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Project Information

Project Information

A Workshop on Global Change and Extreme Hydrologic Events: Testing Conventional Wisdom

Project Scope:

A two-day public workshop on Global Change and Extreme Hydrology: Testing Conventional Wisdom will be planned and conducted by an ad hoc planning committee under the auspices of the standing Committee on Hydrologic Sciences (COHS). The workshop will foster discussions among members of the science and applications communities about the hydrologic and climatologic perspective on extreme hydrologic events. The workshop will be held in Washington, D.C. and is expected to feature presentations by experts followed by open discussions on the following topics:

·         Is the global hydrologic cycle accelerating and what does this acceleration look like? Is precipitation becoming more intense? Is drought frequency and severity becoming more prominent?

·         Are hydrologic fluxes associated with floods and droughts changing at the regional scale?

·         Floods and drought from a climatologic and hydrologic perspective-- How do we reconcile the two?

·         How does the science compare to the public debate? 


The committee will author a report of the workshop with findings and conclusions.


Status: Completed


Project Duration (months): 10 month(s)

RSO: Helsabeck, Laura


Water Science and Technology Board


Earth Sciences

Geographic Focus:

Committee Membership

Committee Post Date: 01/07/2010

Charles J. Vorosmarty - (Chair)
City University of New York

Charles Vörösmarty is Director of the Global Environmental Sensing and Water Sciences Initiative, Professor in Civil Engineering Department, and NOAA-CREST Distinguished Scientist at The City University of New York. He was formerly Professor at the Institute for the Study of Earth, Oceans, and Space at the University of New Hampshire as well as founder and Director of its Water Systems Analysis Group. His research interests focus on the development of computer models, remote sensing application and geospatial data sets used in synthesis studies of the interactions among the water cycle, climate, biogeochemistry, and anthropogenic activities. His studies are built around local, regional, and continental to global-scale modeling of water balance, discharge, constituent fluxes in river systems, and the analysis of the impacts of large-scale water engineering on the terrestrial water cycle. He is a founding member of the Global Water System Project representing the inputs of more than 200 international scientists under ICSU's Global Environmental Change Programs. In this capacity he is spearheading efforts to develop global-scale indicators of water stress, to develop and apply databases of reservoir construction worldwide, and to analyze coastal zone risks associated with water diversion. Dr. Vörösmarty also serves on the US Arctic Research Commission, the NSF-ARCSS Committee (AC), and the Arctic HYDRA International Polar Year (IPY) Planning Team. He has served on NRC panels to review NASA's polar geophysical data sets and the decadal study on earth observations, and is co-Chair of the NSF-Arctic CHAMP hydrology initiative. For the United Nations he served as consultant to the 24-agency UN World Water Assessment Program and represented the International Council of Scientific Unions at recent UN Commission on Sustainable Development meeting

Victor R. Baker
University of Arizona

Victor R. Baker is regents professor in the Department of Hydrology and Water Resources at the University of Arizona. He is also professor of geosciences and professor of planetary sciences at the University of Arizona. His research interests include geomorphology, flood geomorphology, paleohydrology and paleoclimatology, Quaternary geology, natural hazards, history and philosophy of the Earth Sciences, and the interface of environmental science with public policy. Dr. Baker is a Fellow of the American Association for the Advancement of Science and a past Chair of its Geology and Geography Division. He is also a Fellow of the Geological Society of America, and a past President of the Society. He has served on numerous panels and committees of the National Research Council including the Chair of the U. S. National Committee for the International Union for Quaternary Research (INQUA). He currently is Vice-President of INQUA's Commission on Global Continental Paleohydrology. He holds a B.S. from Rensselaer Polytechnic Institute (1967) and a Ph.D. from the University of Colorado.

Dennis P. Lettenmaier
University of Washington

Dennis P. Lettenmaier received his B.S. in Mechanical Engineering (summa cum laude) at the University of Washington in 1971, his M.S. in Civil, Mechanical, and Environmental Engineering at the George Washington University in 1973, and his Ph.D. at the University of Washington in 1975. He joined the University of Washington faculty in 1976 and directs the Surface Water Hydrology Research Group there. Dr. Lettenmaier's interests cover hydroclimatology, surface water hydrology, and GIS and remote sensing. He spent a year as visiting scientist at the U.S. Geological Survey in Reston, VA (1985-86) and was the Program Manager of the Land Surface Hydrology Program at NASA Headquarters in 1997-1998. He was a recipient of ASCE's Huber Research Prize in 1990, is a Fellow of the American Geophysical Union and American Meteorological Society, and is the author of over 100 journal articles. He is currently Chief Editor of the American Meteorological Society Journal of Hydrometeorology, and recently served on the NRC Committee on the National Ecological Observatory Network (2003-2004). He presently chairs the panel on Water Resources and the Global Hydrologic Cycle for the NRC study on Earth Science and Applications from Space.
Daniel P. Loucks
Cornell University

Daniel P. Loucks (NAE) teaches and directs research in the application of economic theory, environmental engineering and systems analysis methods to the solution of environmental and regional water resources problems. He is author of the book "Water Resources Systems Planning and Management." He has been a Research Fellow at Harvard University, an Economist at the Development Research Center of the World Bank, a Research Scholar at the International Institute for Applied Systems Analysis in Austria, and as a Visiting Professor at the Massachusetts Institute of Technology, the University of Colorado in Boulder, the University of Adelaide in South Australia, Aachen University of Technology in Germany, the Technical University of Delft and the International Institute for Hydraulic and Environmental Engineering in Delft in The Netherlands, and the University of Texas in Austin. He has served as a consultant to private and government agencies and various organizations of the United Nations, the World Bank, and NATO involved in regional water resources development planning in Asia, Australia, Eastern and Western Europe, the Middle East, Africa, and Latin America. In the past three years he has had appointments at Delft Hydraulics in The Netherlands, the Institute for Water Resources of the US Army Corps of Engineers, and the South Florida Water Management District, all involving water resources and ecosystem planning and management projects. In addition to his membership in the NAE, he has served on seven NRC committees and boards.
George F. Smith
Riverside Technology, Inc.

Dr. George F. Smith is a Senior Program Manager with Riverside Technology, Inc. As an integral member of Riverside’s leadership, technical, and management teams, Dr. Smith identifies and develops solutions to meet the needs of Riverside’s growing client base in areas such as environmental sustainability and climate change. Dr. Smith spent 33 years with the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS). He started his career as a research hydrologist and held many leadership positions within NOAA, including chief of the National Weather Service Hydrology Laboratory and acting director of the Office of Hydrologic Development. Dr. Smith has broad experience in hydrologic science, technology, and operations. His last role in the federal government was as NOAA’s Weather and Water Goal Lead, responsible for long-term planning and programming for approximately one-quarter of NOAA’s budget, focused on weather and water services, and the research necessary to support and enhance them. He managed the integration of hydrologic scientific software into the Advanced Weather Interactive Prediction System, the high-speed computer and communication system that allows forecasters to quickly access and compile weather data gathered by radars, satellites, and automated surface observing systems, all in one workstation. He also oversaw the Advanced Hydrologic Prediction Service program, which combines the use of remote sensing, data automation and advanced computer modeling to analyze river data and create graphical displays of flood probability forecasts, including flood-forecast maps, pinpointing areas where flooding may occur. Dr. Smith received his B.S. degree in civil engineering from Massachusetts Institute of Technology and his M.S. degree and Ph.D. in environmental engineering sciences from the University of Florida. In his service with the federal government, Dr. Smith received outstanding performance awards in all of his scientific and leadership roles, and was the recipient of the U.S. Department of Commerce’s Silver Medal for Meritorious Service and the Distinguished Career Award.
Chunmiao Zheng
University of Alabama

Chunmiao Zheng is professor of Hydrogeology and SSPA Faculty Fellow in the Department of Geological Sciences at the University of Alabama. He received a B.S. in geology in 1983 and did postgraduate work in geology and applied mathematics in 1983-1984 at Chengdu Institute of Geology in China (now Chengdu University of Technology). He received his Ph.D. in hydrogeology with a minor in civil and environmental engineering from the University of Wisconsin-Madison in 1988. Dr. Zheng's research involves contaminant transport modeling, groundwater resources and groundwater quality management, and coupling of physical transport processes with biological and geochemical reactions. He is President-Elect of the International Commission on GroundWater (IAHS), software editor and associate editor for the journal Ground Water, and a member of the Editorial Board for the Journal of Hydrology. He was treasurer of CUAHSI from 2005-2007. His text on "Applied Contaminant Transport Modeling" is on its second edition.

Committee Membership Roster Comments

New members have been added to committee as of April 21, 2010.



National Academy of Sciences Building
2101 Constitution Ave NW, Washington, DC 20418
Event Type :  

Registration for Online Attendance :   

Registration for in Person Attendance :   

If you would like to attend the sessions of this event that are open to the public or need more information please contact

Contact Name:  Laura Helsabeck
Contact Email:
Contact Phone:  202-334-3422

A workshop on
Global Change and Extreme Hydrology: Testing Conventional Wisdom

The National Academy of Sciences, 2100 C St. N.W., Lecture Room
Sponsored by the National Research Council's Committee on Hydrologic Science (COHS)

"Please note that notice of the open session portions of this meeting was inadvertently not posted in advance. The agenda for those open session portions is shown below and is followed by the minutes of what transpired at those sessions."

January 5th: Precipitation and Floods

7:30 Breakfast at your leisure (NAS cafeteria)

8:00 Welcome and Introductions Charlie Vörösmarty, Chair, COHS
Agenda Overview and Workshop Goals Dennis Lettenmaier and Vic Baker, COHS

8:15 Understanding Changes in Precipitation and Runoff with a Changing Climate
Kevin Trenberth The National Center for Atmospheric Research

9:00 Global to Regional Perspectives on Intensification of the Hydrologic Cycle: Implications for Extreme Events
Tom Huntington U.S. Geological Survey

9:45 Is Precipitation Becoming More Intense?
Pavel Groisman National Oceanic Atmospheric Administration

10:30 Break

10:45 A Process-Based “Bottom-Up” Approach for Addressing Changing Flood-Climate Relationships
Katie Hirschboeck University of Arizona

11:30 The Ghost of Flooding Past, Present, and Future
Harry Lins U.S. Geological Survey

12:15 Lunch- in the meeting room, all welcome

1:00 Planning for Nonstationary Extreme Events: Statistical Approaches
Rich Vogel Tufts University

1:45 Planning for Nonstationarity and Floods: A Management Perspective
Gerry Galloway University of Maryland

2:30 Break

2:45 Breakout groups
Rapporteurs: Vic Baker and Dennis Lettenmaier

4:00 Rapporteurs report back and summary of research and operational needs

5:00 Break

7:00 Working Dinner The Committee on Hydrologic Science
Discussion of the day’s events
Location: TBD

"Please note that notice of the open session portions of this meeting was inadvertently not posted in advance. The agenda for those open session portions is shown below and is followed by the minutes of what transpired at those sessions."

January 6th: Drought

8:00 Breakfast at your leisure (NAS cafeteria)

8:30 Welcome and Day 2 Agenda Overview Charlie Vörösmarty, Chair, COHS

8:45 Synthesis of Day 1 Dennis Lettenmaier and Vic Baker, COHS

9:00 Mechanisms for Global Warming Impacts on the Large-Scale Atmospheric Branch of the Hydrological Cycle
Richard Seager Columbia University

9:45 Connecting Global-Scale Variability to Regional Drought: Mechanisms and Modeling Challenges
Siegfried Schubert NASA Goddard

10:30 Break

10:45 Do We Need to Put Aquifers into Atmospheric Simulation Models? Evidence for Large Water Table Fluctuations and Groundwater Supported ET under Conditions of Pleistocene and Holocene Climate Change
Mark Person New Mexico Tech

11:30 Breaking the Hydro-Illogical Cycle: the Status of Drought Risk Management in the U.S.
Mike Hayes National Center for Drought Mitigation

12:15 Lunch- in the meeting room, all welcome

1:00 Breakout groups
Rapporteurs Vic Baker and Dennis Lettenmaier

3:00 Rapporteurs report back and summary of research and operational needs

4:00 Adjourn


Global Change and Extreme Hydrology: Testing Conventional Wisdom
Open Session Minutes

COHS members present
Charlie Vorosmarty
Dennis Lettenmaier
Vic Baker
Pete Loucks
Chunmiao Zheng
George Smith

Member of the public and speakers present
Dan Barnhurst
Ana Barros
Doug Bellomo
Geoff Bonnin
Ralph Cady
Jill Caverly
Shyang-Chin Lin (Samuel)
Tim Cohn
Ian Cozens
Ken Fearon
Gerry Galloway
Lisa Goddard
Pasha Groisman
Russ Harmon
Michael Hayes
Mohammad Haque
Katie Hirschboeck
Robert Hirsch
Jin Huang
Thomas Huntington
Julie Kiang
Joseph Kanney
Joe Krolak
Harry Lins
Daniel Mahoney
Henry Manguerra
Robert Mason
Mark McBride
Karen Metchis
Tom Nicholson
Rolf Olsen
Sanja Percia
Mark Person
David Raff
Richard Raione
John Randall
Karen Ryberg
Sigfried Schubert
Richard Seager
Ken See
Dave Shepp
Eugene Stakhiv
Nancy Steinberger
Will Thomas
Kevin Trenberth
Phil Turnispeed
Richard Vogel
Jerry Webb
Kathleen White

NRC Staff present
Anita Hall
Laura Helsabeck
Stephen Parker

Day 1:
The workshop planning committee (Dennis Lettenmaier, Charlie Vorosmarty, and Vic Baker) give an introductory presentation outlining the workshop agenda and goals.

Kevin Trenberth, Tom Huntington, Pavel Groisman, Katie Hirschboeck, and Harry Lins speak on the workshop topic and answer participant questions.

Participants divided into two breakout groups by last name (A-L, L-Z) to discuss the following questions:
QUESTION 1: Is there evidence for changes in extreme:
• precipitation, and
• runoff
over the last half-century (or whether changes have occurred) and how well do we understand their regional specificity over the U.S.?

QUESTION 2: To what degree do other factors beyond climatic forcings regulate the extreme nature of floods, specifically, land cover change including urbanization, the spread of impervious surfaces and loss of wetlands, and engineering works, which can both regulate (e.g. flood control dams) or amplify (e.g. stream channelization)?

QUESTION 3: What are the research needs to better understand the likely nature of changes in extreme precipitation, watershed characteristics, and floods over economic life of engineering structures (typically order 50 years)? How can uncertainty in such estimates be characterized, and used in planning?

QUESTION 4: Should current methods used for engineering design in conditions where loss of life is potentially involved (e.g., of dam spillways) reflect ongoing and projected changes in climate, and if so, how?

Day 2
Richard Seager, Sig Schubert, Mark Person, Mike Hayes speak on the workshop topic and answer participant questions.

Breakout Session
Participants divided into two breakout groups by last name (A-L, L-Z) to indentify three key issues related to this topic.

Supporting File(s)
Is it a Closed Session Event?

Closed Session Summary Posted After the Event

The following committee members were present at the closed sessions of the event:

The following committee members were present for closed session:

Charles Vorosmarty
Victor Baker
and Dennis Lettenmaier.

The following topics were discussed in the closed sessions:

For the closed statement, may I put the following:

The following topics were discussed in closed session.
1. Bias discussion.
2. Brief discussion of the workshop presentations and breakout sessions.
3. Committee assignments for workshop summary.

The following materials (written documents) were made available to the committee in the closed sessions:


Date of posting of Closed Session Summary:
January 13, 2010
Publication(s) resulting from the event:



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