VFS {VFS}R Documentation

Vegetated filter strip and erosion model

Description

Simulated erosion and runoff given climate and soil texture, with or without a vegetated filter strip in place.

Usage

VFS(nyears = 1000, thissoil, thisbuffer, rain, temperature, 
  Duration = 2, FieldArea = 4000, VFSwidth = 10.7, VFSslope = 0.02,
  FieldSlope,  z = 1000, a = 1, b = 1.5,
  carrysoilwater = TRUE, runoffcalc = TRUE)

Arguments

nyears

Number of years to simulate.

thissoil

Soil properties for the site, as from soildat.

thisbuffer

Vegetation properties for the buffer strip, as from bufferdat.

rain

Daily rainfall (mm).

temperature

Daily mean temperature (C).

Duration

Rainfall event length. Default is 2 hours.

FieldArea

Field area (m^2).

VFSwidth

Filter strip width (m).

VFSslope

Filter strip slope (m/m).

FieldSlope

Optional field slope (m/m). If missing, VFSslope will be used.

z

Rooting zone depth (mm). Default is 1000 mm.

a

Empirical parameter that relates concentration and flow in the concentration-discharge relationship, C = aQ^b.

b

Empirical parameter that relates concentration and flow in the concentration-discharge relationship, C = aQ^b. May be a single value or a vector of values.

carrysoilwater

Boolean describing whether to store soil water; if FALSE, soil is always at field capacity. This option allows the effect of soil water storage to be quantified.

runoffcalc

Boolean describing whether to use intensity and saturation exceedances; if FALSE, all rainfall becomes runoff. This option allows the effect of runoff calculation to be quantified.

Details

The concentration-discharge (C-Q) model of erosion is intended to produce relative erosion values, rather than absolute values, but will produce absolute values if a and b are known. The MUSLE field erosion model is run alongside the C-Q model. The K factor is estimated from soil texture data using MUSLE.K, and the LS factor from field properties using MUSLE.LS. Blaney-Criddle coefficients for evapotranspiration calculations from a cornfield are hard-coded; a future update will allow for varying the type of field.

Value

Returns an object of class VFS, comprising:

daily

Daily output of all public variables that change as a function of time. The data frame has columns:

field

Data on the field being modeled:

Conc

Sediment concentration (in mass/volume) as calculated by the relationship C = aQ^b; specific units depend on units conversions included in the value of a.

MassIn

Sediment load (mass) from the C-Q model, as calculated by multiplying concentration and runoff volume. If concentration is assumed to be in g/L, then the load is calculated in g.

MassOut

Sediment mass from the C-Q model that leaves the vegetated filter strip at the end of a runoff event (i.e., the mass that is not removed).

MassRemoved

Sediment mass from the C-Q model that remains in the vegetated filter strip at the end of a runoff event.

AnnualMassIn

Sum of the sediment loads from the C-Q model entering the vegetated filter strip over the course of one year.

AnnualMassOut

Sum of the sediment loads from the C-Q model leaving the vegetated filter strip over the course of one year.

AnnualRemovalEfficiency

The removal effficiency from the C-Q model of the vegetated filter strip at an annual time scale (%).

MassInMUSLE

Sediment mass from the MUSLE model leaving the crop field .

MassOutMUSLE

Sediment mass from the MUSLE model that leaves the vegetated filter strip at the end of a runoff event (t/day).

MassRemovedMUSLE

Sediment mass that remains in the vegetated filter strip at the end of a runoff event (t/day).

AnnualMassInMUSLE

Sum of the sediment loads entering the vegetated filter strip over the course of one year (t).

AnnualMassOutMUSLE

Sum of the sediment loads leaving the vegetated filter strip over the course of one year (t).

AnnualRemovalEfficiencyMUSLE

The removal effficiency of the vegetated filter strip at an annual time scale (%).

Ftannual

Filter strip removal efficiency.

Ftannualavg

The average of all per-event trapping efficiencies over the course of one year.

Author(s)

Heather Gall, Sarah Goslee, and Tamie Veith

References

Gall, H. E., Schultz, D., Veith, T. L, Goslee, S. C., Mejia, A., Harman, C. J., Raj, C. and Patterson, P. H. (2018) The effects of disproportional load contributions on quantifying vegetated filter strip sediment trapping efficiencies. Stoch Environ Res Risk Assess 32(8), 2369–2380. doi: 10.1007/s00477-017-1505-x

Haan C. T., Barfield B. J. and Hayes J. C. (1994) Design hydrology and sedimentology for small catchments. Acad Press, San Diego.

Williams, J. R. (1975) Sediment-yield prediction with universal equation using runoff energy factor. Pp. 244–251 in: Present and prospective technology for predicting sediment yield and sources. ARS.S-40, US Gov. Print. Office, Washington, DC. 244-252.

Wischmeier, W. H. and Smith, D. D. (1978) Predicting rainfall erosion losses-a guide to conservation planning. U.S. Department of Agriculture, Agriculture Handbook No. 537.

See Also

print.VFS, summary.VFS, wth.param, soildat, bufferdat,

Examples


# state college GHCN data
#
# weather <- read.dly(system.file("extdata", "USC00368449.dly", package = "VFS"))
data("weather") # same object

weather.param <- wth.param(weather, method="markov")

rain.compare <- rainfall(365*2, weather.param)
temp.compare <- temperature(365*2, weather.param)

data(soildat)
data(bufferdat)

# bluegrass buffer, clay loam soil
# short simulation to cut down on time required
vfs.CL <- VFS(nyears = 2, thissoil = subset(soildat, Soil == "CL"), 
rain=rain.compare, temperature=temp.compare, 
thisbuffer = subset(bufferdat, Species == "bluegrass"), Duration = 2, 
FieldArea = 4000, VFSwidth = 10.7, VFSslope = 0.02, 
z = 1000, b = 1.5)

print(vfs.CL)
summary(vfs.CL)

aple.CL <- VFSAPLE(vfs.CL, soilP = 120, OM = 2)

print(aple.CL)
summary(aple.CL)


[Package VFS version 1.0.2 Index]