Is it possible to obtain Q_river results in Wflow_sbm by distinguishing contributions from both subsurface flow and overland flow components?

[Safa136]

Is it possible, within the Wflow_sbm framework, to derive Q_river results while explicitly separating the contributions of subsurface and overland flow components?

[verseve]

Yes, in wflow you can add lateral.subsurface.to_river [m3/day] and lateral.land.to_river [m3/s] to the TOML file to separate the contribution of subsurface and overland flow to the river flow.

[Safa136]

Thank you for your response. I tried to include it as [output.lateral.subsurface.to_river] and then q = "q_subtoriver" , but it doesn't work. can you elaborate more?

[verseve]

The following settings should work in the TOML file:

[output.lateral.land]
to_river = "q_landtoriver"

[output.lateral.subsurface]
to_river = "q_subtoriver"

[Safa136]

I'm working with a catchment model that has a KGE of 0.7 and generally good performance but tends to underestimate peak flows. I'm puzzled by a discrepancy in flow components: Q_landtoriver is 1.2, Q_subtoriver is 2242.3, and Q_river is 9. Could this suggest a unit/scale issue, or a deeper problem in the model, given its tendency to under-represent peaks?

[verseve]

Please note, that the units are different between Q_subtoriver [m3/day] and Q_landtoriver [m3/s]. These values are for one river cell in the model? Besides these components, there is also inflow from upstream river cell(s).

[Safa136]

Yes, these values are for one river cell in the model.

[verseve]

I expect the underestimation of peak flows (without knowing the actual catchment) is related to model parameters (and not units, these are correct). For example you could check the soilthickness map, the thickness could be too large (in some areas) of your catchment. Or check other (sensitive) parameters like f or ksathorfrac.

[Safa136]

Thank you very much for your prompt and insightful response.

I have been conducting sensitivity analysis on key parameters as discussed in Imhoff et al. (2020b) to assess their impact on my catchment model. The model in question is already calibrated, with optimized values for parameters Ksathorfrac and theta_s. However, you bring my attention to the soilthickness map. I will check it.

I needed the contribution from subsurface and land to river to analyze seasonal variations. I aim to calculate the water balance for different seasons.