Can we distinguish Richards' and Boussinesq's equations for hillslopes?: The Coweeta experiment revisited

Previous analyses of subsurface flow down sloping, shallow soil hillsides a re further simplified. Surprisingly, whether the starting point is Richards ' or Boussinesq's equation, the derived analytical expressions for cumulati ve outflow are identical, and they agree very well with experimental result s from the Coweeta Hydrological Laboratory [Hewlett ann Hibbert, 1963]. We show that Boussinesq's model can be improved from a theoretical point of vi ew at a very small cost. We also solved Boussinesq's equation numerically. However, this improved model did not fit the experimental data any better, while the numerical solution only showed a marginal agreement with the obse rved data.