Les' research interests are based around the areas of Sediment generation and sediment yield, Erosion modelling Tracers for determining sediment sources, Hillslope and riparian hydrology, Soil and slope stratigraphy, Wetland ecology and Soil and vegetation history.

He is a a member of the New Zealand Society of Soil Science, the New Zealand Hydrological Society, the New Zealand Geological Society and the New Zealand Association of Resource Management.