Supplementary material to “Advancing the Emerging Field of Hydropedology”

Henry Lin and Kamini Singha, Pennsylvania State University, University Park

David Chittleborough, University of Adelaide, Adelaide, South Australia, Australia

Hans-Joerg Vogel, Helmholtz Centre for Environmental Research (UFZ), Halle, Germany

Sacha Mooney, University of Nottingham, Nottingham, UK

Citation:

Lin, H., K. Singha, D. Chittleborough, H.-J. Vogel, and S. Mooney (2008), Advancing the emerging field of hydropedology, Eos Trans. AGU, 89(48), 490.

[Full Article (pdf)]

Inaugural International Conference on Hydropedology Offers Outlooks on Synergistic Studies of Multi-Scale Soil and Water Processes

Both soil science and hydrology are at a critical threshold of advancing frontiers and exploring breakthroughs. Synergies are expected by bridging classical pedology with soil physics, hydrology, geomorphology, and other related bio- and geosciences to address complex soil and water interactions across spatial and temporal scales. Holistic study of the earth's Critical Zone (i.e., the critical interface between the surficial solid earth and its fluid envelopes, which ranges from the top of the vegetation to the bottom of aquifers) demands an interdisciplinary systems approach to tackle a wide array of environmental, ecological, agricultural, geological, and natural resource issues that are of high societal importance. In this spirit, and with a goal of promoting integration between disparate fields and fostering new collaboration, the 1^st International Conference on Hydropedology was held at the Pennsylvania State University in July 28-31, 2008. The conference theme was "Water and Soil: Key to Sustaining the Earth's Critical Zone." The International Union of Soil Sciences (IUSS) Working Group on Hydropedology organized this meeting with main sponsorships from the USDA National Research Initiative and Penn State.

This was a focused interdisciplinary conference with 145 participants from over 20 countries (covering all continents except Antarctica). A large number of leading scientists from diverse fields (pedology, soil physics, and other branches of soil science; watershed hydrology, ecohydrology, hydrogeology, remote sensing hydrology, and other subdisciplines of hydrology; geomorphology, geochemistry, microbial ecology, botany, agricultural engineering, and other related bio- and geosciences) participated and presented their perspectives on various issues related to hydropedology. The three-day program, plus the fourth day field trip, gave the participants opportunities to analyze what has been accomplished in hydropedology and to discuss ways of advancing this emerging field and collaborations across scientific disciplines. While multiple interpretations of the term "hydropedology" appeared during the conference, it became clear that the main goal of hydropedology is to understand interactive hydrologic and pedologic processes across scales and their impacts on biogeochemical cycling and ecological functioning. Two fundamental questions at the "heart" of hydropedology are:

How do soil architecture and the distribution of soils over the landscape exert a first- order control on hydrologic processes and the associated biogeochemical and ecological dynamics across spatio-temporal scales in the surface and shallow subsurface?
How does landscape water, and the associated transport of energy, chemicals and sediment by flowing water, influence soil genesis, evolution, variability, and functions?

Through presentations and discussion, it was evident that hydropedology emphasizes in situ soils in the landscape, where distinct pedogenic features (e.g., peds, horizons, and catenae), environmental variables (e.g., climate, landforms, and organisms), and anthropogenic impacts (e.g., land use and management) interact, thereby determining landscape water availability and quality. The conference participants suggested that, whereas the focus of hydropedology must be clear, its boundary with adjacent disciplines is better left "fuzzy" in order to avoid building walls that would block interdisciplinary collaborations.

The conference began with five invited keynote presentations on the "big picture" pertinent to hydropedology, including 1) Frontiers of Mars Exploration – "Follow the Water" by Raymond Arvidson (Washington University in Saint Louis), 2) The Dependence of Watershed Processes on the Evolution of the Critical Zone by William Dietrich (UC Berkeley), 3) Streamflow Generation Theory in the Headwaters: a Hydropedology Approach by Jeffery McDonnell (Oregon State University), 4) Hydropedology as a Foundation for Environmental Policy and Regulations by Johan Bouma (Wageningen University), and 5) Digital Soil Mapping and Hydropedology: Putting the h into scorpan by Alex McBratney (University of Sydney). The subsequent presentations were grouped into the following five sessions spread over two and half days: 1) Emerging concepts and theories in soil science, hydrology, and related disciplines; 2) Frontiers of integrated and multiscale models of soils and hydrologic systems; 3) Advanced monitoring, sensing, mapping, and visualization of the subsurface; 4) Integrated studies of the earth’s Critical Zone and its relations to hydropedology; and 5) Cutting-edge applications and innovative education/outreach related to hydropedology. Poster sessions, breakout discussions, and evening featured presentations were also included in the conference program. Some research priorities highlighted during the conference include:

¾ Potential conceptual breakthroughs in hillslope/catchment hydrology, including subsurface excess theory, preferential flow networks, and dynamic boundary conditions
¾ Quantification of soil architecture, landscape patterns, and their functional manifestations as a new basis for landscape-soil-hydrology research across scales, which should be explicitly considered for scalable processes and tools
¾ Investigation of the continuous field assumption vs. the discrete object approach to incorporate flow and transport pathways, patterns, residence times, and networks into models
¾ Coupling hydropedology and biogeochemistry to identify "hot spots" and "hot moments" of chemical reaction, nutrient cycling, and microbial activity as triggered by soil hydrologic conditions and limited by transport and pathways in the field
¾ Joining of pedology (with field expertise and without Soil Taxonomy luggage) with soil physics/hydrology (quantitative, process-orientated but without abstract excesses) ¾ Technology advancements in new tools and sensors, sensor/monitoring networks, and spatially/temporally continuous imaging/monitoring of the subsurface ¾ Development of a common platform to share data, information, and model with interoperable format

The field trip included a show-and-tell visit to the Shale Hills Critical Zone Observatory (CZO), one of the first three CZOs established in the U.S. by NSF. Other field destinations included Kepler Farm (including a demonstration of geophysical tools and precision agriculture practices in relation to hydropedology), Penn State's long-operating "Living Filter" (showcasing the use of natural soils for filtering treated wastewater), and pyrite remediation at the adjacent I99 construction site (illustrating the impacts of exposed pyrite on water quality). "The kinds of initial steps and results shown at the Shale Hills CZO and the synergy amongst the CZO PIs, students and collaborators are the reasons for optimism on the future of CZOs," commented Dr. Jun Abrajano, Head of Surface Earth Processes Section of NSF, who attended the conference.

An additional objective of the conference was to charter a roadmap for international collaboration to advance the frontiers of hydropedology and its contributions to the larger scope of Critical Zone science. A new initiative to foster a global alliance for Monitoring, Mapping, and Modeling of the Critical Zone (called the "3M" initiative) was proposed by the Hydropedology Working Group. This initiative follows the example of the Mauna Loa Observatory that first alerted the world to the anthropogenic contribution to the "greenhouse effect" and global warming. The famous Keeling Curve" of long-term CO₂ data demonstrated the value of continuous recording of a seemingly routine atmospheric measurement, which turned out to be a vital sign of the earth's changing climate. The discovery of "acid rain" in North America through long-term monitoring at Hubbard Brook is another role model for the proposed initiative — which calls for a networked long-term recording of the health of our land via near real-time monitoring, precision mapping, and process-based modeling of its "blood pressure," temperature, respiration, and other vital signs of global land change. While often hidden underfoot, soils are fundamental to the earth's ecosystems and the sustainability of human society. Therefore, serious efforts must be taken to monitor soil change and its diverse functions over space and time. At the closing session of the conference, representatives from the NSF and USDA spoke about the potential funding opportunities.

This inaugural conference contributed to the celebration of the International Year of Planet Earth. A book and a special issue of two journals (Journal of Hydrology and Hydrology and Earth System Science) are planned to publish selected papers from this conference. In addition, a DVD, containing the conference proceedings (presentations, posters, video tapes, and photos), will be produced and distributed. The IUSS Hydropedology Working Group has decided that the 2^nd International Conference on Hydropedology will be held in Germany in 2012. Between now and then, a dedicated website (http://hydropedology.psu.edu/) will be used to maintain communications about this event and other hydropedology related activities to the community. For more information, please contact Henry Lin (henrylin@psu.edu, 814-865-6726).

- Henry Lin, Department of Crop and Soil Sciences, The Pennsylvania State Univ., University Park, PA.; David Chittleborough, School of Earth and Environmental Sciences, The University of Adelaide, South Australia, Australia; Hans-Joerg Vogel, Department of Soil Physics, UFZ – Helmholtz Center for Environmental Research, Germany; Kamini Singha, Department of Geosciences, Pennsylvania State University, University Park, PA, USA; and Sacha Jon Mooney, Faculty of Science, Environmental Sciences, University of Nottingham, UK.