Abstract
A Porous Plate Tension Lysimeter (PPTL) method was used to measure the vertical water flux through a forest soil where the use of electric power is restricted. The PPTL was installed at the depth of 0.9 m in the upper, middle, and lower slopes of Katsura Headwater Catchment, and soil water flux was measured throughout the year. The vacuum pressure of PPTL was adjusted manually once a week to a target value determined by the matric potential of the adjacent natural soil profile measured by tensiometer. Annual soil water flux was 275, 608, and 601 mm for the upper, middle, and lower slopes, respectively, showing similar fluxes to annual runoff rate in the middle and lower slopes. This result shows that the PPTL method is applicable to measure annual soil water flux.
