HYDROPEDOLOGY: A SISTER DISCIPLINE OF HYDROGEOLOGY

Hydrogeoscientists are encountering a new intellectual paradigm that emphasizes connections between the hydrosphere and other components of the earth system. While hydrogeology, hydroclimatology, and ecohydrology are well recognized, an important missing piece of puzzle is hydropedology that focuses on the interface between the hydrosphere and the pedosphere. Hydropedology closes this gap as being an interwoven branch of soil science and hydrology that encompasses multiscale basic and applied research of interactive pedologic and hydrologic processes and their properties in the unsaturated zone. Much like one cannot ignore the role of ground water in performing geologic work, water in the unsaturated zone cannot be ignored in soil formation and dynamic soil systems. A common question hydrogeologists ask when dealing with ground water contamination is “Where, when, how much, and how fast water and contaminants come from the overlying vadose zone?” Because many releases of contaminants to the subsurface occur within or above the vadose zone, including xenobiotic materials applied deliberately (e.g., agricultural chemicals, landfill leachate, or toxic waste dumps) and those released accidentally (e.g., leaking septic tanks, chemical spills, or leaking petroleum tanks), it is imperative that we understand well the impacts of in situ soils on flow and transport through various types and distributions of soils and the deep vadose zone. Hydropedology, in combination with hydrogeology, provides an integrated approach to study water-soil-rock interactions in the earth’s critical zone. Hydropedology takes a holistic view of the landscape, with its root in pedology and a focus on water as a driving force. It characterizes integrated physical, chemical, and biological processes of soil-water interactions across scales, including the mass and energy transport by the water flow, and the interrelationships between soil distributions and hydrologic and geomorphic processes. The interdisciplinary hydropedology emphasizes systems approach, the pattern of its component storages, interfacial fluxes, resident times, path ways, and dynamic changes (including those caused by human activities). Thus, hydropedology is expected to play a unique role in advancing the frontiers of soil science towards a geoscience.