Determination of hydraulic behavior of hillsides with a hillslope infiltrometer

Watersheds, in many parts of the world, consist of sloping soils with a dense subsoil at shallow depth. Very few measurement techniques exist for realistically determining hydraulic properties in situ on these hillside soils. A hillslope infiltrometer, open at the bottom, top, and downhill sides, was developed that can measure the vertical saturated conductivity of the horizon sequence and lateral hydraulic conductivity of the horizon most conductive to water. The infiltrometer was tested on the steeply sloping soils in Honduras. Increasing rainfall intensities were applied and lateral flow rate was measured in several troughs at the downslope end of the hillslope infiltrometer. Vertical infiltration rates for the horizon sequence and lateral conductivity were calculated at each rainfall rate after steady state conditions were established. The hillslope infiltrometer proved useful in the characterization of subsurface flow on the steep slopes in Honduras.