Soil water Retantion Curve and Unsaturated Hydraulic Conductivity

Description

Soil Water Retention Curve 'swc', Hydraulic Conductivity 'khy' , Soil Water Capacity 'cap' , Soil Water (Hydraulic) Diffusivity 'diffusivity'

Usage

swc(psi = 0.5, alpha = 1, n = 1.5, m = 1 - 1/n, theta_sat = 0.4,
  theta_res = 0.05, psi_s = -1/alpha, lambda = m * n,
  saturation_index = FALSE, type_swc = c("VanGenuchten", "BrooksAndCorey"),
  ...)

khy(psi = 0.5, v = 0.5, ksat = 0.01, alpha = 1, n = 1.5, m = 1 -
  1/n, theta_sat = 0.4, theta_res = 0.05, psi_s = -1/alpha, lambda = m *
  n, b = NA, type_swc = "VanGenuchten", type_khy = c("Mualem",
  "BrooksAndCorey"), ...)

cap(psi = 0.5, alpha = 1, n = 1.5, m = 1 - 1/n, theta_sat = 0.4,
  theta_res = 0.05, type_swc = "VanGenuchten", ...)

diffusivity(psi = 0.5, v = 0.5, ksat = 0.01, alpha = 1, n = 1.5,
  m = 1 - 1/n, theta_sat = 0.4, theta_res = 0.05, ...)

Arguments

Examples

library(soilwater)
soiltype <- c("sand","silty-sand","loam","clay")
theta_sat <- c(0.44,0.39,0.51,0.48)
theta_res <- c(0.02,0.155,0.04,0.10)
alpha <- c(13.8,6.88,9.0,2.7) # 1/meters
n <- c(2.09,1.881,1.42,1.29) 
m <- 1-1/n
v <- array(0.5,length(soiltype))
ks <- c(1.5e-1,1e-4*3600,3.3e-2,4.1e-4)/3600   # meters/seconds

psi <- -(1:2000)/1000

D <- as.data.frame(array(0.1,c(length(psi),length(soiltype))))
names(D) <- soiltype
for (it in names(D)) {
  
  i=which(names(D)==it)
  D[,i] <- diffusivity(psi=psi,
            v=v[i],ksat=ks[i],alpha=alpha[i],
            n=n[i],m=m[i],theta_sat=theta_sat[i],
            theta_res=theta_res[i])
 
}
# plot diffusivity on log scale 
lty <- 1:length(names(D) )

plot(psi,D[,1],lty=lty[1],main="Diffusvity vs psi",xlab="psi [m]",
ylab="D [m^2/s]",type="l",ylim=range(D),ylog=TRUE)
for (i in 2:ncol(D)) {
  lines(psi,D[,i],lty=lty[i]) 
}
legend("topleft",lty=lty,legend=names(D))
Dinv <- 1/D 

# pot diffusivity on log scale 
lty <- 1:length(names(D) )

plot(psi,Dinv[,1],lty=lty[1],main="1/Diffusvity vs psi",
xlab="psi [m]",ylab="1/D [s/m^2]",type="l",ylim=range(Dinv),ylog=TRUE)
for (i in 2:ncol(Dinv)) {
  lines(psi,Dinv[,i],lty=lty[i]) 
}
legend("topright",lty=lty,legend=names(D))

The water table recharge: the response unit

Description

The water table recharge: the response unit

Usage

unitResponse(t, d = 1, D = 1, H = d, m = 100)

Arguments

Note

This function calcletes the water-table recharge rate in a hillslope assuming:

1. Richards' Equation is linearized and reduced to the form of heat equation;

2. The diffusion water-table rate is connectedwith soil pressure head according with eq. 13 (Cordano and Rigon, 2008);

References

Cordano, E., and R. Rigon (2008), A perturbative view on the subsurface water pressure response at hillslope scale, Water Resour. Res., 44, W05407, doi:10.1029/2006WR005740. http://onlinelibrary.wiley.com/doi/10.1029/2006WR005740/pdf

Examples

library(soilwater)


t <- seq(0,2,by=0.001)
d <- c(1,0.75,0.5,0.25)
val1 <- unitResponse(t, d = d[1], D = 1, H = 1, m = 500)

val2 <- unitResponse(t, d = d[2], D = 1, H = 1, m = 500)

val3 <- unitResponse(t, d = d[3], D = 1, H = 1, m = 500)

val4 <- unitResponse(t, d = d[4], D = 1, H = 1, m = 500)

Water volume in function of water-table depth or height 'swc', Hydraulic Conductivity 'khy' , Soil Water Capacity 'cap' , Soil Water (Hydraulic) Diffusivity 'diffusivity'

Description

Water volume in function of water-table depth or height 'swc', Hydraulic Conductivity 'khy' , Soil Water Capacity 'cap' , Soil Water (Hydraulic) Diffusivity 'diffusivity'

Usage

watervolume(d = H - h, H = 1, h = NA, nstep = 100, Gamma = 1,
  soilwaterretentioncurve = swc, ...)

Arguments

Note

The water volume per topographical area unit obtained by vertical integration off soil water content profile

See Also

swc