Numerical Modeling of Moisture Transport Through Evapotranspirative Landfill Cover System

The high infiltration rates in compacted landfill clay cover have largely been attributed to preferential flow paths in the clay layer caused desiccation cracking and animal burrows. In order to remedy the defects, a new evapotranspirative cover is designed. The cover is composed of 1m vegetation layer, 0.5m biointrusion layer and 1m barrier layer. On the basis of considering precipitation and evaporation, a dynamic model is developed for simulating moisture transport in evapotranspirative landfill cover. The results show that the moisture content near the surface is highly sensitive to climate loading, but the effect is significantly attenuated and time lagged along with increasing depth. The moisture from biointrusion layer will transport to vegetation and barrier layer because of capillary break The biointrusion layer can still drain during the rainfall. Parametric analyses are conducted to simulate variations in precipitation rate and precipitation event duration. The experimental data are reasonably agree with model simulation. It is conclusion that the new evapotranspirative cover may substitute the conventional compacted clay cover at arid to semi-arid area.