## 3 Results  
### Water Content Changes  
The changes in the water content of different parts of the slopes with different types of mitigation measures are shown in Figure 3, and from the figure we can see that the changes were all quite similar. First, the water content gradually decreased before finally leveling off in all cases. In the early stage of testing, the infiltration rate of rainwater was relatively fast, and the soil water content curves increased rapidly within 15 min after the initial change in water content before stabilizing. In the later stage of the experiment, the slope surfaces reached saturation, and the water content of the soil at different positions and depths stayed at around 60%. In addition, the rainwater infiltration rates of all types of slopes showed were fastest at the upper part of the slope and became slower toward the toe.  
As far as what differences there were in the water content changes with different types of mitigation measures, due to the converging effect of the slope drainage channels, which effectively prevent rainwater from accumulating on the slope surface, the time until rainwater infiltration to deep soil (15 cm) was relatively slow (Figure 3). Additionally, the infiltration rate of slopes with a stepwise drainage channel mitigation measure was slower than with the other two types of slopes, and the time required for the soil to reach saturation was longer as well.  
Regarding local changes, the water content changes in slopes without any mitigation measures were linked to both local and overall failure. When a large-scale block failure occurred at the slope middle, the moisture sensors (5 cm) had obvious fluctuations. The same phenomenon also occurred when the overall slope failed. From Figure 3 we can see that this change was synchronous with the instability of the slope and was a nearly instantaneous change. The response of shallow soil (5 cm) was the most obvious. Shallow  
Figure 3: Water content changes for different slopes at different sites.  
soil tends to become compacted during motion, so any soil water it holds is discharged, and its water content decreases sharply when this happens. Some of the water diffuses to deeper soil, so the water content of the deeper soil then rises slightly.  
When the slope without any mitigation measures failed, the water content of the shallow soil (5 cm) at the upper, middle, and toe of the slope all showed almost instantaneous drops, with the most obvious changes at the upper and middle parts and only a slight change at the toes. The water content of the deeper soil (10 cm, 15 cm) also changed but varied within wide limits. These changes in water content did not appear in the other two types of slopes. The slope with the step-by-step mitigation measure had failures mainly concentrated on the slope surface, and a landslide even occurred in the later stage that had a relatively shallow depth little impact on the deeper soil's water content. Therefore, in the later stage of the experiment, the soil water content of the slope with a declining gradient mitigation did not undergo any sudden changes. The water content of the slope with a stepwise drainage channel mitigation measure also did not undergo any sudden changes, and the water content of the soil at each position increase gradually without sudden uplifts or drops.