| Based on slope vegetation, this paper chose the slope of different vegetation types as the research object to study the soil infiltration law and the moisture migration characteristics of the slope under different natural rainfall intensity. In addition, indoor artificial rainfall tests were used to research rainfall interception performance of African jasmine and Zoysia tenuifolia. In conclusion, this paper explored the hydrological effect of slope vegetation on Hainan Island soil slopes from two aspects.The author set up a slope whose gradient was about 15°in the field, afterwards divided it into three slopes of equal area, and then planted Africa jasmine and Zoysia tenuifolia on two of them separately, while set another one as bare soil slope for comparing, after that buried moisture sensor in different position of three slopes to monitor the moisture content of each measuring point under different rainfall intensities, the results showed that:The initial moisture content of each measuring point in the same slope were different at the beginning of every rain, neither did each measuring point of the same position in different slopes.The change of moisture content of each measuring point at 20cm depth of African jasmine slope and Zoysia tenuifolia slope were regular under each rainfall and 24 hours later with time passing by. The changing trend was manifested as: at first the moisture content increased to the peak quickly with time increasing, then fluctuated near the peak after a period of time, reduced continuously after that, and the decreasing trend became more and more slow.During the rain, the time to change obviously and reach the peak of the moisture content of the measure point in the center of African jasmine slope and Zoysia tenuifolia slope at 20 cm depth was obviously much earlier than that of the measure point at the top and the bottom in the same slope, besides, the variable quantity of the moisture content was also far greater than them. It was concluded that this phenomenon may be due to the root-soil interstice which was in the measuring range of the measuring point. So the water took them as channels to form the preferential flow and moved preferentially and rapidly in the soil.The values of moisture content in the bare soil slope had not changed obviously under three different rainfall intensities. It was speculated that: firstly, most of the rainwater formed the surface runoff and flowed along the slope, so the rainfall which seeped into the ground was less; secondly, the red clay band on the bare soil slope was so tight that the permeability coefficient was minimal, and so was the permeation quantity. As a result, the moisture content of each measuring point had no obvious change.The research by introducing the concept of influence depth showed that when the daily rainfall was not more than 12.6mm, the influence depth of rainfall infiltration on the moisture content of slope soil was less than 40cm.After the outdoor experiments, the author improved the artificial rainfall simulator to determine the interception of African jasmine and Zoysia tenuifolia under different rainfall amount and different rainfall intensities by simulating rainfall, the main conclusions were as follows:When the rainfall intensity was constant, the interception of African jasmine and Zoysia tenuifolia abidingly increased with the enhancing of rainfall amount, then gradually stabilized after reaching the peak, and tended to a stable value eventually, the increasing range decreased gradually.When the rainfall amount was constant, the interception of African jasmine and Zoysia tenuifolia abidingly decreased with the increase of rainfall intensity, and the increasing range also decreased gradually. |
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