“…In the resulting one‐dimensional (1D) Dupuit‐Forchheimer model, the total flow Q [ L 3 /T] out of the river that enters the aquifer on one side of the horizontal well is given by Verruijt (1970), p. 30 Equation 4.10, as: where φ 0 is the river stage, φ w the head in the aquifer at the location of the horizontal well, and B [ L ] the length of the horizontal well being considered. The parameter λ [ L ] is referred to here as the characteristic leakage length defined as (Verruijt 1970): , with B = 1, represents the discharge Q x in the 1D Dupuit‐Forchheimer model for flow to one side of the horizontal well, hence the total discharge σ, per unit length of the horizontal well, is twice that amount: Following the same approach as in Haitjema et al (2010), we compare this total flow () with the inflow into a fictitious stream in a confined aquifer with a bottom resistance c DF (see Figure 1(b)), for which the total flow per unit length of the stream is, see also : Comparing yields a resistance c DF for the horizontal well that includes the resistance to flow through the river bottom and the resistance to horizontal flow in the aquifer: In order to obtain the resistance c ls for the Cauchy boundary condition on the horizontal well, the resistance c DF must be subtracted from c 2 defined by , hence A graph for c 2 is provided on http://www.haitjema.com/transfer/GW2010.zip…”