Missing Moist Soil Albedo Parameter

Matthew Lombardo

unread,

Sep 25, 2025, 12:44:08 PM (13 days ago) Sep 25

to QSWAT+

Hi everyone,

Does anyone know where I can find the moist soil albedo (alb) for a SSURGO soil, or if there is a default value that SWAT ? According to the link below this is a required parameter, but I can't find any data for it anywhere and there is no recommended default value.

https://swat.tamu.edu/media/69365/ch22_input_sol.pdf

Nancy B. Sammons

unread,

Sep 25, 2025, 2:02:05 PM (13 days ago) Sep 25

to Matthew Lombardo, QSWAT+

Matthew:

I am definitely not a soils expert, but I see in the SWAT+ source code that the default is set to 0.1.

There are two lines of code to confirm this that I have listed below:

SOIL_DATA_MODULE.F90

type soilayer_db

real :: z = 1500. !! mm |depth to bottom of soil layer

real :: bd = 1.3 !! Mg/m**3 |bulk density of the soil

real :: awc = 0.2 !! mm H20/mm soil |available water capacity of soil layer

real :: k = 10.0 !! mm/hr |saturated hydraulic conductivity of soil layer. Index:(layer,HRU)

real :: cbn = 2.0 !! % |percent organic carbon in soil layer

real :: clay = 10. !! none |fraction clay content in soil material (UNIT CHANGE!)

real :: silt = 60. !! % |percent silt content in soil material

real :: sand = 30. !! none |fraction of sand in soil material

real :: rock = 0. !! % |percent of rock fragments in soil layer

real :: alb = 0.1 !! none |albedo when soil is moist ß

real :: usle_k = 0.2 !! |USLE equation soil erodibility (K) factor

real :: ec = 0. !! dS/m |electrical conductivity of soil layer

real :: cal = 0. !! % |soil CaCo3

real :: ph = 0. !! |soil Ph

end type soilayer_db

SOIL_DB_READ.F90

if (sol(isol)%s%alb < 0.1) sol(isol)%s%alb = 0.1

I hope this helps.

Nancy

ß

--
You received this message because you are subscribed to the Google Groups "QSWAT+" group.
To unsubscribe from this group and stop receiving emails from it, send an email to qswatplus+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/qswatplus/f7823ac8-88af-4453-8738-592747fb3387n%40googlegroups.com.

Matthew Lombardo

unread,

Sep 27, 2025, 10:22:43 PM (11 days ago) Sep 27

to QSWAT+

Hi Nancy,

This definitely helps, thank you! Do you know if SWAT+ accepts ranges for the parameters? The source for the data that I found only has ranges with no median, so I've been using the average in my usersoil table.