Richard Mead's Introduction to using the internet for this type of research. The 'unsaturated-soil' list is a discussion list for researchers studying the engineering behaviour of unsaturated soils. Technical Committee No. 6 of the International Society of Soil Mechanics and Geotechnical Engineering which deals with Unsaturated Soils.
Archives are available on the list webpage.
The motivation for GSWP stems from the paradox that soil wetness is an important component of the global energy and water balance, but it is unknown over most of the globe. In particular, see the report explaining the problem of establishing hydrologically important quantities from remote sensing or existing land-based observational networks.