soilwater5 | R Documentation |
Function to calculate the soil water content based on the modified van Genuchten's formula, as suggested by Pierson and Mulla (1989):
θ = θ_R + (θ_S - θ_R)(1 + (α x)^n)^{-m} + b_0 + b_1 x + b_2 * x^2
soilwater5(x, theta_R, theta_S, alpha, n, m = 1 - 1/n, b0, b1, b2)
x |
the matric potential. |
theta_R |
the residual water content. |
theta_S |
the water content at saturation. |
alpha |
a scale parameter of the van Genuchten's formula. |
n |
a shape parameter in van Genuchten's formula. |
m |
a shape parameter in van Genuchten's Formula. Default is 1-1/n (Mualem, 1976). |
b0 |
a parameter added to the van Ganuchten's formula. |
b1 |
a parameter added to the van Ganuchten's formula. |
b2 |
a parameter (of quadratic term) added to the van Ganuchten's formula. |
The the soil water content or the saturation index (a value between 0 and 1).
Anderson Rodrigo da Silva <anderson.agro@hotmail.com>
Pierson, F.B.; Mulla, D.J. (1989) An Improved Method for Measuring Aggregate Stability of a Weakly Aggregated Loessial Soil. Soil Sci. Soc. Am. J., 53:1825–1831.
fitsoilwater5
soilwater5(x = 20, theta_R = 0.2735, theta_S = 0.478, alpha = 0.1029, n = 9.45, b0 = 0.2278, b1 = -0.0165, b2 = 0.000248) curve(soilwater5(x, theta_R = 0.2735, theta_S = 0.478, alpha = 0.1029, n = 9.45, b0 = 0.2278, b1 = -0.0165, b2 = 0.000248), from = 0, to = 40, ylab = "Water content", xlab = "Matric potential") # End (Not run)
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