Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.

[Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

ASPECT_DEGREES Gages-II Topo

Mean watershed aspect, degrees (degrees of the 

compass, 0-360). Derived from 100-m resolution 

National Elevation Data. 0 and 360 point to north. 

Because of the national Albers projection, actual aspect 

may vary. X

AWCAVE Gages-II Soils

Average value for the range of available water capacity 

for the soil layer or horizon (inches of water per inches 

of soil depth). X

BAS_COMPACTNESS Gages-II Bas_Morph

Watershed compactness ratio, 100 times the area 

divided by the squared perimeter; higher values 

represent a more compact shape. X

BDAVE Gages-II Soils

Average value of bulk density (grams per cubic 

centimeter). X X

CDL_CORN Gages-II LC_Crops

Percent of the watershed classified as corn cropland. 

Class 1 of the 2009 USDA NASS Cropland Data Layer. X X

CDL_OTHER_HAYS Gages-II LC_Crops

Percent of the watershed classified as other hays 

cropland. Class 37 of the 2009 USDA NASS Cropland 

Data Layer. X

CDL_PASTURE_GRASS Gages-II LC_Crops

Percent of the watershed classified as pasture/grass 

cropland. Class 62 of the 2009 USDA NASS Cropland 

Data Layer. X

CDL_SOYBEAN Gages-II LC_Crops

Percent of the watershed classified as soybeans 

cropland. Class 5 of the 2009 USDA NASS Cropland 

Data Layer. X X

CLAYAVE Gages-II Soils Average value of clay content (percentage). X X

CONTACT Gages-II Hydro

Subsurface flow contact time index. The subsurface 

contact time index estimates the number of days that 

infiltrated water resides in the saturated subsurface 

zone of the basin before discharging into the stream. X X

CORNSOYBEAN_index Derived (Gages-II) LC06_Basin Summation of CDL_CORN and CDL_SOYBEANS. X X
Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.—Continued

[Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

CROPSNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as cultivated 

crops (class 82). X

DECIDNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as deciduous 

forest (class 41). X X

DRAIN_SQKM Gages-II BasinID

Watershed drainage area, sq km, as delineated in our 

basin boundary. X X

ELEV_MAX_M Gages-II Topo

Maximum watershed elevation (meters) from 100-m 

National Elevation Dataset. X

ELEV_MEAN_M_BASIN Gages-II Topo

Mean watershed elevation (meters) from 100-m 

National Elevation Dataset. X X

ELEV_MEDIAN_M_BASIN Gages-II Topo

Median watershed elevation (meters) from 100-m 

National Elevation Dataset. X X

ELEV_MIN_M Gages-II Topo

Minimum watershed elevation (meters) from 100-m 

National Elevation Dataset (may include sinks). X

EVERGRNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as evergreen 

forest (class 42). X

FORESTNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as forested. 

(Sum of classes 41, 42, and 43.) X

FracP Derived (Gages-II) Climate

Monthly precipitation (12 values) as a fraction of 

annual total precipitation. X

FROST_index Derived (Gages-II) Climate

Number of days between first frost (FST32F_BASIN) and 

last frost (LST32F_BASIN). X X

FST32F_BASIN Gages-II Climate

Watershed average of mean day of the year of first 

freeze, derived from 30 years of record (1961-1990), 2-

km PRISM. For example, value of 300 is the 300th day 

of the year (Oct 27th). X X

GRASSNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as herbaceous 

(grassland) (class 71). X

JAN_TMP7100_DEGC Gages-II Climate

Average January (1971-2000) air temperature for the 

watershed, degrees C; derived from 800-m PRISM data. X
Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.—Continued

[Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

JUL_TMP7100_DEGC Gages-II Climate

Average July (1971-2000) air temperature for the 

watershed, degrees C; derived from 800-m PRISM data. X

KFACT_UP Gages-II Soils

Average K-factor value for the uppermost soil horizon 

in each soil component. K-factor is an erodibility factor 

that quantifies the susceptibility of soil particles to 

detachment and movement by water. The K-factor is 

used in the Universal Soil Loss Equation (USLE) to 

estimate soil loss by water. Higher values of K-factor 

indicate greater potential for erosion. X X

LAND_index Derived (Gages-II) LC06_Basin

Summation of WOODYWETNLCD06 and 

EVERGRNLCD06. X

LST32F_BASIN Gages-II Climate

Watershed average of mean day of the year of last 

freeze, derived from 30 years of record (1961-1990), 2-

km PRISM. For example, value of 100 is the 100th day 

of the year (April 10th). X X

MAR_PPT7100_CM Gages-II Climate

Average March (1971-2000) precipitation (cm) for the 

watershed; derived from 800-m PRISM data. X

MonP Derived (Gages-II) Climate

Average precipitation (cm) for the watershed for each 

month (12 values); derived from 800-m PRISM data. X

MonT Derived (Gages-II) Climate

Average air temperature (1971-2000) for the 

watershed for each month (12 values), degrees C; 

derived from 800-m PRISM data. X

OCT_PPT7100_CM Gages-II Climate

Average October (1971-2000) precipitation (cm) for the 

watershed; derived from 800-m PRISM data. X

OMAVE Gages-II Soils

Average value of organic matter content (percent by 

weight). X X

PASTURENLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as pasture or 

hay (class 81). X X
Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.—Continued

\ [Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

GEOPERM Gleeson et al. (2011) Geology Geological permeability. X X

PERMAVE Gages-II Soils Average permeability (inches/hour). X X

PET Gages-II Climate

Mean-annual potential evapotranspiration (PET), 

estimated using the Hamon (1961) equation. X X

PLANTNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as planted or 

cultivated (agriculture). (Sum of classes 81 and 82.) X X

PPT_index Derived (Gages-II) Climate

Difference between March and October precipitation 

as a fraction of the average precipitation. X X

PPTAVG_BASIN Gages-II Climate

Mean annual precip (cm; 1971-2000) for the 

watershed, from 800-m PRISM data. X X

PRECIP_SEAS_IND Gages-II Climate

Precipitation seasonality index. Index of how much 

annual precipitation falls seasonally (high values) or 

spread out over the year (low values). Based on 

monthly precipitation values from 30-year (1971-2000) 

PRISM. Range is 0 (precipitation is spread out exactly 

evenly in each month) to 1 (all precipitation falls in a 

single month). X

RELIEFFT Derived (Gages-II) Topo

Basin relief. (Maximum elevation minus minimum 

elevation.) X X

RFACT Gages-II Soils

Average annual (1971-2000) rainfall and runoff factor 

("R factor" of USLE). X X

RH_BASIN Gages-II Climate

Watershed average (1971-2000) relative humidity 

(percent), from 2-km PRISM. X X

ROCKDEPAVE Gages-II Soils Average value of total soil thickness examined (inches). X X

RRMEAN Gages-II Topo

Dimensionless elevation relief ratio, calculated as as 

the difference between mean and minimum elevation 

divided by the full range of elevations. X X
Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.—Continued

[Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

RRMEDIAN Gages-II Topo

Dimensionless elevation relief ratio, calculated as as 

the difference between median and minimum 

elevation divided by the full range of elevations. X X

SANDAVE Gages-II Soils Average sand content of soils (percentage). X X

SHRUBNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as shrubland 

(class 52). X

SILTAVE Gages-II Soils Average silt content of soils (percentage). X X

SLOPE_PCT Gages-II Topo

Mean watershed slope, percent; derived from 100-m 

resolution National Elevation Dataset. X X

SNOW_PCT_PRECIP Gages-II Climate

Estimated snow as a percent of total precipitation, 

mean for period 1901-2000 on a 1-km grid. X

StanP Derived (Gages-II) Climate

Monthly precipitation, standardized by mean and 

standard deviation of monthly precipitation. X

StanT Derived (Gages-II) Climate

Monthly average temperature standardized by mean 

and standard deviation of monthly average 

temperature. X

T_AVG_BASIN Gages-II Climate

Average annual air temperature (1971-2000) for the 

watershed, degrees C; derived from 2-km PRISM data. X X

T_index Derived (Gages-II) Climate

Difference between the average July temperature and 

January temperature, less the basin average 

temperature. X X

T_MAX_BASIN Gages-II Climate

Watershed average of maximum monthly air 

temperature (degrees C, 1971-2000) from 800-m PRISM 

data. X X

T_MIN_BASIN Gages-II Climate

Watershed average of minimum monthly air 

temperature (degrees C, 1971-2000) from 800-m PRISM 

data. X X
Appendix B. A description of all basin characteristics considered as potential explanatory variables in the various regressions conducted as part of the 

Southeast Model Comparison.—Continued

[Gages-II can be found in Falcone and others (2009) and in Falcone (2011). cm, centimeter; m, meter]

Variable Name Source Class Description FDC Regressions Moment Regressions

TOPWET Gages-II Hydro

Topographic wetness index. Calculated as ln(a/S), 

where "ln" is the natural log, "a" is the upslope area per 

unit contour length and "S" is the slope at that point. 

See 

http://ks.water.usgs.gov/Kansas/pubs/reports/wrir.99-

4242.html for more detail. X X

WATERNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as open water 

(class 11). X X

WOODYWETNLCD06 Gages-II LC06_Basin

Percentage of the watershed classified as woody 

wetlands (class 90). X X

WTDEPAVE Gages-II Soils

Average value of depth to seasonally high water table 

(feet). X X