Problem with actual and potential evapotranspiration

[mathieupaugam]

Hello everyone,

I'm using Hydrus 2D/3D 2.05 to simulate the capillary barrier effect along the slope of a soil (compost).

I'm using climate data from 2016 to 2022 to have a realistic model, however there is a problem in relation to evapotranspiration.

When summer arrives, there's a lot of evapotranspiration and little precipitation. As a result, the model dries out so much that the water content falls below Qr, causing the calculation to crash. However, the data entered for evapotranspiration correspond to potential evapotranspiration and not actual evapotranspiration, as in reality the model is just dry but retains water at the bottom.

So, is it possible that the calculation considers real evapotranspiration and doesn't crash as soon as the model is dry?

Thank you and I look forward to hearing from you.

Mathieu

[Jirka]

The model does not allow water contents to drop below the residual water content. That’s simply not possible for converting solution.

HYDRUS does not recognize potential or actual evapotranspiration. It always deals only with actual and/or potential evaporation and actual and/or potential transpiration. Thus, it is not really clear what you are referring to. If done properly, Hydrus will reduce potential values to actual values (fluxes) once critical pressure heads (i.e., hCritA or H4) are reached (as documented in hundreds/thousands of published studies.

J.

[mathieupaugam]

Dear Jirka,

Thank you very much for your answer.
I hadn't realized that the Hcrit parameter was used to reduce potential values to actual values once it was reached.
That has solved my problem

Best regards,

Mathieu