Moisture Migration of Landfill Ecological Sludge Evapotranspiration Cover System
Wuhan Polytechnic University, Wuhan, 430023, China
Compacted clay landfill closure cover system cracked by the impacts of climate, and its engineering properties significantly reduced. An ecological sludge evapotranspiration cover system was proposed, made of a hydrophobic layer (3cm), nutritional layer (30cm), and impermeable layer (15cm). One dimensional mathematical model of moisture migration in evapotranspiration cover system was established. The moisture variation of sludge evapotranspiration cover system within a year was simulated with 1976 precipitation, evaporation and transpiration as boundary conditions in Dalian. The results showed that moisture of hydrophobic layer was affected more significant by precipitation and evaporation. The impact was relatively small in nutritional substrate layer. The moisture showed the significant peak hysteresis with the increasing of soil depth. The affected was weak in the impermeable cover layer, and only fluctuations emerged at the 7cm upper part. This new cover system was fully capable to withstand nearly 48 years since the biggest impact of heavy rainfall in Dalian. Precipitation intensity, duration of precipitation and permeability and thickness changes of nutritional substrate layer had weak influence to water supply of the impermeable cover layer.
Keywords: ecological sludge; landfill; evapotranspiration cover system; moisture transport
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