Getting starting cells for parcels implicitly assumes that inlet is located along x=0 coordinate

[amoodie]

Getting starting cells for parcels implicitly assumes that inlet is located along x=0 coordinate.

• pyDeltaRCM/pyDeltaRCM/water_tools.py

  Lines 93 to 94 in edf6927

  	self.qxn.flat[start_indices] += 1
  	self.qyn.flat[start_indices] += 0 # this could be omitted...

• pyDeltaRCM/pyDeltaRCM/sed_tools.py

  Lines 567 to 568 in edf6927

  	px = 0
  	py = start_indices[np_sed]

This has not been an issue so far, but could be better generalized to have self.inlet be a list of flat cell indices, or a nx2 list of x-y indices (probably preferring the former).