Application of infiltration equations to a catchment with large spatial variability in infiltration

The infiltration equations according to Horton and Philip are applied to 52 double-ring infiltrometer tests performed in a small semiarid catchment in northern Tunisia. Spatial variability in infiltration properties is analysed as regards the coefficients of the two equations. Different geomorphological zones display different infiltration characteristics even if there is large variability within each zone and no clear statistical difference between the zones. Statistical properties of the coefficients of Horton's and Philip's equations describing cumulative infiltration are presented and discussed. The statistical distribution of the coefficients seems to be well approximated by an exponential function.