Help for biopore module in Daisy 1D simulation

[lvxi...@gmail.com]

Hi everyone,

We are setting up the Daisy model (5.21) to see how macropore distributions change the soil hydrology.

We have very detailed measurements of biopore size distributions (diameter and frequency) at different soil depths, together with soil texture and hydraulic parameter estimations, but no field observations of soil water level or tile drain discharge.

Now we run into these problems:

1. The model with biopore module stopped running with error message “../geometry1d.C:109: assertion 'bottom < top' failed in add_soil (error)”. 

And the time when error starts seems to be sensitive to the depth where the biopore ends. Is it due to the numerical instability? How can I solve it?

2. How to parameter biopore module with the measurements we have? Is it possible or necessary to include diameter and frequency at different depths?

3. When running soil profiles without macropore or biopore component, we still see in the soil_water.dll file that there are water exchange between matrix and biopores.

I attached the daisy file for soil input that includes biopore module.

If needed I will send a report describing the Daisy model set up and other input files.

Cheers,

Lan

--------------------------------

Post doc, Ph.D.

 

Department of Bioscience

Faculty of Science and Technology

Aarhus University

Vejlsøvej 25, P.O. Box 314

8600 Silkeborg, Denmark

Tel: +45 871 58407

2.

[Per Abrahamsen]

On Wed, Mar 30, 2016 at 2:56 PM, <lvxi...@gmail.com> wrote:

Now we run into these problems:

1. The model with biopore module stopped running with error message “../geometry1d.C:109: assertion 'bottom < top' failed in add_soil (error)”. 

And the time when error starts seems to be sensitive to the depth where the biopore ends. Is it due to the numerical instability? How can I solve it?

Yes, it is a numerical instability (top > bottom does not imply bottom < top as the code assumed, I hate floating point math). It is fixed in 5.24, get it here: http://daisy.ku.dk/download/windows/

 

2. How to parameter biopore module with the measurements we have? Is it possible or necessary to include diameter and frequency at different depths?

It is important for flow whether the biopores are connected at different depths. So each biopore class has a specific depth where the biopores start, another where they end, and a fixed frequency and diameter between the two depths. To get frequencies that varies with depth, you need multiple biopore classes. 

Note that the most important biopores by far tend to be those that start in in the top soil and go deep, even if they are comparable rare. Shallow biopores, or biopores that start in the subsoil, are far less significant, even if they are much more common.

So measurements of connectivity, either by applying colored water from above, or blowing smoke from below, are the most useful. Some numbers can be found in this (Danish language) report: 

http://mst.dk/service/publikationer/publikationsarkiv/2013/okt/undersoegelse-af-makroporekontinuitet-ved-markdraen-og-effekter-af-direkte-forbundne-makroporer-paa-jords-filterfunktion/

3. When running soil profiles without macropore or biopore component, we still see in the soil_water.dll file that there are water exchange between matrix and biopores.

Did you disable it explicitly? Daisy will by default add biopores if there are more than 5 % clay in the soil.

Use (Tertiary none) to disable.

Regards,

Per