Field observations of soil hydraulic properties were conducted on 11 plots, including 1 virgin forest plot and 10 plots at different operational periods of the IFMS (Fig. 2). The IR or infiltrability tends to be high during the early stages of ponded infiltration when the pressure gradient dominates over gravitational force, but gradually decreases to a constant rate when gravitation is the only force acting on the water; this is called the steady-state infiltrability [12, 31]. The maximum rate at which water can enter the soil surface is termed the infiltration capacity (fm). The infiltration capacity diminishes over time in response to several factors that affect the downward movement of the wetting front [32].