SDR model runs correctly but in SDR “No valid pixels were received, sending None” phrase appears and there are no results in ‘sediment retention’ and ‘sediment ratio’ fields in the result DBF file
Hi @Nayanathara
It is helpful if you post the entire log file (.txt) that the model produces in the Workspace, that often provides information that can help us understand what’s happening, and lets us know which version of InVEST you’re using.
It looks like you are getting values for USLE for some of your watersheds but not others. If USLE is not calculated then sed_export and sed_retent cannot be calculated. So the first thing to do is look at the intermediate results, usle.tif output and your input layers and see if you can find any problems in these watersheds.
Sometimes, if USLE is calculated but sed_export is not, that is because streams are not defined in those watersheds. sed_export is calculated as the amount of USLE that makes it to a stream, so if streams are not defined sed_export cannot be calculated. This can happen if the Threshold Flow Accumulation value is too large, or it could be a place that is very flat and hard to define streams. So check the stream.tif output as well.
~ Stacie
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Sorry I have no log file now but I have a screenshot of the SDR module result as below image, I’m using 3.7 version. But yesterday I input 10000 instead of 1000 for the input of ‘Threshold Flow Accumulation’ for the SDR input I think that’s why I had this problem
Because of I input 10000 instead of 1000 by mistake for the input of ‘Threshold Flow Accumulation’ for the SDR input and then when I recorrect and run the SDR again I got some values as below, but there is some negative (eg: -1) values and zero for ‘sed export’, ‘sed retention’ and ‘usle total’ for most of watersheds, can that be happen or is there something wrong in my results?
And also I have input the shape file of watersheds that is only include polygons, do I have to clip them with the streams or what should I input as the watershed (vector) ?
Thanks @Nayanathara for the additional information. It still would be useful to see the whole log file, since it shows what the inputs are, and possibly warnings about the inputs that would help us debug.
You’re correct that the shapefile of watersheds should be the whole polygon that drains to a particular point (or points, if using sub-watersheds) on the landscape. They should cover the whole area that you’re modeling.
Did you look at the inputs and intermediate files related to the USLE to see if there were any problems? Look at your input erosivity and erodibility layers, the intermediate files “ls.tif” and “slope.tif”, as well as “rkls.tif”.
~ Stacie
Here is the log file:
InVEST-Sediment-Delivery-Ratio-Model-(SDR)-log-2019-07-09–22_21_44.txt (14.7 KB)
Here is the biophysical table I used:
Biophysical.csv (602 Bytes)
- Can there be negative values for the results of ‘sed_retent’, ‘sed_export’ and ‘usle_tot’ ?
- also I don’t understand that ‘polygon that drains to a particular point’ meaning, should there be pourpoints also in the watershed shapefile?
Thanks for the log file. One thing of note is that you are using an old version of InVEST (3.5), and we recommend updating to the latest version (3.7). I don’t know if the latest version will help with this problem, but maybe.
Your biophysical table values look ok (we don’t use sed_retent any more, so you don’t need to fill that in.)
No, there should not be values of -1 in the watershed result shapefile. Did you look at the input rasters and output streams as suggested? What did you find?
Regarding watersheds: Usually, we are interested in running the model in the watershed that provides water to a point location like a drinking water facility, town or hydropower plant. But no, the model does not require pour points, it just requires a complete watershed so we make sure to capture all of the processes correctly.
~ Stacie