Hello,

I have measured outflow from the base of a soil column and would like to use this as a cumulative boundary flux in my objective function. The soil column is 250 cm long and is discretized into 150 nodes (i.e. node #150 is located at 250 cm). The column has an atmospheric surface boundary condition and a constant head bottom condition (i.e. the water table at h=0). There are 52 days in the simulation. I have input the data for the inverse solution as follows:

X: 52 (since the measured outflow is cumulative for the entire simulation)

Y: -3.0 (since I have measured 3 cm of outflow, therefore the entry is negative)

Type: 0 (cumulative boundary flux)

Position: 150 (since this flux occurs across the bottom of the soil column, at node 150

I am getting an error that says: "The fourth column of the record must be smaller than or equal to 2 oar larger than or equal to 1".

The Help document suggests there is some type of special code I should be inputting instead of the node position - but I can't find this information anywhere. If anyone can help me out I would much appreciate it!

Cheers,

Alexandra

## Cumulative boundary flux for objective function

### Re: Cumulative boundary flux for objective function

Position = 1 for surface and = 2 for bottom. You should see that in the couple of examples (onestep, multistep, etc). J.