Blue-green infrastructure is becoming an integrated part of city design that can help to mitigate
the environmental impacts of urbanization. Constructed soils along with plants are key
components of blue-green infrastructure such as green roofs and infiltration swales. The aim of
this project is to elucidate through invasive and noninvasive experimental methods the hydraulic
functioning of multi-layered soils. Constructed soil systems comprising two or more layers of
media with contrasting physical properties may provide better performance in terms of
evapotranspiration loss, infiltration capacity, contaminant removal, and support for plants, than
do non-layered soils. Interfaces between layers can induce effects like capillary barrier, finger
flow and air entrapment that are well understood as individual phenomena in natural soils but
have not yet been studied in constructed soils. Recently developed approaches to modelling
fluxes of water and solutes in the soil-plant-atmosphere continuum in natural settings will be
extended to multi-layered constructed soils.