Spatial Variability in Nutrient Transport by HUC 8, State, and Subbasin Based on Mississippi/Atchafalaya River Basin SPARROW Models

摘要: Nitrogen (N) and phosphorus (P) loading from the Mississippi/Atchafalaya River Basin (MARB) has been linked to hypoxia in Gulf of Mexico. With geospatial datasets for 2002, including inputs wastewater treatment plants (WWTPs), monitored loads throughout MARB, SPAtially Referenced Regression On Watershed attributes (SPARROW) watershed models were constructed specifically which reduced simulation errors previous models. Based on these models, N loads/yields highest central part (centered over Iowa Indiana) MARB (Corn Belt), P yields scattered MARB. Spatial differences studies resulted different descriptions dominant sources (N are with crop-oriented agriculture crop animal major WWTPs) downstream transport. Delivered SPARROW used rank subbasins, states, eight-digit Hydrologic Unit Code basins (HUC8s) by contributions then rankings compared those other studies. Changes delivered result an average absolute change 1.3 1.9 places state ranking 41 69 HUC8 made national-scale This information may help managers decide where efforts could have largest effects (highest ranked areas) thus reduce