SENSEmap-USGLB: Nitrogen and Phosphorus Inputs

SENSEmap-USGLB, the Spatially Explicit Nutrient Source Estimate map for the United States Great Lakes Basin, estimates inputs to the landscape from seven sources of nitrogen and six sources of phosphorus at 30 meter resolution for an average year during the 2008-2015 period. SENSEmap uses statistical and machine learning methods to estimate nutrient inputs using remotely sensed data, government records, and literature values. The sources include atmospheric deposition, chemical agricultural fertilizer, chemical nonagricultural fertilizer, manure, septic tanks, nitrogen fixation from legumes, and point sources. This resource includes 30 meter maps of each source along with corresponding watershed summaries at the Hydrologic Unit Code 12 (HUC12) and HUC8 levels, as defined in the USGS 2014 Watershed Boundary Dataset. Watershed summaries include total nitrogen and phosphorus in kg/yr, area normalized watershed inputs in kg/ha/yr, percent contribution of each source individually, and the percent contributions of combined agricultural sources and non-agricultural sources. Single-year per crop estimates of total nitrogen fixation inputs are also included. The values provided represent an average nutrient input in kg/ha/yr over the 2008-2015 period, generated from a single model realization. SENSEmap may be used to quantify nutrient inputs within nutrient budgets, process-based models, and water quality health indicators. SENSEmap estimates are not loads to groundwater, streams, or lakes and do not include nutrient exports due to harvest, denitrification, or other processes. SENSEmap is a regional-scale estimate, produced at fine resolution, and includes stochastic processes for certain inputs. As such, it should not be used for field level assessments, or where precise knowledge of local inputs is of key concern. SENSEmap-USGLB is described in full detail in the manuscript and supporting information of Hamlin et al.'s (2020) “Spatially Explicit Nutrient Source Estimate Map (SENSEmap): Quantifying Landscape Nutrient Inputs With Spatially Explicit Nutrient Source Estimate Maps in Journal of Geophysics: Biogeosciences (https://doi.org/10.1029/2019JG005134).