Various cover systems have been designed for landfill sites in order to minimize infiltration （percolation） into the underlying waste. This study evaluated the soil water balance performance of evapotranspiration covers （ET covers） and simulated percolation in the systems using the active region model （ARM）. Experiments were conducted to measure water flow processes and water balance components in a bare soil cover and different ET covers. Results showed that vegetation played a critical role in controlling the water balance of the ET covers. In soil profiles of 60-cm depth with and without vegetation cover, the maximum soil water storage capacities were 97.2 mm and 62.8 mm, respectively. The percolation amount in the bare soil was 2.1 times that in the vegetation-covered soil. The ARM simulated percolation more accurately than the continuum model because it considered preferential flow. Numerical simulation results also indicated that using the ET cover system was an effective way of removing water through evanotransoiration, thus reducing nercolation.
