Transport of water, energy, and substances (plant nutrients, chemicals, salts) in shallow aquifers, soils, vegetation, and the atmosphere are strongly coupled and controlled by transfers between these different compartments. Evapotranspiration (ET) influences the energy balance of terrestrial surfaces and drives the hydrological cycle and plant physiological function. Despite the centrality of ET for hydrological and climate models, the calculation of ET for certain conditions and its prediction over time remains a challenge due to complex interactions between external boundary conditions (radiation, temperature, humidity, air velocity) and surface properties that with internal transport properties of plants and soil determine the magnitudes and dynamics of fluxes.
This session brings together contributions that present new experimental methods for investigating interactions and transfers between groundwater-soil-vegetation-atmosphere compartments, that present model approaches to simulate these interactions, and that combine monitoring and modelling approaches to improve the prediction of these transfer processes, and theoretical and experimental studies of the land-atmosphere interface with special emphasis on controls by land transport processes on exchange rates.

This session also honours the wide-ranging soil physics contributions Peter Raats made throughout his career. His papers have been predominantly theoretical and often combined deep insight in fundamental processes with mathematical prowess, invariably backed up by a formidable overview of the relevant literature. A very incomplete sampling of topics he covered illustrates the range of his work: Mathematical analysis of flows in drained fields, multidimensional unsaturated flows, the mechanics of swelling and shrinking soils, and water flow in such soils, a generalized soil water retention curve, root water uptake, preferential flow and wetting front instability. Apart from their obvious mathematical rigour, Peter's papers often offered original viewpoints and thought-provoking lines of thought, thereby imparting knowledge but also inspiration to those who studied them carefully.