Solute Travel‐Time Estimates for Tile‐Drained Fields: I. Theory

Abstract

Abstract A model based on papers by D. Kirkham (1949; 1958) is proposed for calculating solute travel times and effluent water quality for tile‐drained soil profiles for cases of ponded and unsaturated surface water input. Variables required for utilization of the model are drain spacing, depth of tile, depth to impermeable zone, soil porosity, and mean discharge rate over the time of study. By using dimensionless variables a characteristic travel‐time parameter is introduced which will represent a system and allow the model calculations to be summarized on a single graph. Simulations are run for cases of miscible displacement, step‐function surface solute input, and periodic surface solute input; differences between ponded and unsaturated leaching are discussed for tile systems.