How to apply different 12-month LAI data for every year and which parameters/variables adjust the baseflow and peak width?

[Martin20494]

Hi team,

At the moment, I am using the same 12-month LAI dataset for all years. I was wondering whether there is an alternative approach that would allow me to use year-specific 12-month LAI datasets (i.e., a different annual LAI cycle for each year), rather than applying the same one across all years.

In addition, do you know which parameters or variables can be used to adjust the baseflow and peak width? At present, my simulated baseflow is very low. I have come across this discussion, but the parameters listed there appear to mainly influence the peak magnitude, rather than the baseflow or the width of the hydrograph peak.

I am using Wflow v0.8.1. Please let me know if you need further information.

Thank you very much,

Martin Nguyen

[JoostBuitink]

Dear Martin,

Thanks for your message! Regarding the LAI question, it might be good to clarify that by default a (monthly) climatological average LAI pattern is expect, but you might be already aware of this. Your question still valid as LAI value can change over longer time periods due to land cover changes such as de- or afforestation. You have two approaches to include this in your simulation: either (1) include the LAI as a forcing parameter, or (2) prepare different sets of monthly LAI maps.

For option 1, you will need to prepare LAI maps for every model timestep, similar to the precipitation/temperature/PET maps. This would require quite some data and storage, and might not be the most feasible solution
For option 2, you will need to prepare a different set of monthly LAI for (e.g.) each decade that you are planning to simulate. To use those maps, you need to split up your simulation period into each decade. When the first decade has completed, you stop the simulation, update the TOML file to use a new LAI maps, start a new simulation that uses the states from the previous one; and continue until you have completed the entire simulation period.

For the parameters, the suggestions made in the linked discussion are best parameters to start adjusting, as most parameters mentioned there (specifically the ksathorfrac and also to some degree the f parameters) are affecting both peak and base flows. Hopefully varying some of these parameters will give a result that is more in line with the discharge observations.

[AquaPore]

Thanks for taking your time for answering these questions, which I had.

Joseph A.P. POLLACCO

[Martin20494]

Dear @JoostBuitink,

Thank you very much for your response. I really appreciate your guidance.

Regarding the LAI data, I will follow your option 2.

For the parameters, I have adjusted three of them, and all impacted only the peak magnitude, as follows:

• KsatHorFrac: reducing from 100 to 50
• InfiltCapSoil: reducing from 600 to 350
• f map: multiplied by 5

Unfortunately, these adjustments do not affect the baseflow or the peak width (see attached figure). Could you please advise me on other options to influence these aspects?

Thank you very much for your help.

Martin Nguyen