dynamic landunits: handle methane with changing lake area

**Bill Sacks < sacks@ucar.edu > - 2016-02-16 13:38:10 -0700**
**Bugzilla Id:** [2283](http://bugz.cgd.ucar.edu/show_bug.cgi?id=2283)
**Bugzilla CC:** erik@ucar.edu, oleson@ucar.edu, rfisher@ucar.edu,

The methane code (ch4Mod.F90) implicitly assumes that finundated is 1 for lakes. Thus, if lake area increases, the right thing to do is probably to immediately inundate any land it took over, with code similar to what happens right now when inundated area increases.

Decreases in lake area should be handled appropriately now, but increases in lake area are not. Currently, there is no way for lakes to increase in area, but this will need to be revisited once they can.