Keynote Speakers

We are delighted to have three distinguished keynote speakers this year.  They will speak on the first two mornings of the Symposium as well as during lunch the first day.  Scheduled lecture times, subjects, and biographical information are listed below.

Dr. Richelle Allen-King

It has been known for nearly three decades that organic contaminant retardation is caused by interaction with organic carbon or carbonaceous matter (CM), quantified as the fraction organic carbon (foc) content. What is not as well recognized or applied in practice is the impact that the type of CM can have on transport - especially important in low foc aquifers. Common in sediments deposited since the late Devonian, condensed forms of CM can exhibit Kocs (=Kd/foc where Kd is the sorption distribution coefficient at a particular contaminant concentration) that are 10 to 100 times greater than the ‘literature’ or ‘reference’ values. These ‘excess’ Kocs result from adsorption interactions between the contaminants and condensed CM that also cause nonlinear (e.g., concentration dependent) and competitive sorption among similarly structured organic contaminant co-solutes.

This presentation will discuss how a geologic framework can inform models of the transport properties of sedimentary aquifers (from the grain to the aquifer scale) and provide the basis for contaminant transport. The source rocks, environment, and post-depositional processes all play important roles in controlling the types of CM deposited and retained within sedimentary aquifers. At the ‘within aquifer’ scale – we demonstrate a lithofacies approach to describe and model the spatial distribution of reactive transport properties. Contrasts between field sites in different regions exemplify differing behaviors towards organic contaminants that are related to source materials and post-depositional processes through understanding the type of CM and geology. Practical examples of the effects of ‘excess’ sorption on contaminant mass storage, transport and remediation will be presented.

Dr. Allen-King holds a Ph.D. (1991) in Hydrogeology from the University of Waterloo and a B.A. (1983) in Chemistry (Earth Science specialization) from the University of California at San Diego.  Her specialty is Hydrogeochemisty.  She has authored numerous publications and was the 2003 NGWA Darcy Distinguished Lecturer.  For more information, visit Dr. Allen-King's Web site.

Dr. Ingrid Verstraeten

Senior Physical Scientist - Hydrologist
International Water Resources Branch
U.S. Geological Survey, Reston VA
Tuesday April 28, 12:00 PM (Lunch)
USGS Capacity-Building Efforts in Water Resources in the Developing World – Issues and Challenges

Access to adequate and safe supplies of water for poor people is a major problem in developing countries, affecting health, food supply and security. A growing world population has increased the demand for water while water resources remain limited. Currently, millions of people in developing countries are lacking a potable water supply and the scientific information needed to assess and manage their water resources. To remediate these conditions, a sound monitoring infrastructure and management strategy are needed to assess, understand, and manage water resources. The development of famine early warning systems have inspired the innovative use of remote sensing, numerical modeling, geographic information systems and decision support systems for enhancing water-resources assessments and management. Generally, in order for these remedial measures to be successful the capacity of the local citizens, managers and government entities needs to be significantly increased. These efforts mostly focus on higher education, including institutional capacity-building and networking, education for research at the postgraduate level, continuing professional education and activities targeting the training of trainers.

The U.S. Geological Survey (USGS) is a fact-finding agency that collects and analyzes data, providing both scientific understanding about natural resources and impartial multi-disciplinary science. Its science has been crucial to the quest for sustainable and safe drinking water supplies and the development of sound environmental and water-resources management policies in the U.S. As part of its International mission, the USGS engages in numerous partnership efforts to improve the understanding and wise management of water resources throughout the world. Recently, the USGS has cooperated with local, regional, and national agencies and non-governmental organizations (NGO’s) using variable approaches depending on country and agency or NGO needs/mission. Most recently, the USGS has been active in Afghanistan, Pakistan, Jordan, United Arab Emirates, Sudan, Ethiopia, Madagascar, Cape Verde, Mozambique and Ecuador. The keynote talk will focus on various capacity building approaches depending on the institutional capacity of the developing country.

Dr. Verstraeten holds a Ph.D. (1994) in Agronomy and an M.S. (1987) in Geology (hydrogeology/geochemistry emphasis) from the University of Nebraska-Lincoln and an L.S. (1979) and C.S. (1977) in Geology from Catholic University of Leuven, Belgium.  She currently works on science, water, and sustainable development issues pertaining to the United Nations and United Nations Educational, Scientific, and Cultural Organization (UNESCO), provides technical assistance on water policy development to the U.S. State Department, and manages projects in the Middle East, Africa, South America, and Asia that are funded by the U.S. Agency for International Development, the U.S. State Department, the National Academy of Sciences, the Millennium Challenge Corporation, and the World Bank.  She has also served as the USGS water resources liaison to U.S. Department of Homeland Security.  Previously, she managed the Contaminant Hydrology Section of the USGS Maryland-Delaware-Washington D.C. Science Center.

Dr. Gary Weissmann

Associate Professor
Albert and Mary Jane Black Chair in Hydrogeology
Department of Earth and Planetary Sciences
University of New Mexico
Wednesday April 29, 8:30 AM
The Influence of Heterogeneity at Multiple Scales on Groundwater Flow and Dispersion Character

In sedimentary aquifers, groundwater-flow velocities are strongly influenced by the heterogeneity of lithofacies present in the system. The variable velocity field results in a non-Fickian (or non-Gaussian) dispersion character, contrary to dispersion distributions commonly used in current groundwater models. This dispersion character appears to occur at all scales – from pore-scale to regional-scale – and may be reasonably captured by a power law distribution.

Models that reasonably reflect the geologic heterogeneity have the potential to help resolve statistical distributions and possible dispersion parameters that may capture this velocity variability. At the small-scale (meter-scale), we use terrestrial lidar to develop lithofacies maps of outcrop analogs, producing models that show significant groundwater focusing into high-conductivity zones. At larger scales (plume to regional scales), we applied transition probability geostatistics to represent the heterogeneity. Transport simulations through all of these models show the non-Fickian character. These results show the importance of capturing aquifer heterogeneity in order to reasonably represent groundwater flow systems for both contaminant transport and water supply models, and they also indicate directions of focus for future studies.

Dr. Weissmann holds a Ph.D. (1999) in Hydrogeology from the University of California-Davis and an M.S. (1988) and a B.A. (1981) in Geology from the University of Colorado.  His research focuses on stratigraphic approaches to groundwater flow and contaminant transport modeling.  He teaches hydrogeology, stratigraphy, and sedimentology.  For more information, visit Dr. Weissmann's  Web site.