[Field test and evaluation of landfill performance and structure with evapotranspiration cover]

Water balance performance of an evapotranspiration landfill was studied, considering vegetation structures, soil textile, and soil cover thickness. Results of six experiments showed that the transpiration process played an importance role in controlling water balance in the ET cover system. A nonlinear relationship was established between the transpiration amount and vegetation leaf area index. The evapotranspiration amount was 3.3 to 4.5 times as that of evaporation in the bare soil. In a 60 cm soil profile, the soil water storage capacities were 97.2 mm and 62.8 mm with and without a vegetation cover, respectively. Precipitation infiltration behaved preferentially and heterogeneously, and the preferential flow was the major contribution to percolation. The ratios between maximum and average infiltration depths were 3.65, 1.77, and 1.40, respectively, for 20 mm, 40 mm, and 60 mm of precipitation. Therefore, besides soil textile, soil cover thickness, and the initial water content, precipitation amount was an essential factor affecting the water storage capacity. Numerical simulated results indicated that using a sandy loam as the cover soil was more effective in removing water through evapotranspiration and reducing percolation than using a clay soil.