Date created: August 29, 2022
Date updated: April 7, 2023

Danica Schaffer-Smith
d.schaffer-smith@tnc.org


## PURPOSE:

Supporting data for "Landscape pollution source dynamics highlight priority 
locations for basin-scale interventions to protect water quality under 
hydroclimatic variability".

The Nature Conservancy and Arizona State University developed the Cape Fear 
River Basin Water Quantity and Quality SWAT Model (CFRB SWAT WQQ Model) to 1) 
understand hydrology and water quality across the basin under contemporary land 
use and management subject to a variety of weather conditions, and 2) identify 
locations where landscape interventions, such as large-scale wetland and forest 
restoration could help improve water quality under climate change.


## SIMULATIONS: 

To examine baseline conditions and to generate a water quality risk index (WQRI)
to identify intervention priorities in the CFRB, the model was run at a daily 
time step from January 1, 1979 to December 31, 2019 with the first three years 
serving as a model warm-up period. To assess the relative importance of point 
vs. non-point sources, the model was run again without point sources for the 
period January 1, 2010 to December 31, 2019. 

SWAT simulation results incorporated in the analysis for the publication include:
-Predicted daily contributions of runoff, sediment, and nutrient loads from each
subbasin for the years 1982-2019.
-Predicted daily flow, and in-stream loads of sediment and nutrients in each 
reach within the stream network for the years 1982-2019.
-Predicted daily flow, and loads of sediment and nutrients in reservoir outflow
 for the years 1982-2019.
-Predicted daily flow, and in-stream loads of sediment and nutrients in each 
reach within the stream network for the years 2010-2019, without point sources.
-Predicted daily flow, and loads of sediment and nutrients in reservoir outflow
 for the years 2010-2019, without point sources.

SWAT output files and data fields are described in detail in the SWAT 2012 
documentation available from:
https://swat.tamu.edu/media/69296/swat-io-documentation-2012.pdf


## FILE CONTENTS:

# SWAT Simulation Output

"baseline_sub_data_reformatted_1982-2019.csv" provides daily subbasin output from January 1, 1982 to December 31, 
2019. There are 2928 subbasins in the CFRB SWAT WQQ Model. 

date = date YYYY-MM-DD
yday = year day (1-366)
month = month of the year (1-12)
SUB = unique ID for the subbasin (matches reach ID) in the SWAT model
AREA = area of the subbasin in square kilometers
PRECIPmm = precipitation in millimeters
SNOMELTmm = snow melting during time step (water equivalent in millimeters)
PETmm = potential evapotranspiration in millimeters
ETmm = actual evapotranspiration in millimeters
SWmm = soil water content in millimeters
PERCmm = water percolating past the root zone in millimeters
SURQmm = surface runoff contribution to streamflow in millimeters
GW_Qmm = groundwater contribution to streamflow in millimeters
WYLDmm = water yield in millimeters
SYLDt_ha = sediment yield in metric tons per hectare
ORGNkg_ha = organic nitrogen load in kilograms per hectare
ORGPkg_ha organic phosphorus load in kilograms per hectare
NSURQkg_ha = NO3 in surface runoff in kilograms per hectare
SOLPkg_ha = soluble phosphorus yield in kilograms per hectare
SEDPkg_ha = mineral phosphorus yield in kilograps per hectare
LATQmm = lateral flow contribution to streamflow in millimeters
LATNO3kg_h = NO3 in lateral flow in kilograms per hectare
GWNO3kg_ha = NO3 in groundwater in kilograms per hectare
CHOLAmic_L = chlorophyll-a loading in kilograms
CBODUmg_L = carbonaceous biological oxygen demand loading in kilograms
DOXQmg_L = dissolved oxygen loading in kilograms
TNO3kg_ha = NO3 in tile flow in kilograms per hectare

"baseline_rch_and_rsv_data_reformatted_1982-2019.csv" provides daily combined 
reach and reservoir output simulation at the reach scale. There are 2928 reaches
in the stream network in the CFRB WQQ SWAT Model. The reach identifier (RCH) 
matches the identifier for the subbasin that contains each reach. 

Fields:
date = date YYYY-MM-DD
yday = year day (1-366)
month = month of the year (1-12)
RCH = unique ID for the reach (matches subbasin ID) in the SWAT model
FLOW_OUTcms = streamflow in cubic meters per second
ORGN_OUTkg = organic nitrogen load in kilograms
ORGP_OUTkg = organic phosphorus load in kilograms
NO3_OUTkg = nitrate load in kilograms
NH4_OUTkg = ammonium load in kilograms
NO2_OUTkg = nitrite load in kilograms
MINP_OUTkg = mineral phosphorus load in kilograms
SED_OUTtons = sediment load in metric tons

"baseline_rch_and_rsv_data_no_pt_source_reformatted_2010-2019.csv" " provides in-stream 
simulation output January 1, 2010 to December 31, 2019 without point sources. 

Fields:
date = date YYYY-MM-DD
yday = year day (1-366)
month = month of the year (1-12)
RCH = unique ID for the reach (matches subbasin ID) in the SWAT model
FLOW_OUTcms = streamflow in cubic meters per second
ORGN_OUTkg = organic nitrogen load in kilograms
ORGP_OUTkg = organic phosphorus load in kilograms
NO3_OUTkg = nitrate load in kilograms
NH4_OUTkg = ammonium load in kilograms
NO2_OUTkg = nitrite load in kilograms
MINP_OUTkg = mineral phosphorus load in kilograms
SED_OUTtons = sediment load in metric tons

# Spatial Data

SWAT simulation output can be represented spatially by linking simulation output 
to geospatial data. 

"subbasins.shp" contains the model subbasin shapefile (NC State Plane US Feet). 
The field 'SUB' contains the unique identifier for the subbasin that matches the 
'SUB' field in the subbasin output.

Fields:
SUB = unique identifier for the subbasin (1-2928)
AREA = subbasin area in hectares

"reach.shp" contains the model reach shapefile (NC State Plane US Feet). The 
field 'RCH' contains the unique identifier for the reach that matches the 
'RCH' field in the reach output.

Fields:
RCH = unique identifier for the reach and subbasin (1-2928)
FROM_NODE = unique identifer for the subbasin the reach occurs in
TO_NODE = unique identifer of the next subbasin downstream
AreaC = cumulated drainage area in hectares