A history of TOPMODEL

Abstract. The theory that forms the basis of TOPMODEL (a topography-based hydrological model) was first outlined by Mike Kirkby some 45 years ago. This paper recalls early developments, rejection journal paper, days digital terrain analysis, model calibration and validation, various criticisms simplifying assumptions, relaxation those assumptions in dynamic TOPMODEL. A final section addresses question what might be done now seeking a simple, parametrically parsimonious hillslope small catchment processes if we were starting again.