Hywel Thomas is renowned for research into the behaviour of unsaturated soils — those composed of solids, water and air — undergoing processes like excavation or compaction. Hywel has greatly improved our understanding of how liquids and gases move through these soils, such as pollutants seeping from landfill sites, or carbon dioxide being ‘stored’ in coal seams.

Hywel develops and uses sophisticated computer models to predict how chemicals and gases move under a range of conditions of temperature, water pressure and mechanical forces. Addressing issues arising from the environmental impacts of human engineering projects was the stimulus for Hywel’s establishment of the Geoenvironmental Research Centre at Cardiff University.

Hywel contributes his expertise widely, contributing to the United Nations Industrial Development Organization’s work on cleaning up organic pollutants, particularly in West Africa. He is also a consultant to the International Atomic Energy Agency and a member of its network concerned with the geological disposal of high-level nuclear waste.