This file provides details on the source, delivery, and stream attenuation variables used in the MRB7 RF1 total nitrogen and total phosphorus models.


TOTAL NITROGEN MODEL

Source Variables

boundary_n: Mean annual total nitrogen load estimated at calibration stations located immediately downstream of the Canadian border. Catchments located upstream of these stations were not included in the model calibration.		

canbasin: Drainage area for watersheds with more than 50% located in Canada. This was modeled as a source variable.

atdep_load: Annual wet deposition of inorganic nitrogen (ammonia and nitrate, kg/yr), 2002. Data were compiled by the National Water Quality Assesment (NAWQA) program (Wieczorek and Lamotte, 2011).

ps_n_02_all: Surface-water discharges of total nitrogen from permitted wastewater discharge (kg/yr), 2002. Data were compiled by NAWQA (Maupin, M.A. and T. Ivahnenko, 2011).

farm_n: Nitrogen from commercial fertilizer applied to agricultural land (kg/yr), 2002. Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).

total_manure_n: Nitrogen from manure produced by livestock animals (kg/yr), 2002. Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).

nlcd_devel_km2: Area of developed land (square km) obtained from the 2001 National Land Cover Database (NLCD). Data were compiled by NAWQA (Wieczorek and Lamotte, 2011). 

west_nlcd_forest_km2: Area of forest land (square km) obtained from the 2001 NLCD located on the west side of the Cascade Range.
Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).

east_nlcd_forest_km2: Area of forest land (square km) obtained from the 2001 NLCD located on the east side of the Cascade Range.
Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).   

ALDER_M2: Basal area of red alder trees, 2001. Data were compiled by the MRB7 modeling team (Wise and Johnson, 2011).  

Delivery Variables

bHLR_HUMTPSI2_PCT: Percentage of watershed that consists of hydrologic landscape region 20 (humid mountains with permeable soil 
and impermeable bedrock). Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).  	
		
bln_prec_eff_cm: Natural log of effective mean annual precipitation (local precipitation plus the depth of irrigation water).
Data were compiled by NAWQA (Wieczorek and Lamotte, 2011) and the MRB7 modeling team (Wise and Johnson, 2011).


TOTAL PHOSPHORUS MODEL

Source Variables

boundary_p: Mean annual total phosphorus load estimated at calibration stations located immediately downstream of the Canadian border. Catchments located upstream of these stations were not included in the model calibration.		

canbasin: Drainage area for watersheds with more than 50% located in Canada. This was modeled as a source variable.

ps_p_02_all: Surface-water discharges of total phosphorus from permitted wastewater discharge (kg/yr), 2002. Data were compiled by NAWQA (Maupin, M.A. and T. Ivahnenko, 2011).

total_ag_p: Phosphorus from commercial fertilizer applied to agricultural land and produced by livestock animals (kg/yr), 2002. Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).

nlcd_devel_km2: Area of developed land (square km) obtained from the 2001 National Land Cover Database (NLCD). Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).

natural_p_load: Phosphorus content of geologic material, mass ppm scaled by catchment area. Data were compiled by the MRB7 modeling team (Wise and Johnson, 2011).  

Delivery Variables

ln_soil_permave: Natural log of mean soil permeability. Data were compiled by NAWQA (Wieczorek and Lamotte, 2011). 

bHLR_HUMTPSI2_PCT: Percentage of watershed that consists of hydrologic landscape region 20 (humid mountains with permeable soil and impermeable bedrock). Data were compiled by NAWQA (Wieczorek and Lamotte, 2011).  	
		
bln_prec_eff_cm: Natural log of effective mean annual precipitation (local precipitation plus the depth of irrigation water). Data were compiled by NAWQA (Wieczorek and Lamotte, 2011) and the MRB7 modeling team (Wise and Johnson, 2011).

Stream Attenuation Variables

rchdecay1: Phosphorus loss rate in streams (1/day) with mean annual streamflow less than 13.4 cubic meters per second.
											

References 

Maupin, M.A. and T. Ivahnenko, 2011. Nutrient Loadings to Streams of the Continental United States From Municipal and Industrial Effluent. Journal of the American Water Resources Association, doi: 10.1111/j.1752-1688.2011.00576.x.

Wieczorek, M. and A. Lamotte, 2011. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States (U.S. Geological Survey Digital Data Series DS-491). http://water.usgs.gov/nawqa/modeling/rf1attributes.html, accessed
June 1, 2008.

Wise, D.R. and H. M. Johnson, 2011. Surface-Water Nutrient Conditions 
and Sources in the United States Pacific Northwest. Journal of the American Water Resources Association (JAWRA) 1-26. DOI: 10.1111/
j.1752-1688.2011.00580.x