Topographic Wetness Index - Covariate Calculation

NIEHS / PrestoGP

Penalized Regression on Spatiotemporal Outcomes using Gaussian Processes a.k.a. PrestoGP

https://niehs.github.io/PrestoGP/

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Topographic Wetness Index - Covariate Calculation #1

Open kyle-messier opened 11 months ago

kyle-messier commented 11 months ago

https://zenodo.org/records/4460354

30m level TWI - This variable is often an important predictor in groundwater variables.

sigmafelix commented 11 months ago

@Spatiotemporal-Exposures-and-Toxicology

Thank you for letting me know. I tried to download the file through the link, but the download failed five times with different approaches (download from browser, local wget, geo cluster wget, run R download.file). I am trying to download it for today and share if I get any updates.

By the way, which statistic do we want to compute for TWI? I think TWI is not additive, so I am wondering if we need to extract at points or the mean in HUC or point buffers. I guess extracting values at points would make sense as TWI already reflected the stream flow and connectedness.

kyle-messier commented 11 months ago

@sigmafelix There are other versions of pre-calculated TWI we can try. The EPA data you found has one available as a map service: https://www.arcgis.com/apps/mapviewer/index.html?url=https://geoplatform.epa.gov/arcgis/rest/services/NEF/WetnessIndex/MapServer&source=sd https://geoplatform.epa.gov/arcgis/rest/services/NEF/WetnessIndex/MapServer

USGS has one or more too: https://www.sciencebase.gov/catalog/item/56f97be4e4b0a6037df06b70

I think a point extraction or average in HUC are both valid and sufficient.

sigmafelix commented 11 months ago

@Spatiotemporal-Exposures-and-Toxicology Thank you for the information for the alternative data sources. I found that these data have different information on wetness. According to EPA WSIO description (i.e., the 75th entry), EPA uses flow accumulation and slope to calculate wetness and the result includes the quintiles of the probability of wetness. USGS data summarized topographic wetness index from upstream conditions at NHDPlus catchment area. The dataset we initially considered is based on topographic wetness index (range: -3 to 29), which is based on multiple direction algorithm where multiple neighboring cells can get the portion of area of the upstream cells. For the time being, I succeeded downloading the data and copied it to the DDN folder.

Cf.

TWI (Zenodo)

EPA

sigmafelix commented 11 months ago

Calculation at AZO coordinates is completed.