1.Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resources, 712100, Yangling, Shaanxi,China;
2.Institute of Soil and Water Conservation,Northwest A&F University,712100,Yangling,Shaanxi,China
Abstract：Soil preferential flow causes reduction of soil fertility and contamination of deep soil or groundwater. In order to investigate the effect of initial soil water content on preferential flow, we conducted soil column infiltration experiments in laboratory with man-made macropores in two types of soil at different initial soil water contents. Results are shown as follows. 1) When the initial soil water content
is higher than the critical soil moisture of water repellency, the wetting front migration distance increases with rising initial soil water content for a given soil type, whereas the wetting front migration distance increases with the drop of initial soil water content. For different soil types, the wetting front migration distance deceases with increasing clay particles content. 2) Cumulative infiltration which is affected by both water repellency and soil water storage differs from the change of wetting front migration. The cumulative infiltration of heilu soil in CK group and O-C -30 group (except for the 7.04% moisture content) decreases with the increase of initial moisture content, whereas sand soil from Wei river in CK and O-C-30 group presents two-staged characteristics, i. e. , the cumulative infiltration firstly decreases and then increases with increasing initial water content. 3) The Kostiakov model was used to simulate the cumulative infiltration change over time, and the results showed that the soil infiltration process of preferential flow can be fitted by the Kostiakov model. Our study would provide reference for preferential flow simulation.
2014, Vol. 12 
