Water-vapour sorption isotherm and water retention characteristics model

University of Salford conducts:

• The laboratory tests for the WR effects on soil water retention capacity
• Characterization modelling for WR influence on soil hydrological properties

The water retention characteristic model adopted for the WATERAGRI project is developed based on the concept of interfacial physics. There are three different water phases co-exists in unsaturated soils, they are the bulk water in fully occupied pore space, the water vapor in the empty pore space and the water film on the empty pore walls. The model describes and assess the three phases in terms of their respective states using classic physical interfacial theory. It gives out an explicit mathematical expression for the state of the three phases, which establishes a state equation for the soil water retention characteristics at different water contents or pore water saturation, from fully dry to fully wet.

The water retention characteristic model provides the subsurface hydrology modeler an reliable and convenient tool and the end user accurate assessment for the water retainer effect on soil water retention capacity.