Hydropedology is a union of hydrology, pedology, and soil physics disciplines with a focus on soil-water interactions. Hydrology is dened as the science that treats the waters of the Earth, their occurrence, circulation and distribution, their chemical and physical properties, and their reaction with their environment, including their relation to living things (NRC, 1991). Pedology is dened as the branch of soil science that integrates and quanti¹es the formation, distribution, morphology, and classi¹cation of soils as natural or anthropogenically modi¹ed entities (Wilding, 2000; Buol et al., 2001; Lin et al., 2006). Soil physics is dened as the study of the physical properties of the soil and the relation of the soil physical properties to the study of the state and transport of matter and energy (Scott, 2000). Although these
denitions are specic and cover the breadth of each discipline, water dynamics, response, and the interactions with the environment are common underlying themes. As a need to unite these disciplines, hydropedology has been dened as an intertwined branch of soil science and hydrology that encompasses multiscale basic and applied research of interactive pedologic and hydrologic processes and their properties in the variably-unsaturated zone (Lin, 2003). More specically, hydropedology focuses on the synergistic integration of pedology and hydrology to enhance the holistic study of soil-water interactions and landscapesoil-hydrology relationships across space and time. Its aim is to understand pedologic controls on hydrologic processes and properties and hydrologic impacts on soil formation, variability, and functions (Figure 35.1; Lin et al., 2008b). Even though hydropedology has its foundation in pedology, soil physics, and hydrology, it is also linked to other bio-and geosciences such as geomorphology, geology, geography, hydrogeology, hydroclimatology, ecohydrology, biology, and other branches of natural sciences (Figure 35.2). In a broader sense, hydropedology seeks to identify feedback mechanisms that allow for a holistic approach to the study and prediction of ecosystem functions.