Accounting for Infiltration

[Stephan Dreyer]

Good day Tom

I am currently running some models on steep mining landforms, similar to the work which Neeltje did. 

I'm using the latest version (2.0) and barely getting any infiltration. I have done multiple tests with changing the 'm' parameter as well as the evaporation, but I'm still getting very high runoff coefficients (above 90%). To calculate this I'm doing some tests where I add up the total rainfall across the DEM over the simulation time as well as the total outflow from the model. Having tried different 'm' and evaporation parameters, I was wondering what model variable is the primary driver in determining the amount of infiltration? I'm not necessarily trying to get an exact outflow from the model, but the model seems to be overestimating the amount of erosion and reducing the runoff should be one of the ways to reduce that.

The issue is similar to the one described by Raphael here:
TOPMODEL - m parameter (google.com)

I would highly appreciate your feedback and thoughts on this.

Kind regards,

Stephan Dreyer

[Tom Coulthard]

Hi Stephan, 

Rather than look at the m value - I'd try changing the minQ and maxQ values (in the flow tab I think?). These values determine effectively where water is added. If the amount in a cell and those draining into it is greater than the minQ value then it converts that into runoff - thus routed by the flow model. Imagine you have a hillslope. 5 cells from the top of the slope, you have 5 cells each with (say) 0.01 of discharge. to get runoff the area draining into the 5th from top cell you'd need to have a minQ of 0.01*5.. Make minQ larger and runoff (and hence erosion) will start forming further down the slope. This is also linked to the min depth for erosion - so if that is set really low (say 0.001m) and you have a low minQ you will get more runoff and erosion further up slopes. MaxQ simply stops where it happens - so you don't get disproportionaltely too much water added further down the slope. #Hope that helps

Tom 

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From: caesar-...@googlegroups.com <caesar-...@googlegroups.com> on behalf of Stephan Dreyer <stephanu...@gmail.com>
Sent: Tuesday, 23 April 2024, 21:40
To: caesar-lisflood <caesar-...@googlegroups.com>
Subject: Accounting for Infiltration

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