I model the rainfall recharge using a 45m column.Firstly i set the initial head as -100cm uniformly for free drainage and all the model works properly. Then i switch the lower bc to deep drainage, which i think will be more real. In that case the bottom pressure head, h>0,(always merge below the table, right?) so i changed: from top to the water table level, h from -100cm to 0; from water table to the bottom, h increase from 0 to 800cm (estimated bottom is at 8m below the table), then there is a convergence problem, it came out half way during model run. so where may be the problem:
- input daily rainfall at some point may vary too much, so it cannot converge, possible? so i increased time tolerence(up to 0.1) and pressure tolerence value(up to 10) then run, it skipped some but later still failed to converge.
- will A,B value in deep drainage equation affect it? if yes how to change?
- does my the initial h set properly at the graphic editor?
- I set GWL0L=0m, make sense?
- Min time step i tried: 1e-5, 1e-6, 1e-7. None converges.
- I increased node number to nearly 1000, while gets denser at the two ends. Still doesn’t work.
Any help will be apprecited.
I didn’t find the right solution from the Internet.
Collaboration Solution Example