Soil Water Capacity

Description

This tool derives the soil water capacity for the given soil moisture potentials (psi) based on pedo-transfer functions. Suggested psi values for field capacity estimation range between 60 hPa (pF=1.8) and 316 hPa (pF=2.5). For permanent wilting point estimation take a psi value of about 15850 hPa (pF=4.2). This tool re-implements the R-script AWCPTF by Hengl as well as the regression approach by Toth et al. (2015). See Hengl et al. (2017), Woesten & Verzandvoort (2013) and Toth et al. (2015) for more details.

References

R-Script AWCPTF {GSIF} by J. Leenaars, M. Ruiperez Gonzalez and T. Hengl

Hengl, T., Mendes de Jesus, J., Heuvelink, G.B.M., Ruiperez Gonzalez, M., Kilibarda, M., Blagotic, A., et al. (2017): SoilGrids250m: Global gridded soil information based on machine learning. PLoS ONE 12(2): e0169748. doi:10.1371/journal.pone.0169748

Hodnett, M.G., Tomasella, J. (2002): Marked differences between van Genuchten soil water-retention parameters for temperate and tropical soils: A new water-retention pedo-transfer functions developed for tropical soils. Geoderma 108(3):155-180. doi:10.1016/S0016-7061(02)00105-2

Toth, B., Weynants, M., Nemes, A., Mako, A., Bilas, G., Toth, G. (2015): New generation of hydraulic pedotransfer functions for Europe. European Journal of Soil Science, 66, 226–238. doi:10.1111/ejss.12192

Toth, B., Weynants, M., Pasztor, L, Hengl, T. (2017): 3D soil hydraulic database of Europe at 250 m resolution. Hydrological Processes, 31:2662–2666. doi:10.1002/hyp.11203

Woesten, J.H.M., Verzandvoort, S.J.E., Leenaars, J.G.B., Hoogland, T., Wesseling, J.G. (2013): Soil hydraulic information for river basin studies in semi-arid regions. Geoderma 195:79-86. doi:10.1016/j.geoderma.2012.11.021

Parameters

Command Line

Usage: saga_cmd grid_analysis 27 [-SAND ] [-SAND_DEFAULT ] [-SILT ] [-SILT_DEFAULT ] [-CLAY ] [-CLAY_DEFAULT ] [-CORG ] [-CORG_DEFAULT ] [-BULK ] [-BULK_DEFAULT ] [-CEC ] [-CEC_DEFAULT ] [-PH ] [-PH_DEFAULT ] [-FC ] [-PWP ] [-THETA_S ] [-UNIT ] [-FUNCTION ] [-PSI_FC ] [-PSI_PWP ] [-ADJUST ] [-USERDEF ] [-COEFFICIENTS ]
  -SAND:              Sand
	grid, input, optional
  -SAND_DEFAULT:   Default
	floating point number
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 15.000000
  -SILT:              Silt
	grid, input, optional
  -SILT_DEFAULT:   Default
	floating point number
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 37.000000
  -CLAY:              Clay
	grid, input, optional
  -CLAY_DEFAULT:   Default
	floating point number
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 48.000000
  -CORG:              Soil Organic Carbon
	grid, input, optional
  -CORG_DEFAULT:   Default
	floating point number
	Minimum: 0.000000
	Maximum: 1000.000000
	Default: 15.000000
  -BULK:              Bulk Density
	grid, input, optional
  -BULK_DEFAULT:
                           Default
                           	floating point number
                           	Minimum: 100.000000
                           	Maximum: 2650.000000
                           	Default: 1350.000000
  -CEC:               Cation Exchange Capacity
	grid, input, optional
  -CEC_DEFAULT:    Default
	floating point number
	Minimum: 0.000000
	Default: 45.000000
  -PH:                pH
	grid, input, optional
  -PH_DEFAULT:     Default
	floating point number
	Minimum: 0.000000
	Maximum: 14.000000
	Default: 6.400000
  -FC:                Field Capacity
	grid, output
  -PWP:               Permanent Wilting Point
	grid, output
  -THETA_S:           Water Capacity at Saturation
	grid, output, optional
  -UNIT:
                           Output Unit
                           	choice
                           	Available Choices:
                           	[0] cubic-meter per cubic-meter
                           	[1] percentage of volume
                           	Default: 1
  -FUNCTION:
                           Pedo-Transfer Function
                           	choice
                           	Available Choices:
                           	[0] Hodnett & Tomasella 2002
                           	[1] Toth et al. 2015
                           	Default: 0
  -PSI_FC:         Soil Moisture Potential
	floating point number
	Minimum: 0.000000
	Default: 316.000000
  -PSI_PWP:        Soil Moisture Potential
	floating point number
	Minimum: 0.000000
	Default: 15850.000000
  -ADJUST:            Adjustments
	boolean
	Default: 1
  -USERDEF:           User Defined Coefficients
	boolean
	Default: 0
  -COEFFICIENTS:
                           User Defined Coefficients
                           	static table
                           	4 Fields:
                           	- 1. [8 byte floating point number] ln(alpha)
                           	- 2. [8 byte floating point number] ln(n)
                           	- 3. [8 byte floating point number] theta s
                           	- 4. [8 byte floating point number] theta r