DOW Nitrogen And Phosphorus Loads

The Kentucky SPARROW (SPAtially Referenced Regressions On Watershed Attributes) model estimates annual nitrogen and phosphorus loads (concentrations) for stream reaches throughout the state based on data from 40 monitored stations in Kentucky and Tennessee. Approximately 300 land use, municipal, and natural resource variables were evaluated in order to identify the significant contributing factors of nitrogen and phosphorus to our streams. The SPARROW model is a non-linear model that estimates the magnitude and significance of source and delivery variables for the downstream end of each stream segment (reach) based on measured data at monitored sites. The model then sums the nutrient load within each reach with those from the upstream reaches. The results presented here are from an adjusted model - this means that measured data for monitored reaches were included in the final model and used to adjust the model at each monitored reach and thereby improve the accuracy of the estimated nutrient concentrations. Consequently, the model is most accurate immediately downstream of a monitored reach. Conversely, the largest accumulated error is in reaches immediately upstream of a monitored reach. Data are reported with 90% lower and upper confidence bounds. For nitrogen, the sources were identified as agricultural land use (pasture plus cultivated land areas - NLCD 1992), atmospheric deposition of ammonium and nitrate (NADP), and wastewater (Hoos, 2007). Delivery of the atmospheric deposition is controlled by how water moves through the soil (soil permeability - STATSGO). In addition, there is depletion of stream nitrogen in the state's reservoirs (as estimated by the model). This nitrogen model has a yield R2 (accounting for the size of each drainage area) of 0.89. For phosphorus, the sources were identified as pasture (NLCD), soil phosphorus abundance (Karathanasis, 2006), and wastewater (Hoos, 2007). Delivery of phosphorus from pasture lands is related to a function of infiltration excess overland flow (Wolock, 2003). This phosphorus model has a yield R2 of 0.65. Questions? [e-mail] Download Link: https://ky.box.com/v/kymartian-nitrogen-phosporus