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肯塔基州SPARROW（流域属性空间参考回归，SPAtially Referenced Regressions On Watershed Attributes）模型基于肯塔基州与田纳西州40个监测站点的实测数据，估算全州范围内各河段的年度氮、磷负荷（浓度）。 研究共评估了约300项土地利用、市政与自然资源变量，以识别导致溪流氮、磷污染的关键贡献因子。SPARROW模型属于非线性模型，可基于监测站点的实测数据，估算每个河段下游端点的污染源与输移变量的量级及显著性；随后模型会将该河段的营养盐负荷与上游河段的负荷进行累加。 本次发布的结果来自经过校准的模型：监测河段的实测数据已纳入最终模型，并用于校准各监测河段的模型参数，进而提升估算的营养盐浓度精度。因此，该模型在监测河段下游紧邻区域的估算精度最高；反之，监测河段上游紧邻区域的累积误差最大。本次发布的数据附带90%置信区间上下限。 针对氮污染，其来源被确定为农业用地（牧场与耕地总面积——基于1992年全国土地覆盖数据集（NLCD））、国家大气沉积监测项目（NADP）监测的大气铵态氮与硝态氮沉降，以及污水处理排放（Hoos, 2007）。大气沉降的输移过程受土壤水分运移条件控制（土壤渗透性——基于STATSGO土壤数据集）。此外，该州水库内存在溪流氮素的消减过程（由模型估算）。该氮模型考虑汇水面积的产量决定系数R²为0.89。 针对磷污染，其来源被确定为牧场用地（NLCD数据集）、土壤磷素丰度（Karathanasis, 2006）以及污水处理排放（Hoos, 2007）。牧场磷素的输移过程与超渗坡面流函数相关（Wolock, 2003）。该磷模型考虑汇水面积的产量决定系数R²为0.65。 如有疑问，请联系邮箱[e-mail]。下载链接：https://ky.box.com/v/kymartian-nitrogen-phosporus