Soil Water Capacity

Author: O.Conrad (c) 2020
Menu: Grid | Analysis | Soil Analysis

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

	Name	Type	Identifier	Description	Constraints
Input	Sand	grid, input, optional	`SAND`	[%]	-
	Silt	grid, input, optional	`SILT`	[%]	-
	Clay	grid, input, optional	`CLAY`	[%]	-
	Soil Organic Carbon	grid, input, optional	`CORG`	[permille]	-
	Bulk Density	grid, input, optional	`BULK`	[kg/m_]	-
	Cation Exchange Capacity	grid, input, optional	`CEC`	[cmol/kg]	-
	pH	grid, input, optional	`PH`	-	-
Output	Field Capacity	grid, output	`FC`	-	-
	Permanent Wilting Point	grid, output	`PWP`	-	-
	Water Capacity at Saturation	grid, output, optional	`THETA_S`	-	-
Options	Grid System	grid system	`PARAMETERS_GRID_SYSTEM`	-	-
	Default	floating point number	`SAND_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 15.000000
	Default	floating point number	`SILT_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 37.000000
	Default	floating point number	`CLAY_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 48.000000
	Default	floating point number	`CORG_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 1000.000000 Default: 15.000000
	Default	floating point number	`BULK_DEFAULT`	default value if no grid has been selected	Minimum: 100.000000 Maximum: 2650.000000 Default: 1350.000000
	Default	floating point number	`CEC_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 45.000000
	Default	floating point number	`PH_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 14.000000 Default: 6.400000
	Output Unit	choice	`UNIT`	-	Available Choices: [0] cubic-meter per cubic-meter [1] percentage of volume Default: 1
	Pedo-Transfer Function	choice	`FUNCTION`	-	Available Choices: [0] Hodnett & Tomasella 2002 [1] Toth et al. 2015 Default: 0
	Soil Moisture Potential	floating point number	`PSI_FC`	[hPa]	Minimum: 0.000000 Default: 316.000000
	Soil Moisture Potential	floating point number	`PSI_PWP`	[hPa]	Minimum: 0.000000 Default: 15850.000000
	Adjustments	boolean	`ADJUST`	Specifies whether to correct values of textures and bulk density to avoid creating nonsensical values.	Default: 1
	User Defined Coefficients	boolean	`USERDEF`	-	Default: 0
	User Defined Coefficients	static table	`COEFFICIENTS`	-	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

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