Document location of withdrawal code in HSPF and hsp2

[rburghol]

• Where/when are RCHRES Special actions called in old model:
  • Reach special actions, in old model called at beginning of timestep in SUBROUTINE RCHRES, line 519 in HRCH.for
  • Where do WDM withdrawals get pulled? Subroutine HYDR
  • See extensive list of functions in RESPEC repo: SPEC-ACTIONS in hsp2 respec/HSPsquared#90
• Where/how are withdrawals subtracted in new model?
  • subroutine _hydr_ : def _hydr_(ui, ts, COLIND, OUTDGT, rowsFT, funct, Olabels, OVOLlabels):
  • what role does irexit code play in new code (FTABLEs have exits, maybe for releases or withdrawals?)
  • OUTDGT is where withdrawal data is inputted from WDMs in old model, and the _hydr_ function in new model takes OUTDGT as argument: ef _hydr_(ui, ts, COLIND, OUTDGT, rowsFT, funct, Olabels, OVOLlabels):
  • calls to function called demand() set variables rod1,od1[:], see: rod1,od1[:] = demand(v1, rowsFT[indx, :], funct, nexits, delts, convf, colind, outdgt) in lines 277, 279, 329, 337, etc
  • Find variables OUTDGT https://github.com/respec/FORTRAN/search?p=2&q=OUTDGT
• Where/When should RCHRES Special actions called in new model?:
  • Propose: New model corresponding location is before line 268 just before start of "irexit" code.