habitat benefits, including reducing instream nitrogen (N) loading. There is a large spatial variability in N removal within riparian buffers, which can largely be explained by buffer width and variations in subsurface water flux. Variable-width buffers are recommended, but there are no simple models to guide restoration efforts, and fixed-width buffers are the norm, also because they are easier to implement and regulate. The goal of our research is to improve riparian buffer restoration for reducing N loading. We developed a simple spatially explicit GIS model that estimates the N removal within riparian buffers and that can prioritize locations for variable-width buffers. The innovative part of our model is the spatially explicit prioritization scheme accounting for removal in both upslope and downslope areas. We tested the model on a watershed in the Mid-Atlantic Piedmont and we applied the model to compare fixed-width and variable-width buffers. Our results show that variable-width buffers require less area to reach N load reduction goals, compared to the fixed-width buffers. Our model will aid watershed managers to make well-informed decisions for prioritizing buffer placement and to maximize N removal and improve water quality.M.S.University of Delaware, Graduate Program in Water Science and Polic