I am using the InVEST model to assess the water yield of the area, which requires one of the data: “Depth To Root Restricting Layer (Raster)”, which many literature mentions is obtained directly from the properties in the World Soil Database (HWSD) after spatial visualization, but the soil database has only one “REF_DEPTH” and the value size is 100cm or 30cm 。。。。。 I feel that this is obviously not correct.
So, please, from where and by what means should this data be obtained? Thanks!
Hi @littlepencil -
For global data, the User Guide Appendix recommends checking out the Soil and Terrain Database (SOTER) Programme. When you go to that site, you can search for “depth” and see a variety of layers they provide. In the past, we have used SoilGrids250m 2017-03 - Depth to bedrock (R horizon). In general, SoilGrids is a good source of data, but I’ve found that it’s easiest to find all of the available properties by doing this SOTER search, not necessarily using the SoilGrids web browser.
~ Stacie
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Thank you very much for your answer! I followed your suggestion and downloaded the data via the linked address. The value of the data seems to be a bit large (200cm, or 20000mm), and the soil depth in the literature is basically around 1000mm, so I would like to ask if this data can be used?
I have included a screenshot of the soil depth raster data from other papers below for your review
@littlepencil, you can use whatever data is available that seems most correct and appropriate for your study area. Does the SoilGrids data show 200cm depth across your whole area of interest, or is that just the maximum in some areas, but other areas seem more reasonable compared with other studies? How do the patterns of high and low values compare? If the patterns of high and low are similar, and you aren’t comparing against observed data or doing valuation with the results, then perhaps SoilGrids is ok, since you’ll just be working with the relative outputs of the model, and not absolute values. If you are calibrating or doing valuation, then it’s more important to get the soil values correct.
Sometimes it baffles me that there are so many scientific papers showing maps of useful data, that don’t provide those data for public use. Personally, I’d see if any of those paper authors do provide their data (maybe there’s a link in a supplement or something?) If not, perhaps there are other national or global layers you can find.
~ Stacie
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I second Stacie’s advice to focus on the relative values, not absolute, unless comparing against empirical data (for calibration) or attempting valuation. But, 200cm = 2,000mm (not 20,000mm), so the SoilGrids data you downloaded is in fact not that different (same order of magnitude at least) from the maximum depth shown in your screenshot.
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