The basic principles are derived of steady momentum dissipation during laminar boundary-layer flow in macroporous soils. The principles lead to a flux law and to geometrical measures of the flow paths. The theory of kinematic waves evolves, and the shock fronts are routed with the method of characteristics. The approach is applied to TDR soil moisture readings at depths 0.15, 0.35 and 0.55 m in a soil under meadow during an infiltration experiment (rate and duration of sprinkling were 2.78 x 10−5m s−1and 4500 s, respectively). Momentum dissipation during flow within the soil profile is independent of momentum added to the soil surface by sprinkling. Specific momentum dissipation per unit depth in the soil profile was about 0.02 kg m−2s−1, with a tendency to increase with depth.