Dynamic variation of soil moisture and temperature under infiltration of low-temperature water

An experimental study was conducted in an indoor soil tank, to examine low-temperature infiltration and movement through unsaturated soil in topsoil layer of riparian zone. Low-temperature water infiltration tests were carried out at three different heads in the filling fine sand. Infiltration process, moisture and temperature fields were continuously monitored and analyzed to study the impacts of the water head, the infiltration parameters, and moisture and temperature fields. Results showed that the higher the infiltration head, the greater is the vertical (horizontal) migration distance of the wetting front. The migration velocity of the vertical wetting front also gradually decreased with increasing infiltration time, and becoming more and more stability at the end. Infiltration rater had the larger fluctuations at the head of 5 cm and the settling time is greater than the head of 25 cm and 45 cm. The higher the infiltration head, the faster is the decreasing rate of average temperature before the temperature fields could go into a relatively steady status. At the head of 25 cm, infiltration of the low temperature water basically reached steady status after 420 min and the head of 45 cm is after 240 min.