The saturated-unsaturated seepage test system is established in order to study seepage under water level sudden raise and rapid drawdown. The matric suction in unsaturated zone within the dam model is tested. During the test
the atmospheric temperature and humidity of the laboratory are also recorded at the same time. The matric suction evolution under the changing water lever and its influencing factors are discussed. The results show that the matric suction in the model is not only related to the water level changes and the position of measuring points
but also affected by the impact of the atmospheric temperature
humidity
evaporation and other external environmental factors. The dominant factor between the changes of water level and evaporation
determines the matric suction evolution in the unsaturated zone.