The Committee on Hydrologic Science (COHS) of the National Research Council (NRC) is engaged in studying the priorities and future strategies for hydrologic science. In order to involve a broad community representation, COHS is organizing workshops on priority topics in hydrologic science. These efforts will culminate in reports from the NRC on the individual workshops as well as a synthesis report on strategic directions in hydrologic science. The first workshop-Predictability and Limits-to-Prediction in Hydrologic Systems-was held at the National Center for Atmospheric Research in Boulder, Colorado, September 21-22, 2000. Fourteen technical presentations covered basic research and understanding, model formulations and behavior, observing strategies, and transition to operational predictions.

The availability of fresh water is potentially one of the most pervasive crises of the coming century. Water-related decisions will determine the future of major ecosystems, the health of regional economies, and the political stability of nations. A vigorous program of research in hydrologic sciences can provide the basis for sound water management at local, regional, national, and international levels.

The Committee on Hydrologic Science was established by the National Research Council in 1999 to identify priorities for hydrologic science that will ensure its vitality as a scientific discipline in service of societal needs. This charge will be performed principally through a series of studies that provide scientific advice on the hydrologic aspects of national program and U.S. hydrologic contributions to international programs.

This first report contains a preliminary assessment of the hydrologic science content of the U.S. Global Change Research Program (USGCRP). Because this is a short and focused report, little effort is spent to reaffirm the established and successful elements of the USGCRP. In fact, the Committee generally endorses the findings of the National Research Council (NRC) report Global Environmental Change: Research Pathways for the Next Decade (NRC, 1998a; the so-called Pathways report) in this respect. Instead the attention here is directed toward the most critical missing hydrologic science elements in the FY2000 USGCRP. This brings the focus to the terrestrial component of the water cycle. The integrative nature of terrestrial hydrology could significantly strengthen the USGCRP.

Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the "conventional wisdom" that climate change will "accelerate" the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.

Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the "conventional wisdom" that climate change will "accelerate" the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.

The Committee on Hydrologic Science (COHS) of the National Research Council (NRC) is engaged in studying the priorities and future strategies for hydrologic science. In order to involve a broad community representation, COHS is organizing workshops on priority topics in hydrologic science. These efforts will culminate in reports from the NRC on the individual workshops as well as a synthesis report on strategic directions in hydrologic science. The first workshop-Predictability and Limits-to-Prediction in Hydrologic Systems-was held at the National Center for Atmospheric Research in Boulder, Colorado, September 21-22, 2000. Fourteen technical presentations covered basic research and understanding, model formulations and behavior, observing strategies, and transition to operational predictions.

Estimates of groundwater recharge and discharge rates are needed at many differentscales for many different purposes. These include such tasks as evaluating landsliderisks, managing groundwater resources, locating nuclear waste repositories, and estimatingglobal budgets of water and greenhouse gasses. Groundwater Fluxes AcrossInterfaces focuses on scientific challenges in (1) the spatial and temporal variability ofrecharge and discharge, (2) how information at one scale can be used at another,and (3) the effects of groundwater on climate and vice versa.

The availability of fresh water is potentially one of the most pervasive crises of the coming century. Water-related decisions will determine the future of major ecosystems, the health of regional economies, and the political stability of nations. A vigorous program of research in hydrologic sciences can provide the basis for sound water management at local, regional, national, and international levels.

The Committee on Hydrologic Science was established by the National Research Council in 1999 to identify priorities for hydrologic science that will ensure its vitality as a scientific discipline in service of societal needs. This charge will be performed principally through a series of studies that provide scientific advice on the hydrologic aspects of national program and U.S. hydrologic contributions to international programs.

This first report contains a preliminary assessment of the hydrologic science content of the U.S. Global Change Research Program (USGCRP). Because this is a short and focused report, little effort is spent to reaffirm the established and successful elements of the USGCRP. In fact, the Committee generally endorses the findings of the National Research Council (NRC) report Global Environmental Change: Research Pathways for the Next Decade (NRC, 1998a; the so-called Pathways report) in this respect. Instead the attention here is directed toward the most critical missing hydrologic science elements in the FY2000 USGCRP. This brings the focus to the terrestrial component of the water cycle. The integrative nature of terrestrial hydrology could significantly strengthen the USGCRP.

The Committee on Hydrologic Science (COHS) of the National Research Council (NRC) is engaged in studying the priorities and future strategies for hydrologic science. In order to involve a broad community representation, COHS is organizing workshops on priority topics in hydrologic science. These efforts will culminate in reports from the NRC on the individual workshops as well as a synthesis report on strategic directions in hydrologic science. The first workshop-Predictability and Limits-to-Prediction in Hydrologic Systems-was held at the National Center for Atmospheric Research in Boulder, Colorado, September 21-22, 2000. Fourteen technical presentations covered basic research and understanding, model formulations and behavior, observing strategies, and transition to operational predictions.

The availability of fresh water is potentially one of the most pervasive crises of the coming century. Water-related decisions will determine the future of major ecosystems, the health of regional economies, and the political stability of nations. A vigorous program of research in hydrologic sciences can provide the basis for sound water management at local, regional, national, and international levels.

The Committee on Hydrologic Science was established by the National Research Council in 1999 to identify priorities for hydrologic science that will ensure its vitality as a scientific discipline in service of societal needs. This charge will be performed principally through a series of studies that provide scientific advice on the hydrologic aspects of national program and U.S. hydrologic contributions to international programs.

This first report contains a preliminary assessment of the hydrologic science content of the U.S. Global Change Research Program (USGCRP). Because this is a short and focused report, little effort is spent to reaffirm the established and successful elements of the USGCRP. In fact, the Committee generally endorses the findings of the National Research Council (NRC) report Global Environmental Change: Research Pathways for the Next Decade (NRC, 1998a; the so-called Pathways report) in this respect. Instead the attention here is directed toward the most critical missing hydrologic science elements in the FY2000 USGCRP. This brings the focus to the terrestrial component of the water cycle. The integrative nature of terrestrial hydrology could significantly strengthen the USGCRP.

Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the "conventional wisdom" that climate change will "accelerate" the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.

Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the "conventional wisdom" that climate change will "accelerate" the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.

The Committee on Hydrologic Science (COHS) of the National Research Council (NRC) is engaged in studying the priorities and future strategies for hydrologic science. In order to involve a broad community representation, COHS is organizing workshops on priority topics in hydrologic science. These efforts will culminate in reports from the NRC on the individual workshops as well as a synthesis report on strategic directions in hydrologic science. The first workshop-Predictability and Limits-to-Prediction in Hydrologic Systems-was held at the National Center for Atmospheric Research in Boulder, Colorado, September 21-22, 2000. Fourteen technical presentations covered basic research and understanding, model formulations and behavior, observing strategies, and transition to operational predictions.

Estimates of groundwater recharge and discharge rates are needed at many differentscales for many different purposes. These include such tasks as evaluating landsliderisks, managing groundwater resources, locating nuclear waste repositories, and estimatingglobal budgets of water and greenhouse gasses. Groundwater Fluxes AcrossInterfaces focuses on scientific challenges in (1) the spatial and temporal variability ofrecharge and discharge, (2) how information at one scale can be used at another,and (3) the effects of groundwater on climate and vice versa.

The availability of fresh water is potentially one of the most pervasive crises of the coming century. Water-related decisions will determine the future of major ecosystems, the health of regional economies, and the political stability of nations. A vigorous program of research in hydrologic sciences can provide the basis for sound water management at local, regional, national, and international levels.

The Committee on Hydrologic Science was established by the National Research Council in 1999 to identify priorities for hydrologic science that will ensure its vitality as a scientific discipline in service of societal needs. This charge will be performed principally through a series of studies that provide scientific advice on the hydrologic aspects of national program and U.S. hydrologic contributions to international programs.

This first report contains a preliminary assessment of the hydrologic science content of the U.S. Global Change Research Program (USGCRP). Because this is a short and focused report, little effort is spent to reaffirm the established and successful elements of the USGCRP. In fact, the Committee generally endorses the findings of the National Research Council (NRC) report Global Environmental Change: Research Pathways for the Next Decade (NRC, 1998a; the so-called Pathways report) in this respect. Instead the attention here is directed toward the most critical missing hydrologic science elements in the FY2000 USGCRP. This brings the focus to the terrestrial component of the water cycle. The integrative nature of terrestrial hydrology could significantly strengthen the USGCRP.