Nodes of different colours represent the following:
Solid arrows point from a submodule to the (sub)module which it is
descended from. Dashed arrows point from a module or program unit to
modules which it uses.
Where possible, edges connecting nodes are
given different colours to make them easier to distinguish in
large graphs.
this subroutine checks manual continuous irrigation (irrp) setting for wetland/paddy in the management.sch
apply irrigation depth based on target ponding depth and the current depth