I would like to know why I am getting no data pixels in my soil wetness raster, since none of the source rasters used to calculate the SWI have no data values.
method I used: soil data from HWSD FAO used to derive depth and calculated soil hydraulic conductivty by SoilPAR program.
First made TWI: SRTM DEM-watershed clip-flow direction-flow accumulation
DEM-slope-slope radian-remove zero values from radian raster
then calculate TI with raster calculator: this gives a nice raster without No Data values:
For the STI I calculated the transmissivity (=soil hydraulic conductivity*soil dpeth*0.000864), again without No DATA values
Then I used raster calculator for
Ln[(average of transmissivity)(flowaccu)/(transmissivityslope)]
And suddenly everything is pixelated and there are No Data pixels everywhere. I understand that the lakes are NoData pixels but I don't think this should be the same for other places.
Why do I get them and how to prevent them?
