| Permeable surface is an important form of rainwater utilization. To study the water penetrating process of the urban permeable surfaces with field test can provide reliable evidences for the scheme design and benefit evaluation of the urban rainwater use. This study reviews the researches of water harvesting effect on the urban permeable surfaces home and abroad, and points out the scope of this research based on the climatic conditions and distribution of permeable surfaces of Dalian. Multi-scale experiments are operated to investigate the time-variant properties of infiltration rate, and the relationship among infiltration rate and rainfall intensity, terrain and other factors in different conditions. The results from this study can be summarized as follows:(1) The infiltration rate has a logarithmic relationship with the rainfall intensity and a negative correlation with the rainfall duration. The experiments indicate that the rainfall intensity plays a leading role, which affects the lodging of plants and the movement of bedload, and also influence the infiltration rate and the runoff rate indirectly. The infiltration rate increases with the growth of the rainfall intensity within a certain range, but a upper limit exists. Under the same rainfall intensity conditions, the longer the rainfall lasts, the smaller the infiltration rate is.(2) The impact of slope on the infiltration rate is affected by the rainfall intensity. When the rainfall intensity is less than 1.51 mm/min, the changes of slope have less effects on the infiltration rate. Nevertheless, when the rainfall intensity is greater than 2.33 mm/min, the distribution of infiltration rate on the grass slope should be divided into three stages. The infiltration rate increases with the slope from 1.1°to 5.7°and 10°to 16.1°, but decreases when the slope ranges from 5.7 to 10°. At the permeable pavement sites, while the rainfall intensity exceeds 2.12 mm/min, the infiltration rate indicates the same trends with the slope in the range of 0-6°. At the Holly sites, the infiltration rate, which is affected by the sump and the canopy obviously, reaches the maximum when the slope is 5°.(3) The effects of spatial scale on theinflitraion rate of the grassland are inconspicuous, but have distinct impacts on the permeable pavements. The runoff speed changes strikingly, which causes the lodging of plants seriously at 1.6-3.2 m on the slope, with the increasing of slope length. But the infiltration rate does not change significantly. At the permeable pavement sites, the longer the slope length is, the greater the runoff fluctuates and the more obvious the spatial scale effect expresses.(4) The soil moisture of topsoil changes rapidly with the different rainfall intensities. But the subsiding process of water in the deep soil is slowly, although the soil moisture is high. A temporary accumulation of water appears at the junction of soil layer, and the soil moisture maintains at the range of 0.5-0.6. The relationship of soil moisture at different positions is: midslope > downslope > upslope. At the downslope, the seeper is formated quickly and the recession process is long. But it is opposite at the upslope.(5) The rainfall simulator and observing system, a flexible and moveable system, shows higher accuracy during the experiments, and can meet the needs of field test in urban.. All the experimental equipments can accomplish the observation of regional rainfall infiltration process rapidly with less damage on primal topography.
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