SDR model pixels with values in a No data zone

Hello to all,

I ran the SDR model for my country, and have, in the sed_retention.tif raster, areas with No Data that have pixels with values in the middle (see image bellow).

Don’t mind the scale in the legend, it serves only to see if the zero values actually correspond to the streams.The pink areas represent the No Data and the grey is the value 0 (streams).

As you can see, there are isolated pixels in the pink areas (No data). Is this standard or a error?

I know that the model is influenced by the DEM, so I filled the sinks before I using it.

I didn’t get any error while running the model (I’ve ran it before for other projects, so I pre-processed all data correctly this time :smiley:)

Meanwhille, I’ve validated my results comparing them with the EU JRC data for soil erosion, so I don’t think this is significant enough to influence the overall results, but I might be wrong.That’s why I would really appreciate any input you can give me!

Thank you!
Susana

I should mention, that this area, in the image, is an estuary and that I ran the model in InVEST 3.6, in case it helps :slight_smile:

Hi @SusanaMM -

Here are a few things to check. First, look at your other output raster layers - do they all have NoData in the same place, or are some different? Then check is to make sure that none of your input layers have NoData in those areas. It’s common for, say, soil data to be missing where there are water bodies (also glaciers, and some others), and if there’s NoData in any of the inputs there will also be NoData in the outputs.

I also usually look at the streams.tif output layer. 3.6 is a rather old version of InVEST, and I don’t recall whether it produced 0s or NoData where there are streams. Looking at your output, perhaps there are 0s in streams, so it isn’t just that all of the streams have a NoData value.

And I recommend trying the latest version of InVEST, for several reasons. There have been changes and a lot of bug fixes since 3.6, and it now has a “sediment deposition” output that you might be interested in, since you’re looking at sediment retention. The sed_retention.tif output by SDR 3.6 does not show the actual amount of soil retained by a pixel, it’s only intended to provide a relative ranking, showing what would happen if the current vegetation was turned into bare soil. InVEST 3.8 added “soil deposition”, which actually quantifies where and how much soil gets deposited as it moves downhill toward a stream.

~ Stacie

1 Like

Hi @swolny,

Sorry for the very late reply.

You are right, the problem is the oficial K-factor map from JRC presents this kind of pixels, therefore the outputs will be like this also.

The recent version of InVEST seems interesting with the sed_deposition, I will try it for sure.

Thank you so much for your help :slight_smile:

Susana