Question

How to calculate residence time in a lake? I believe it differs from water age.

Answer 1

Residence time is generally defined as a bulk number given by the volume of the lake divided by the total inflow rate.

The modelled water age allows you to look at the actual time the water has been in the lake either at the output or in other locations.  This allows you to look at short-circuiting and at areas of stagnation.

Chris

Comments

I get the lowest water age, at the deepest part of the study pond close by the inlet, far from the outlet. Is that possible?

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Yes, this makes sense.  The water coming in at the inlet will come in with age 0 and will 'age' as it moves towards the outlet