Infiltration rate and hydraulic conductivity measured with rain simulator and disc permeameter on sloping arid land

The objective of the study was to examine relationships between steady infiltration rates and hydraulic conductivity obtained with drip infiltrometer and disc permeameter on moderately to strongly sloping land. The disc permeameter is generally used for measurements on horizontal or slightly sloping surfaces but is easier to handle in the field than the drip infiltrometer. At two sites on natural prairie in Central Chile, a portable drip infiltrometer was used to measure infiltration rate and simulate rain, including the impact of falling drops, using two strategies: (1) DIH-starting with a high application rate and decreasing it until a minimal application rate that generated steady runoff was obtained, and, (2) DIL-starting with a low rate and increasing it until steady infiltration rate that did not increase was ensured. In parallel, a disc permeameter was used to determine infiltration rate (PI) and hydraulic conductivity (K) at different supply water pressure heads (psi). Infiltration rates obtained with the DIL strategy were on average only 46% of those of DIH. Application intensity, particularly at the start of events, was crucial in the impact on structural changes in the soil surface. The drip infiltrometer DIH was larger than or equal to the disc permeameter PI and K at psi = -20 mm. The DIL corresponded with PI at psi = -40 mm and -60 mm and K at psi = -30 mm. Disc permeameter was shown to be a useful tool as an alternative to drip infiltrometer to determine infiltration rates even on moderately to strongly sloping land, if measurements with the former are carried out at some predefined psi as identified in this article.