Tool Soil Water Capacity

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.

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

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^3]	-
	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	`SAND_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 15.000000
	Default	Floating point	`SILT_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 37.000000
	Default	Floating point	`CLAY_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 100.000000 Default: 48.000000
	Default	Floating point	`CORG_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Maximum: 1000.000000 Default: 15.000000
	Default	Floating point	`BULK_DEFAULT`	default value if no grid has been selected	Minimum: 100.000000 Maximum: 2650.000000 Default: 1350.000000
	Default	Floating point	`CEC_DEFAULT`	default value if no grid has been selected	Minimum: 0.000000 Default: 45.000000
	Default	Floating point	`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	`PSI_FC`	[hPa]	Minimum: 0.000000 Default: 316.000000
	Soil Moisture Potential	Floating point	`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
(*) optional

Command-line

Usage: saga_cmd grid_analysis 27 [-SAND <str>] [-SAND_DEFAULT <double>] [-SILT <str>] [-SILT_DEFAULT <double>] [-CLAY <str>] [-CLAY_DEFAULT <double>] [-CORG <str>] [-CORG_DEFAULT <double>] [-BULK <str>] [-BULK_DEFAULT <double>] [-CEC <str>] [-CEC_DEFAULT <double>] [-PH <str>] [-PH_DEFAULT <double>] [-FC <str>] [-PWP <str>] [-THETA_S <str>] [-UNIT <str>] [-FUNCTION <str>] [-PSI_FC <double>] [-PSI_PWP <double>] [-ADJUST <str>] [-USERDEF <str>] [-COEFFICIENTS <str>]
  -SAND:<str>           	Sand
	Grid, input, optional
  -SAND_DEFAULT:<double>	Default
	Floating point
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 15.000000
  -SILT:<str>           	Silt
	Grid, input, optional
  -SILT_DEFAULT:<double>	Default
	Floating point
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 37.000000
  -CLAY:<str>           	Clay
	Grid, input, optional
  -CLAY_DEFAULT:<double>	Default
	Floating point
	Minimum: 0.000000
	Maximum: 100.000000
	Default: 48.000000
  -CORG:<str>           	Soil Organic Carbon
	Grid, input, optional
  -CORG_DEFAULT:<double>	Default
	Floating point
	Minimum: 0.000000
	Maximum: 1000.000000
	Default: 15.000000
  -BULK:<str>           	Bulk Density
	Grid, input, optional
  -BULK_DEFAULT:<double>	Default
	Floating point
	Minimum: 100.000000
	Maximum: 2650.000000
	Default: 1350.000000
  -CEC:<str>            	Cation Exchange Capacity
	Grid, input, optional
  -CEC_DEFAULT:<double> 	Default
	Floating point
	Minimum: 0.000000
	Default: 45.000000
  -PH:<str>             	pH
	Grid, input, optional
  -PH_DEFAULT:<double>  	Default
	Floating point
	Minimum: 0.000000
	Maximum: 14.000000
	Default: 6.400000
  -FC:<str>             	Field Capacity
	Grid, output
  -PWP:<str>            	Permanent Wilting Point
	Grid, output
  -THETA_S:<str>        	Water Capacity at Saturation
	Grid, output, optional
  -UNIT:<str>           	Output Unit
	Choice
	Available Choices:
	[0] cubic-meter per cubic-meter
	[1] percentage of volume
	Default: 1
  -FUNCTION:<str>       	Pedo-Transfer Function
	Choice
	Available Choices:
	[0] Hodnett & Tomasella 2002
	[1] Toth et al. 2015
	Default: 0
  -PSI_FC:<double>      	Soil Moisture Potential
	Floating point
	Minimum: 0.000000
	Default: 316.000000
  -PSI_PWP:<double>     	Soil Moisture Potential
	Floating point
	Minimum: 0.000000
	Default: 15850.000000
  -ADJUST:<str>         	Adjustments
	Boolean
	Default: 1
  -USERDEF:<str>        	User Defined Coefficients
	Boolean
	Default: 0
  -COEFFICIENTS:<str>   	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