3.4 Soil moisture response velocity to rainfall
Two rainfall process was selected (P1 and P9) to clarify the percolation
process of rainfall (Table 4 and Fig. 5). Through the analysis of
different rainfall patterns, we found that Group IV has the longest RT
and the slowest wetting front velocity (WFV, cm/h) within the 1-m
profile. Group II had the shortest RT, approximately 6.4 h, which was
significantly lower than that of the other patterns (p<0.05).
Group I had the slowest WFV of 10 cm but the fastest WFV in the 1-m
profile, which surpassed 6 cm/h (Table 4).
The effect of land-cover change showed that the crop site had the
longest RT and slowest WFV in the 1-m profile at a nonsignificant level
across the five monitoring sites (Table 4). Nevertheless, revegetation
patterns altered this condition, with a smaller RT and a larger WFV.
Specifically, planted shrubs accelerated the WFV by approximately 46.7%
of the surface SM and reduced the RT by approximately 33.7% across the
entire profile compared to the crops. Abandoned grass and planted forest
improved the soil permeability to decrease the ART by approximately
17.4% and 30.8%, respectively, and increased the WFV by approximately
87.0% and 77.9%, respectively, in the 1-m profile compared to the
crops (Supplemental Fig. S3). Hence, revegetation sites decreased the RT
and accelerated the WFV to a great degree.