Soil Water Capacity (Grid Collections)

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 28 [-SAND ] [-SILT ] [-CLAY ] [-CORG ] [-BULK ] [-CEC ] [-PH ] [-FC ] [-PWP ] [-THETA_S ] [-UNIT ] [-FUNCTION ] [-PSI_FC ] [-PSI_PWP ] [-ADJUST ] [-USERDEF ] [-COEFFICIENTS ]
  -SAND:           Sand
	grid collection, input
  -SILT:           Silt
	grid collection, input
  -CLAY:           Clay
	grid collection, input
  -CORG:           Soil Organic Carbon
	grid collection, input
  -BULK:           Bulk Density
	grid collection, input
  -CEC:            Cation Exchange Capacity
	grid collection, input
  -PH:             pH
	grid collection, input
  -FC:             Field Capacity
	grid collection, output
  -PWP:            Permanent Wilting Point
	grid collection, output
  -THETA_S:        Water Capacity at Saturation
	grid collection, 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