Abstract：Combined with a project carried out at Qizishan landfill in Suzhou，the status of leachate in the landfill was investigated；and the saturated hydraulic conductivity and soil-water characteristic curve of municipal solid waste were measured in laboratory. The hydraulic conductivity function was deduced using Campbell¢s equation. Then unsaturated-saturated seepage analyses were carried out to investigate the movement of water in a landfill element，in which the existence of intermediate covers and the efficiency of cutoff ditch were considered. The obtained results show that matric suction in unsaturated zone of the landfill remains between 3 kPa and 6 kPa，with the corresponding volumetric water content between 35% and 40%. This is consistent with the borehole investigation，which shows that the deduced hydraulic conductivity function was applicable to simulate the seepage of leachate in municipal solid waste. The existence of intermediate covers can significantly reduce the infiltration of rainfall into a landfill element. But it becomes an important factor that causes perched leachate as the ineffectiveness of cutoff ditch is concerned. The obtained results are also consistent with those of field investigation.
