code: def stout_w_per_flow(self, z):
          
          w_per_flow = 2 / ((2 * pc.gravity * z) ** (1 / 2) *
                            con.VC_ORIFICE_RATIO * np.pi * self.hl)
          return w_per_flow.to_base_units()
docs: Return the width of a Stout weir at elevation z. More info
          here. <https://confluence.cornell.edu/display/AGUACLARA/
          LFOM+sutro+weir+research>