# Question about ERA5 volumetric soil water data

**URL:** <https://forum.ecmwf.int/t/question-about-era5-volumetric-soil-water-data/1632>\
**Category:** C3S - Datasets and Usage\
**Tags:** c3s, global\_reanalysis, era5\
**Created:** [13 December 2021 18:49 UTC](https://forum.ecmwf.int/t/question-about-era5-volumetric-soil-water-data/1632 "2021-12-13T18:49:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Tian\_Gan](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/t/b9bd4f/32.png) [@Tian\_Gan](https://forum.ecmwf.int/u/Tian_Gan)\
**Post date:** [13 December 2021 18:49 UTC](https://forum.ecmwf.int/t/question-about-era5-volumetric-soil-water-data/1632/1 "2021-12-13T18:49:15Z")

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Hello,

I have a question about the volumetric soil water data from ERA5 reanalysis datasets . I wonder if someone could help answer whether the volumetric soil water parameter from ERA5 is calculated as water volume / total volume or water volume / (total volume \* porosity).&nbsp;

The reason I want to know is that I hope to use ERA5 volumetric soil water data to calculate the water table depth at each soil layer. I am not sure which function below should be the correct one if I use ERA5 volumetric soil water data:&nbsp;

1) water\_table\_depth = soil\_layer\_depth \* volumetric\_soil\_water&nbsp;

2) water\_table\_depth = soil\_layer\_depth \* volumetric\_soil\_water / porosity

Thank you!

Tian