Part 3 of the Water Cycle Science Plan
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CHAPTER 5 – AN INTEGRATED WATER CYCLE
SCIENCE PLAN
The uncertainties in assessing the effects of global-scale perturbations on the climate
system are due primarily to an inadequate understanding of the hydrological cycle – the
cycling of water in the oceans, atmosphere, and biosphere. Overcoming this problem
necessitates new ways of regarding a field traditionally divided amongst several
disciplines, as well as new instrumentation and methods of data collection. [Chahine,
1992]
There is growing consensus that the time is ripe to meet the challenge put forth by
Chahine (1992) eight years ago. The Committee on Global Change Research
recognized the need to understand the global water cycle as one of the critical themes
for research in the coming decade (NRC 1998). Similarly, the NRC Committee on
Hydrologic Science (NRC 1999) notes the central role of water in the working of the
Earth’s climate system and argues convincingly for an expanded program of research
to learn how this system works. Unprecedented ability to make new observations, to
visualize data, and to construct models of water-cycle processes indicate that
substantial and significant scientific progress can be made in the coming decade.
Conceptual advances also are leading to new opportunities for rapid scientific
advancement, for example, in hydrometeorology and ecohydrology.
The agencies of the USGCRP all have successful programs related to the water cycle.
Many of these are directed at needs specific to an agency's mission. All fulfill critical
needs and should be continued. Our vision is for a coordinated effort that expands the
overall scope of the collected work on the water cycle. We argue that, despite differing
cultures and missions, all of the USGCRP agencies and the scientific community in
general would benefit from a much improved knowledge base with respect to the water
cycle at long time and large spatial scales. Thus, as an overarching principle, we
believe that the initial focus of the water cycle science initiative should be on a)
seasonal to inter-annual and longer time scales and b) regional to global spatial scales.
We believe that this focus is most appropriate to the climate (as opposed to weather)
charge of the USGCRP, and to our charge from USGCRP to develop a global water
cycle science plan. Furthermore, determining priorities by such a focus has both
scientific and practical justification. Arguably, scientific challenges are greatest at these
scales and potential scientific rewards are commensurably large. We also argue that a
critical applications gap exists in the availability of useful scientific knowledge to water
managers and other stakeholders on these space-time scales. Knowledge about
hydrologic fluctuations having durations of decades to centuries is important because
the lifetimes of man-made water-resource systems and the durations of consequences
of water-resources decisions are of comparable duration. We emphasize nonetheless
that improved understanding of water cycle processes at these long time and large
spatial scales has critical implications for the management of water and protection of
ecosystems at time and space scales relevant to local decision making.
As indicated in Chapter 1, the Water Cycle Study Group sought to ascertain the
science needed (1) to determine whether the global water cycle was accelerating, (2) to
enhance our ability to make useful predictions, and (3) to develop information that
1
would mitigate the effects of water cycle calamities. We believe that these three issues
form pillars on which a science plan can be based. The scientific elements that we
believe are needed are covered in the previous three chapters. Here we present a plan
that embeds science elements selected to relate to the chosen time and space scales
into an overall "systems" framework to address the pillar initiatives.
We see three primary challenges for research efforts. The first is to deliver better and
more comprehensive data and information with enhanced resolution and increased
precision in a timely way. Successfully meeting this challenge will require integration of
data from new sensors with data from existing networks, and selective expansion of
existing observation networks. Techniques borrowed from “neighboring” disciplines, for
example those using stable isotopes, must be embraced. In addition to collection of
new data, existing long-term records must be archived and preserved carefully, and
observations must be continued indefinitely at sites with long high-quality records, so
that the patterns of temporal variability, including long-term low-frequency fluctuations,
can be defined and studied. Studies of hydrologic proxy variables such as tree rings,
varves and other sedimentary deposits, and archaeological relics must be undertaken
to extend the length of long instrumental records. The databases of proxy records must
be coordinated and integrated with instrumental databases. It is absolutely essential
that this challenge be met for two reasons. First, major scientific advances in the
environmental sciences almost always follow on the heels of new observations
(including “proxy” observations) and new instruments with increased resolution.
Research in the water cycle is no exception. Second, users of water cycle research
often need data and information themselves and not only predictions from models.
The second major challenge is to determine how predictable the water cycle is on the
time and length scales of interest. Determination of the limits of predictability will lead to
improved prediction because it will allow us to concentrate efforts on the predictable
components of the water cycle. Progress in these areas will be the most cost effective
and rapid. At the same time, less predictable or inherently unpredictable processes
must be understood and their limits of predictability assessed so we can better
appreciate the scope and magnitude of "unanticipated changes".
The third challenge follows directly – to improve our ability to predict components of the
water cycle. This challenge links directly to the other two. To improve predictions, a
comprehensive program that includes observations, process experiments, and
numerical modeling will be needed, and predictability studies will be needed to guide
development efforts.
We believe that the research plan should be implemented within a systems framework
in which data, process research, and modeling all are integrated with active feedback
from users of the research (Figure 5.1). Seasonal and longer lead-time predictions of
the tropical sea surface temperature and its effects on climate variability in other parts
of the globe have been provided to the public. An improved knowledge of the
contributions of soil moisture and other land surface processes to atmospheric
predictability are expected to enhance the accuracy of these predictions. Different
sectors have made use of this information with varying degrees of effectiveness. By
incorporating the needs of users into the way in which the predictions are made and the
observations are presented, the information can be made significantly more useful.
2
The proposed integrated plan is not simply a summary of all initiatives enumerated
under the three individual science questions. The strategy must integrate across all of
the science questions if the full extent of accomplishment that we envision is to be
realized, and cannot simply be a tree where various “ornaments” of every conceivable
kind are specific research “needs”, no matter how meritorious. Some of the
associations are easily appreciated [e.g., ocean-land-atmosphere models have a
prominent role in science question 1 (Chapter 2) and science question 2 (Chapter 3)]
and others will require cross-discipline links that have been made only weakly in the
past [e.g., the application of data assimilation techniques (Chapter 2) to models and
observations related to nitrogen transport from large watersheds to coastal oceans
(Chapter 4)]. In addition to outlining how integration might be done, the plan presented
in this chapter was developed with full recognition that priorities must be identified so
that resources can be allocated accordingly.
Figure 5.1. The systems framework for the science plan. Note that "users" (decision
makers, researchers, and other stakeholders) interact in both the modeling and
observations elements.
PRIORITIES
The framework for the elements of an integrated water cycle science initiative is an
overall systems model (Figure 5.1) under the umbrella of the initial priority focus on
climate time-space scales. In addition to the issue of improving our observational
capabilities, major issues within the initiative fall under predictability – determining what
expectations are reasonable based on science – and prediction – providing the best
methods available for delivering information to users. Figure 5.2 illustrates these
interactions. Within this overall framework, we propose three pillar initiatives. We
describe the elements of a science plan based on the pillar initiatives that draws on
individual science elements discussed in Chapters 2, 3, and 4. Tables indicating the
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linkages between the science planned for the pillar initiatives to sections of the
chapters discussing the general science questions are presented in Appendix D.
Figure 5.2. Schematic of the rationale for the integrated plan. The overall focus is on
long time and large space scales. With this backdrop, the systems model framework,
which includes scientist-stakeholder interaction (see Figure 5.1), is used. Maintenance
of existing observation programs and enhancements of them are essential. Process
based research is necessary to support model development. Finally, two key science
issues – predictability and prediction – are envisioned, bolstered with enhanced
observation programs and also appropriate process research.
PILLAR INITIATIVE #1-Determine whether or not the global water
cycle is accelerating and to what degree human activities are
responsible.
The frequency of extreme hydrological events, a critical characteristic of the
environment that affects all aspects of human society and enterprise, varies over
decadal and longer time scales. There is evidence that suggests that the global
hydrologic cycle may be accelerating, leading to an increase in the frequency of
extremes. This acceleration, if it is truly occurring, may be a result of human activities
(including, among other things, increasing the concentration of greenhouse gases in
the atmosphere and altering the landscape of the planet through changes in land cover
and land use). The resolution to the questions of whether or not the water cycle is
accelerating and, if so, to what extent the acceleration is due to human activities,
requires a focused effort on modelling changes in the global water cycle on climate
time scales, and on supporting efforts of observations, process studies, and budget
studies.
Key elements for addressing this pillar initiative are better understanding of the
processes governing space-time distributions of regional and global precipitation,
4
atmospheric water vapor, cloud processes, snow and ice dynamics, and global ocean
fluxes. Efforts to improve process understanding must be founded on better
observations of pertinent state variables, field experiments, and improvements in
coupled atmosphere-land-ocean models. Specific research priorities under this initiative
include:
•
Innovative measurements of water vapor should be incorporated into standard
measurement systems. Along with water vapor observations, improved estimates of
wind (wind profilers) should be deployed so that water vapor fluxes and moisture
convergence can be better estimated from observations and analyses. Field
campaigns over relevant global regions to characterize the water vapor and cloud
distribution, especially in the upper troposphere, should be carried out. In addition to
using state-of-the-art water vapor measurements, these experiments should be
carried out in conjunction with mesoscale, regional, and global climate models.
•
Unique new observations provided globally by experimental satellite missions such
as TRMM, Cloudsat and PICASSO/CENA will provide new insight into cloud
microphysics and 3-dimensional structure. These observations, in conjunction with
a coordinated system for processing of existing, archived cloud data are needed to
understand cloud ensemble properties and upper tropospheric moisture
distributions.
•
Current precipitation data sets need to be extended in space and time to maximize
the value of existing historical observation records. New high-resolution gridded
precipitation analyses will be critical for developing better large-scale understanding
of the global hydrologic cycle. Precipitation over the entire globe at sufficiently high
resolution to capture its diurnal variability and spatial inhomogeneities will improve
our understanding of water cycle exchanges and improve predictions at all scales.
Support of the Global Precipitation Mission (GPM), which, with its currently planned
specifications, promises to provide three-hourly, global four-kilometer precipitation
coverage, is imperative. Intensive field campaigns are needed to define
precipitation predictability. The campaigns should include a combination of
boundary layer observations, aircraft observations during precipitating events,
upward looking surface measurements, synoptic scale information, and coordinated
satellite observations. The field experiments should be accompanied by advanced
numerical experiments designed to untangle some of the uncertainties in current
modeling schemes. These experiments will provide better parameterizations for
larger scale (e.g., global) models.
•
Improved seasonally and regionally specific algorithms should be developed for
extracting snow water equivalent (SWE) from microwave brightness temperatures.
In support of these remote sensing efforts, an initiative should be undertaken to
develop a research quality data set of the climatology of snow properties – initially
over North America and eventually globally -- that integrates in situ, microwave, and
visible snow measurements. Efforts should be made to supplement the current
network of snow depth observations collected at selected manual climate observing
stations in the U.S. with weekly measurements of snow water equivalent.
•
There is a need for enhanced global ocean and ice sheet observations, combining
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satellite remote sensing, as well as long term deployment of arrays of ocean buoys
or subsurface floats, that will enable documenting, modeling and, eventually,
predicting the life cycle of global climate variability modes. Such efforts, while not
the sole province of the Water Cycle Initiative, must be closely coordinated, as they
have strong implications for improved understanding of the global water cycle. A
global ocean surface flux monitoring program that will provide, for the first time, an
estimate of the fresh water flux from atmosphere to ocean (precipitation) and from
the oceans to the atmosphere (evaporation) is critically needed. This component of
the global water cycle remains a major source of uncertainty in our ability to
characterize the fluxes of water between reservoirs and to predict fluctuations in
these fluxes at seasonal time scales. A set of coordinated field, remote sensing,
and modeling experiments designed to better understand the role of regional
anomalies in the global transport of water, and in particular, those persistent
deviations in global moisture transport that lead to extreme droughts and large area
flooding, should be carried out.
•
Nested regional climate models can provide a means of bridging the spatial scales
of atmospheric, land-surface and subsurface processes. A systematic approach to
model design and development is needed that will permit the determination of the
scales at which predictive information should be exchanged within a nested
modeling approach. This research will be heavily computational in nature and will
require enhancements to the available computing capabilities of the nation.
Improvements in computer visualization to enhance our ability to understand
hydrologic systems and allow researchers to transfer model results more readily to
the user community should be encouraged. Expanded capabilities of geographical
information systems using information on input parameters - such as elevation,
vegetation type, soil type, land use, land cover, river reaches, and hydrologic unit
boundaries - at finer spatial and temporal scales should be developed along with
distributed hydrologic models that will be enabled by such information. Fellowship
and exchange programs should be developed to foster the involvement of scientists
at all levels (including students) in the development and improvement of coupled
land-atmosphere models.
•
A continuing effort to use observations to close water budgets is critical. New data
sets geared specifically for budget studies need to be developed. Because analysis
budgets provide the main link between models and observations, they should be
rigorously tested against all observations, especially those hydrometeorological
observations developed to cover wide space and time scales. New continental and
global hydrometeorological data sets will be required to support these activities.
These include gridded (or equivalent) observations of streamflow, naturalized
streamflow and observed streamflow over continental domains and gridded highresolution precipitation data. Expanded budget studies involving the snow
accumulation, melt, runoff, evaporation of snow in continental regions should also
be undertaken to understand how snow contributes to the water cycle.
PILLAR INITIATIVE #2-Determine the deeper scientific understanding
that is needed to reduce substantially the losses or costs associate
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with water-cycle calamities such as droughts, floods and coastal
disruptions.
Through a better understanding of the hydrological cycle and its relationship to
meteorological, climatological, biological, and other phenomena, we can increase our
skill in predicting regional water supply and biogeochemical anomalies at seasonal and
longer time scales and thereby, through corresponding resource management,
minimize associated economic losses.
Key elements for addressing this pillar are improvement of model predictive skill
through testing of models with better observations, explicitly addressing conceptual
model and parameter uncertainties, and conducting comparisons among different
codes using data from carefully designed field experiments. Specific research priorities
under this initiative include the following.
•
Improved continuing observations via surface networks and sensors are needed.
The spatial and temporal resolution of precipitation measurements should be
improved. The accuracy of NEXRAD and satellite estimates is ultimately limited by
the gauge observations used in their calibration. Therefore, the gauge network
remains the backbone of the precipitation observation system, especially for
climatological applications. Current precipitation data sets need to be extended in
space and time to maximize the value of existing historical observation records. A
regional-scale network of sites should be developed at which surface
meteorological variables, soil moisture, and groundwater levels would be measured.
A network of in-situ monitoring stations near mouths of major rivers in the U.S.
should be put in place to couple water fluxes with fluxes of dissolved and
suspended material, in particular linking the water, nitrogen and carbon cycles.
International partners should be encouraged to establish comparable networks to
provide global scale measurements. A powerful method for determining the gaps in
observations is observing system simulation (OSS). An OSS methodology uses a
predictive model, a set of measurements that are either already operational or are
prospective, and a data assimilation system that optimally combines observations
and model output. OSS methodology has not been widely used for land surface
simulation, but has important implications for the design of both surface and
satellite observing systems.
•
Satellite observations, particularly of hydrological variables not yet remotely sensed,
and for which technology development may be required, must be pursued. New
observation methods offer promise for better defining variations in subsurface
moisture storage. NASA’s post-2002 plans for an experimental soil moisture
demonstration mission, aiming to provide about 10 km spatial resolution and 2-3
day repeat cycle, should be advanced. The antenna technology to support such a
mission needs to be pursued. Improved estimates of water contained in seasonal
snow packs should be developed. The post-2002 plans of NASA for an exploratory
cold seasons/regions process observing mission aiming to yield higher resolution,
global estimates of snow water storage should be carried forward. A global
capability to estimate, in near-real time, the discharge of major rivers at their mouths
and at key points within the continents, which would be achieved by NASA’s
proposed HYDRologic Altimetry SATellilte (HYDRA-SAT) mission, should be
advanced.
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•
Field campaigns and intensive observation programs that facilitate improved
understanding of effects of interactions between and among one or more of the
land, ocean, and atmosphere are needed to isolate the effects of fast and slow
processes in the hydrological cycle. Enhanced field campaigns should include a
multi-year component, in which large-scale surface conditions, surface fluxes, and
atmospheric variables would be observed. These large-scale observations would
be supplemented with simultaneous observations of the slower components of the
land system, such as groundwater levels. Nested basin studies in three to five river
systems with varying land cover and levels of human disturbance and regulation
should be conducted to characterize and improve understanding of linked water, C
and N transport and transformation processes. Studies on both terrestrial and
aquatic ecosystems should be part of the program. Basins should be selected over
a range of bio-hydro-climatic conditions (water-limited, energy-limited, and nutrientlimited systems) so that models can be adequately stressed and tested.
•
The development and improvement of coupled land-atmosphere models should be
accelerated through improvements in the use of data assimilation techniques. One
existing vehicle for this is a new U.S. multi-agency initiative known as the Land Data
Assimilation System or LDAS. LDAS should be supported and expanded to include
a focus on data representing snowpack and high latitude glaciers. Studies to
examine if a two-way land-atmosphere coupling or modulation of climate by local
hydrologic processes results in predictability that can be exploited through coupled
modeling should be undertaken. For seasonal and longer lead prediction of water
fluxes, a modeling strategy must be developed that best minimizes the propagation
of uncertainty among components of a predictive model. Linking global coupled
ocean-atmosphere models to an integrated system model that can produce
predictions and associated estimates of uncertainty that are suitable for guiding
decision-making in water resources management will require data at high spatial
and temporal resolution. Computational resources and observational data for
initializing and verifying the models should be supported. Process models of
coupled water, carbon, and nitrogen transport and transformation in aquatic
ecosystems and other terrestrial components of the hydrologic cycle (e.g. through
soil, groundwater etc.) that can be tested against data from integrated databases
and results of field studies should be developed. Model development and testing
will also require focussed, small-scale experimental studies to elucidate processes.
•
Quantification of fluxes among atmospheric, surface and subsurface reservoirs
must be a priority. Measurements should include surface water fluxes, water
content, pressure, and temperature in the unsaturated zone, and water levels and
temperatures in the saturated zone. Geophysical measurements using
electromagnetic induction or ground-penetrating radar should be used to interpolate
and extrapolate information between monitoring locations at a site. Data on
environmental tracers such as chloride, tritium, tritium/helium and
chlorofluorocarbons should be measured in the unsaturated or saturated zones to
date the water for recharge estimation and to evaluate flow mechanisms. A
national network of groundwater monitoring wells for both water level and water
chemistry is essential for groundwater recharge characterization and for the
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identification of long-term trends due to pumping, drought, and land-use change.
•
A knowledge-transfer initiative should be designed to integrate user needs into the
development of the research agenda and to ensure that research results are
provided in useful form. Estimates of the natural variability of surface hydrological
processes that can be incorporated into water resource systems design and
management, with reduced dependence on historical observations, should be
developed. Ensemble forecast products for operation of water resource systems
should be produced, with primary focus on reservoir systems (or, in some cases,
free-flowing rivers), but with implications for ground water in systems that
conjunctively use surface and groundwater.
•
Ocean-land-atmosphere interactions are critically important to understanding how
water-cycle calamities may arise. A substantial effort must be made to achieve
better understanding of the phenomena that give rise to major departures in the
behavior of centers of deep tropical convection, and therefore lead to persistent
anomalies in global circulation, moisture transport, and hence large area droughts
and floods. Enhanced global ocean observations and coordinated field campaigns
should be used to study changes in heat and water fluxes between the surface and
the global atmosphere, which directly impact the global water cycle and continental
hydrologic processes.
PILLAR INITIATIVE #3-Develop the scientifically-based capacity to
predict the effects of changes in land use, land cover and cryospheric
processes on the cycling of water and its associated geochemical
constitutents.
An important hypothesis has been advanced relating to human impact on vulnerability
of water resources, namely that changes in land and water use (including, for instance,
irrigated agriculture, deforestation, urbanization) are increasing rates of water cycling
through terrestrial reservoirs and are altering storage in these reservoirs, making water
resources increasingly vulnerable to extreme events. Cryospheric processes, which can
be considered ephemeral changes in land cover, are critically important to water
resources issues (for example, snowmelt is the primary source of runoff in the western
U.S.). Furthermore, cryospheric processes have important effects on the cycling of
water and energy between the land and atmosphere
Comprehensive data sets should be assembled to enable evaluation of land cover
change as related to the surface water cycle. This activity would draw on existing
efforts to characterize changes in land cover using satellite and other data sources, but
would be linked to information about the land surface water cycle, in both managed and
natural environments. A program of enhanced, sustained observations of key state
variables should be used to evaluate statistical relationships and physically based
models among land cover and water movement at the land surface. Numerical
modeling should be used to evaluate susceptibility of water resources to climate
variability and to land use and land cover changes and to changes in processes related
to snow and ice dynamics. Specific research priorities under this initiative include the
9
following.
•
Existing surface flux networks to measure water, energy, carbon, and nitrogen
fluxes should be expanded to include more sites and to provide a complete suite of
surface heat and radiative fluxes, and hydrologic state variables (including soil
moisture), sufficient to close the local energy balance. A rotating sub-network to
expand the range of land cover types and hydroclimatic conditions represented
should be implemented. Evaporation over the ocean also needs to be monitored
on a regular basis rather than as part of limited field experiments. A concerted
effort to simulate evaporation correctly at specific sites over land and ocean should
be undertaken. Those aspects of the U.S. Geological Survey stream gauging
program that are critical to the estimation of water and biogeochemical transport
within and from the continent should be strengthened. Strategic expansion and
augmentation of existing streamflow and water quality monitoring stations should be
planned to facilitate estimation of the movement of C and N as well as nutrients and
other dissolved and suspended constituents, with particular focus on rivers draining
into estuaries which have had hazardous algal blooms in the past decade..
Advanced technology should be imported and new sensors developed to enable
improvements to in situ monitoring of water flows and concentrations of dissolved
and suspended constituents. The detectors developed would be useful in a wide
range of routine water quality studies and should include sediment monitoring.
•
A set of global land hydrology validation sites should be established, at which
continuing observations of surface moisture and energy fluxes would be collected,
as well as subsurface moisture (saturated and unsaturated zones). The data
should be collected over closed catchments large enough to allow closure of the
surface water budget. These continuing observations should be supplemented by
periodic rotating field campaigns, which would integrate surface, aircraft, and
satellite observations.
•
A cold seasons initiative should be implemented and include aspects of a)
retrospective data analysis over a range of spatial scales from subcontinental,
continental to global, b) model experiments to help isolate the linkages, and c) field
experiments, which would include a focus on spatial scales that affect not only the
role of cold seasons process on moisture storage at the land surface, but also on
larger scale land-atmosphere interactions associated with the role, for instance, of
snow presence-absence on albedo, frozen surface processes on land-atmosphere
turbulent energy transfer, and riverine runoff on the circulation of large water bodies
like the Arctic Ocean.
•
Large-scale and basin-scale experiments should be carried out to provide an
effective means for improving models in terms of representing the relevant
processes, estimating model parameters, and validating model simulations and
predictions. The experiments should evaluate fluxes between hydrologic reservoirs
such as evapotranspiration, recharge and surface water groundwater interactions in
watersheds that have different types of land cover, and/or a major and rapid
anthropogenic effect. The studies should be integrated with related work to
characterize and improve understanding of linked water, C and N transport and
transformation processes, and should be incorporated in process models of
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coupled water, carbon, and nitrogen transport and transformation in aquatic
ecosystems and other terrestrial components of the hydrologic cycle.
•
Model testing facilities should be established at existing weather and climate
prediction centers (like NCEP), which would be charged with facilitating model
evaluation and the transfer of methods from the general research to the operational
modeling community. These facilities should promote standardized flux couplers
and interfaces, standardized archiving, and other technical innovations (like
visualization and parallel software structures) that would enhance the ability to use
center models and data streams for model development.
•
A new program in the science and mathematics of water cycle predictability that will
guide the applications of atmospheric and hydrologic theories over a broad range of
space and time scales is needed. Climate predictions on seasonal and longer time
scales must be made within a probabilistic framework that takes into account the
uncertainty of the initial and boundary conditions as well as the inherent
characteristics of the distribution of possible states that may ensue from the given
initial state. Research is required to place current ad hoc methods of producing
ensemble model predictions on a firmer theoretical basis.
•
The past successes of including vegetation functional controls on surface water and
energy balances over meteorological time scales, should be followed with efforts to
handle the vegetation's slower, structural responses to changes in climate and land
use. Since these changes in vegetation (e.g. structure, density, and species
distribution) affect the cycling of water, they must be dynamically included in water
cycle models to understand and predict accurately the behavior of the water cycle
over the longer time scales on which vegetation distributions shift and change.
Analysis of the pathways by which a changing climate interacts with a dynamic
biosphere (with respect to carbon, water, and energy exchange) will support model
development integrating atmospheric forcing, land surface mass and energy fluxes,
and vegetation dynamics.
SUMMARY
Emerging methods for observing variables that define the global water cycle,
continually advancing modeling capabilities, and new developments in the theory used
to describe coupled processes involving nonlinear feedbacks offer the potential for
rapid improvements in capabilities to predict water cycle variability over the critical
seasonal to inter-annual and longer time scales and regional to continental space
scales. The application of new measurement technologies and modeling methods to
water cycle processes will contribute results that will lead to a greatly enhanced ability
to apply science to a myriad of societal problems related to water resources. Also,
advances in water-cycle predictive capabilities can be used to inform decisions related
to land management and associated management of chemicals such as fertilizers.
Water-cycle science must proceed along three complementary tracks – observation,
modeling, and process studies. Program elements in these general areas form the
backbone of the integrated science plan. In addition, a formal knowledge-transfer
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program, one that fosters participatory, interactive research involving researchers,
decision makers, resource users, educators, and others, must be an integral, visible
component of the global water cycle research initiative.
The management of water resources in the United States requires a fully integrated
knowledge base derived from a broad mix of disciplines including not only the natural
sciences but also the fields of law, economics, sociology and political science. This
science plan is based on the existing world view of climate and water management.
The approach taken in this study has identified a number of issues based on current
trends and has recommended actions to deal with them through science initiatives and
knowledge transfer. However, it is realized that as new water problems emerge and a
more integrated view of management and science evolves, opportunities will arise for
climate and hydrologic information to benefit society through more holistic approaches
to these problems. To address these future opportunities fully, plans should be
developed for a wide ranging integrated program dealing with research on social, legal,
economic and political issues as well as the natural sciences.
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APPENDIX A – OUTLINE OF PROCEDURES
In late August and early September 1999, the U.S. Global Change Research Program
(USGCRP) appointed a Water Cycle Study Group (WCSG), chaired by George Hornberger of
the University of Virginia, to advise the USGCRP agencies on development of a Global Water
Cycle Program within the USGCRP. Other members of the study group were John Aber, Roger
Bales, Jean Bahr, Keith Beven, Efi Foufoula-Georgiou, Gabriel Katul, James L. Kinter III, Randy
Koster, Dennis Lettenmaier, Diane McKnight, Kathleen Miller, Kenneth Mitchell, John Roads,
Bridget R Scanlon, and Eric Smith. The aim was to define a USGCRP initiative for Fiscal Years
2001 and beyond. In appointing the group, Robert Corell (then Chair of the Subcommittee on
Global Change Research) noted that “Deficiencies in our understanding of the global water
cycle severely handicap efforts to improve climate prediction and guide water resource
planning. Central to this initiative is the establishment of a science community-based research
planning process complemented by an enhanced interagency coordination effort to address the
content of this effort for FY 2001 and beyond.” [The full appointment letter is reproduced below.]
A parallel Interagency Working Group (IWG), charged with coordinating agency activities,
worked on plans for implementing the science. The IWG is co-chaired by Rick Lawford of
NOAA’s Office of Global Programs and Robert Schiffer of NASA’s Earth Science Enterprise.
The WCSG first met in Washington, D.C. in early September 1999 and again in Washington in
November 1999 and in Boulder, Colorado in January 2000. At the meetings in Washington DC,
the group heard from representatives of the agencies represented on the IWG, and developed
an outline of its report. The outline identified the three major science questions that guided
development of the report. Two Town Hall Meetings, one at the AGU Fall Meeting December
13, 1999, and the other at the American Meteorological Society Annual Meeting, January 13,
2000, provided the WCSG with important input from the broader scientific community. Beginning
at the meeting in Boulder, the WCSG drafted a full report in early 2000 and posted it on the
WCSG web site (http://ontario.hydro.washington.edu/WaterStudyGroup/). along with a
summary of comments from the two Town Hall meetings. The WCSG held a two-day open
meeting for review of the draft report (March 30-31, 2000, at the Bolger Center, Potomac, MD).
Written comments also were solicited broadly from the community. The WCSG completed the
report, making revisions in response to comments received, in the Summer and Fall of 2000.
APPENDIX B – SCIENTISTS WHO PROVIDED
COMMENTS ON THE REPORT
The Water Cycle Study Group is indebted to many scientists who commented on draft
material for this report. We did not capture the names of all those who participated in
Town Hall meetings, and we can but thank them anonymously. We thank all those who
engaged in discussions at the meeting at the Bolger Center and who provided written
comments. We believe that the quality of the report was improved through these
interactions. The responsibility for the content of the report lies with the Study Group,
however, and no criticism for it should attach to those who helped by commenting on
draft material.
Robert Adler
John Albertson
Saud Amer
Fairley J. Barnes
John Bates
Hugo Berbery
David Bosch
Kaye Brubaker
Bill Capehart
Rit Carbonne
Christopher L. Castro
Thomas Croley II
Arden Davis
Don DePaolo
Chris Duffy
Dara Entekhabi
Wanda R. Ferrell
D. Furlow
Kevin Gallo
Aris P.Georgakakos
David Goodrich
Arnold Gruber
David Farrell
John Gille
Peter Groffman
Paul Hauser
Bob Hirsch
Steve Hu
Steven Hunter
Tom Jackson
Douglas L.Kane
Jinwon Kim
William Kirby
Umanu Lall
Rick Lawford
John A.Leese
David M.Legler
Bill Lewis
Gene Likens
Brent Lofgren
Danny Marks
Dick Marzolf
Dave Mathews
Tilden P.Meyers
Norman Miller
M. Miller
Chris Milly
Mitchell Moncrieff
Pierre Morel
Pat Mulholland
Sumant Nigam
Roger Pulwarty
Walter Rawls
Rick Rosen
Clinton M.Rowe
Mike Sale
John Schaake
Robert A.Schiffer
Mark Seyfried
Steven R. Shafer
Steven C. Sherwood
Peter Schultz
John Selker
Jim Shuttleworth
Caitlin F. Simpson
Everett P. Springer
Jean Steiner
Pamela L. Stephens
Paul Stern
Paul Try
Sushel Unninayar
Tom von der Haar
Kathy Watson
Robert S. Webb
Kris Wernstedt
Bob Wetzel
Evgeney Yarosh
APPENDIX C – LINKAGES
BACKGROUND
The water cycle program described in this document will provide the nucleus of a new
comprehensive US initiative aimed at fostering and accelerating global water cycle research in
the US. A few U.S. programs related to the water-cycle, already sponsored by NASA, NOAA,
NSF, DOE, USDA, USGS, EPA and the US Army are briefly discussed below. Besides laying
the groundwork for future understanding of the US water cycle, these projects are contributing
to better international scientific understanding of the global hydrologic cycle. For this reason we
first describe briefly the international setting for global water cycle research.
WCRP PROGRAMS
The World Climate Research Program (WCRP) coordinates international research programs
that are intended to foster better understanding of global climate variability and change.
Specifically, its objectives are “to develop the fundamental scientific understanding of the
physical climate system and climate processes needed to determine to what extent climate can
be predicted and the extent of man's influence on climate.” WCRP is, in turn, one of ten major
programs of the World Meteorological Organization, which is a “specialization agency” of the
United Nations. Except in rare circumstances, WCRP does not fund research, but rather has a
coordinating function. However, its priorities carry considerable weight in the design and
functioning of international climate research, both inside and outside the U.S. WCRP sponsors
five “major projects”, all of which are relevant to global water cycle research. These are
GEWEX, the Global Energy and Water Cycle Experiment, SPARC (Stratospheric Processes
and their Role in Climate), ACSYS, the Arctic Climate System Study, CLIVAR (Climate
Variability and Predictability), and WOCE (World Ocean Circulation Experiment). Each of these
international activities is briefly described below.
GEWEX
GEWEX is the scientific locus within WCRP “for studies of atmospheric and thermodynamic
processes that determine the Global hydrological cycle and water budget and their adjustment
to global changes such as the increase in greenhouse gases”. GEWEX coordinates research
designed to understand, model and predict radiative processes involving cloud, aerosol, water
vapor and their impact on radiation transfer and radiation flux divergence in the atmospheric
column. GEWEX is also has a major focus on hydrometeorological processes, involving the
transport and release heat in the atmosphere, precipitation, evapotranspiration and land surface
exchanges, including water storage on and near the surface, and run-off. Within WCRP,
GEWEX is the sole program with a major focus on land surface processes, and for this reason a
major focus of GEWEX activities involves understanding and modeling land surface hydrology
at continental and regional scales. The coordination of land surface modeling activities in
GEWEX is now being handled by GLASS, the Global Land-Atmosphere System Study.
GEWEX is not an experiment in the traditional sense; rather it is an integrated program of
research, observations, and science activities ultimately leading to prediction of variations in the
global and regional hydrological regimes. GEWEX initially encouraged a suite of exploratory
studies over relatively small experimental sites, involving intensive field observations and
theoretical process modeling, like FIFE (First ISLSCP Field Experiment, conducted at a Kansas
grassland site in the mid 1980s), a study organized by the GEWEX International Satellite Land
Surface Climatology Project (ISLSCP). Small-scale field projects like FIFE were originally
1
expected to continue until about 2000, and then merge into a new phase of global
atmospheric/hydrologic studies relying on expected new global satellite data sets.
As the understanding of the small-scale aspects of the hydrologic cycle progressed, it became
clear that the next scientific priority was to address interactions across the spectrum of spatial
scales. GEWEX therefore began to focus on the aggregation of processes from micro- or
mesoscale to synoptic or planetary scales and the inverse disaggregation of phenomena from
the larger meteorological scales to the smaller scales that are meaningful to hydrological
scientists. The initial concept of the GEWEX Continental-scale International Experiment (GCIP),
now taking place in the Mississippi River basin, was formulated in 1990 (Scientific Plan for
GCIP, WCRP, 1992). The goal was to measure, study and model coupled atmospheric and
hydrologic processes on all scales between those captured by intensive field studies on various
experimental sites, such as FIFE and BOREAS, and planetary scales that can be observed by
global observing systems. Four additional GEWEX continental-scale experiments (CSEs) have
been formed elsewhere globally, more or less following the GCIP “template”. All of the CSEs
seek to close the energy and water budgets over large land areas representative of various
climatic regimes. Among the other CSEs is the Mackenzie GEWEX Study (MAGS) undertaken
by Canada over the north-flowing Mackenzie River basin. MAGS emphasizes cold season
processes, such as snow and ice, permafrost, and arctic clouds. BALTEX (Baltic Sea
Experiment) focuses on the interactions between the Baltic Sea and the land areas draining to it
in northern Europe. The Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)
focuses on the Amazon River basin, while the GEWEX Asian Monsoon Experiment (GAME) is
ongoing at several sites in Eastern Asia. A sixth CSE may eventually be started in western
Africa.
CLIVAR
CLIVAR is a (relatively) new WCRP program designed to move improve global climate
prediction. If successful, it will provide a basis for international cooperation in modeling, and the
field studies and process understanding necessary to support improved climate prediction.
Among its goals are to identify the major modes of climate variability, unravel the mechanisms
that lead to key modes of variability, determined their predictability, and begin a demonstration
of the prediction of climate variations. The program will further understanding of how these
variations contribute to and are affected by any mean climatic changes induced by the addition
of greenhouse constituents to the atmosphere.
The overall scientific objectives of CLIVAR are to describe and understand the physical
processes responsible for climate variability and predictability on seasonal, interannual, decadal
and centennial time scales, through the collection and analysis of observations and the
development and application of models of the coupled climate system, in co-operation with
other relevant climate research and observing programs; extend the record of climate variability
over the time scales of interest through the assembly of quality-controlled paleoclimatic and
instrumental data sets; extend the range and accuracy of seasonal to interannual climate
prediction through the development of global coupled predictive models; understand and
predict the response of the climate system to increases of radiatively active gases and aerosols
and to compare these predictions to the observed climate record in order to detect the
anthropogenic modification of the natural climate signal. Nine principal research areas (PRAs)
with "natural" phenomena at their respective cores and two directed at anthropogenic climate
change have been identified to facilitate the implementation of CLIVAR. All are embodied within
three main program areas, the Global Ocean Atmosphere Land System (GOALS), Decadal to
Centennial Climate Variability (DecCen) and Anthropogenic Climate Change (ACC), and all are
2
closely linked across geographical regions and between time scales. Note that VAMOS
(Variability of the American Monsoon Systems), a project noted below in Chapter 3, is a
CLIVAR-related activity.
ACSYS
ACSYS (Arctic Climate System Study) and in particular its Hydrological Programme has the
objective of determining the space-time variability of the Arctic hydrological cycle and the fluxes
of freshwater to the Arctic Ocean. The ACSYS hydrological region is defined as all of the global
land area that drains to the Arctic Ocean. ACSYS has made some progress in assembling
consistent precipitation data sets through its Arctic Precipitation Data Archive (APDA), which is
maintained at the Global Precipitation Climatology Center in Offenbach, Germany. ACSYS has
also developed, in cooperation with the Global Runoff Data Center (GRDC) in Koblenz,
Germany, the Arctic Runoff Data Base (ARDB). The ARDB contains historical river discharge
measurements at 235 stations at the mouths of major Arctic rivers, and at the confluences of
major tributaries thereof. Although the ARDB provides reasonably complete spatial coverage
for continental scale studies, relatively few data are available beyond 1985 (see Nijssen et al,
2000), due in large part to political changes in the Former Soviet Union, and station closures in
Canada. Likewise, station closures exacerbate the problem of understanding the spatial and
temporal distributions of precipitation in the Arctic, which has always been poorly represented
by station data.
ACSYS hydrological modeling activities draw heavily on GEWEX, especially for the MAGS,
GAME-Siberia, and BALTEX Continental Scale Experiments (CSEs) which have significant
activities in the Arctic and/or cold regions. The land surface models fostered by GEWEX are
being used in off-line mode (that is, driven with surface atmospheric forcing) to produce daily
runoff estimates over the ACSYS hydrological region. ACSYS will participate in planned
GEWEX Hydrometeorological Panel (GHP) CSE transferability studies that will treat the ACSYS
hydrological region as equivalent to a CSE, and will co-ordinate with GHP a macroscale
hydrological model intercomparison activity targeted at high latitude areas.
ACSYS is presently transitioning from a regional (Arctic drainage basin) activity to have a global
focus. The new WCRP programme, which will eventually replace ACSYS, is termed Climate
and Cryosphere (CLIC). CLIC will incorporate ACSYS sea ice and oceanographic activities in
the Arctic, which will be expanded to include Antarctic research in these areas, as well as
glaciers and ice sheets. Beyond shifting from a Boreal to a bipolar focus, CLIC will also include
relevant cold season and regions processes elsewhere, such as glaciers in temperate regions,
permafrost, and ephemeral snow cover. At its annual meeting in March, 2000, the WCRP Joint
Scientific Committee approved CLIC draft Science and Coordination Plan. Version 1 of the Plan
is currently available from the WCRP web site.
WOCE
WOCE was designed to help coordinate international ocean data collection and experimental
efforts, with the intent of improving the ocean models necessary for predicting decadal climate
variability and change. The goals of WOCE are “to develop models useful for predicting climate
change and to collect the data necessary to test them.” (Goal 1) and “To determine the
representativeness of the specific WOCE data sets for the long-term behavior of the ocean, and
to find methods for determining long-term changes in the ocean circulation.” WOCE consisted
of a field phase from 1990 through 1997, which was followed by an Analysis, Interpretation,
Modelling and Synthesis (AIMS) activity that is scheduled to be completed by 2002. At that
time, its activities will be subsumed within CLIVAR (see above).
3
SPARC
The WCRP Stratospheric Processes and their Role in Climate (SPARC) study emphasizes
stratospheric processes relevant to climate, especially the absorption of solar radiation in the
stratosphere by ozone, and the role of other some stratospheric gases, including water vapor
and carbon dioxide. It also includes studies designed to better understand the two-way
interaction between stratospheric and tropospheric dynamics. Relevant activities organized by
SPARC include the construction of a stratospheric reference climatology and the improvement
of understanding of trends in temperature, ozone and water vapor in the stratosphere. One of
SPARC areas of interest directly relevant to global water cycle research is the distribution of
water vapor in the upper troposphere and lower stratosphere (UT/LS) which plays a critical role
in Earth's radiative budget and therefore in climate questions. Although it has not received the
attention paid to the anthropogenic greenhouse gases, water vapor is the most important
greenhouse gas in terms of Earth’s energy balance. . In addition, water vapor is the source of
hydroxyl radicals, which are responsible for much of the oxidizing capacity of the atmosphere,
and therefore critical are for cleansing the atmosphere of many anthropogenic compounds
dumped into the atmosphere. Water vapor is also involved in hydrolysis reactions that are
important for the removal of reactive chlorine and nitrogen species. Given the importance of
UT/LS water vapor, a number of issues immediately arise. The first, and most important, is that
we do not know the present distribution of water vapor and its temporal variations in the
tropopause region well enough to support an understanding of the fundamental processes that
affect the earth’s radiative balance. Such an understanding is a minimum requirement to being
able to develop a capability to model the present distribution mechanistically, and more
importantly, to predict its future evolution under changing conditions, such as the continued
increase of greenhouse gases in the atmosphere.
The distribution of water in the stratosphere is complicated by the nature of water as a chemical
compound, and its phase changes. In the high troposphere water vapor can be in equilibrium
with ice crystals, and move from one phase to another. Measurements must take this into
account, and allow for water in both forms in determining the mean distribution, and the
controlling mechanisms. Presently available data suggests that water vapor, especially in the
tropics, varies on a range of horizontal scales from global to regional, and down to the size of
large convective systems. Vertical scales as fine as a few meters may be important in some
cases. There are also a range of temporal scales, from annual and seasonal to a few hours,
corresponding to the spatial scales. These facts imply that more than one type of observing
campaign and a wide range of observing techniques will be required. They also indicate that
considerable scientific imagination will be needed to construct empirical models and develop a
mechanistic understanding of the ways the water distribution is maintained, and of its natural
variations. In addition, a vigorous modeling effort must accompany any measurement program.
The goals are to aid in the interpretation of the data, suggest new measurements that are
needed, and ultimately allowing mechanistic and parameterized calculations to be carried out
within large climate models.
OTHER WMO PROGRAMS
In addition to WCRP, several other WMO programs are directly relevant to global water cycle
research. These include the Global Climate Observing System (GCOS), the Hydrology and
Water Resources Programme.
GCOS and related programs
The Global Climate Observing System (GCOS) is a WMO program at the same level as WCRP,
which was established in 1992 to ensure that the observations and information needed to
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address climate-related issues are obtained and made available to all potential users. In
addition to WMO, it is co-sponsored by the Intergovernmental Oceanographic Commission
(IOC) of UNESCO, the United Nations Environment Programme (UNEP) and the International
Council for Science (ICSU). GCOS is intended to be a long-term, user-driven operational
system capable of providing the comprehensive observations required for monitoring the climate
system, for detecting and attributing climate change, for assessing the impacts of climate
variability and change, and for supporting research toward improved understanding, modeling
and prediction of the climate system. It addresses the total climate system including physical,
chemical and biological properties, and atmospheric, oceanic, hydrologic, cryospheric and
terrestrial processes. GCOS does not itself directly make observations nor generate data
products. It stimulates, encourages, coordinates and otherwise facilitates the taking of the
needed observations by national or international organizations in support of their own
requirements as well as of common goals. It provides an operational framework for integrating,
and enhancing as needed, observational systems of participating countries and organizations
into a comprehensive system focussed on the requirements for climate issues.
The Global Terrestrial Observing System (GTOS) is a U.N Food and Agriculture Organization
(FAO) program established in 1996 to provide data for detecting, quantifying, locating, and
giving early warning of changes in the capacity of terrestrial ecosystems to sustain
development. Of particular interest to this water cycle initiative is a permanent observing
system for managed and natural ecosystems, that is envisaged to include agricultural and
ecological research centers, field stations, and derived data products that will result in better
representation of global soils, vegetation, and related land cover conditions. In addition to
linkages with GTOS, GCOS builds upon, and works in partnership with, other existing and
developing observing systems such as the Global Ocean Observing System (GOOS), the
Global Terrestrial Observing System (GTOS), and the Global Observing System and Global
Atmospheric Watch of the World Meteorological Organization. GCOS will build on existing
operational and research observing, data management and information distribution systems,
which will be enhanced as necessary to meet GCOS goals. Within the United States, the newly
established U.S. GCOS office should serve as the focal point for the interface between
international GCOS activities and the U.S. water cycle program.
HWRP
The WMO Hydrology and Water Resources Programme (HWRP) promotes activities in
operational hydrology and attempts to foster cooperation between national Meteorological and
Hydrological Services. In particular, the HWRP concentrates on: the measurement of basic
hydrological elements from networks of hydrological and meteorological stations; the collection,
processing, storage, retrieval and publication of hydrological data, including data on the quantity
and quality of both surface water and groundwater; the provision of such data and related
information for use in planning and operating water resources projects; and the installation and
operation of hydrological forecasting systems. The HWRP also promotes improvements in the
capabilities in developing countries, through technology transfer and technical cooperation, so
as to enable them to assess their water resources on a continuous basis, to respond to threats
of floods and droughts and thus to meet the requirements for water and its use and
management for a range of purposes. The Program takes into consideration the existence of
global change and its hydrological impacts and the need to provide more information to the
general public and to Governments so that they can better understand the importance of
hydrology and the role of national Hydrological Services (NHSs) in their activities. The HWRP
also promotes increased collaboration between NHSs and NMSs, particularly in the provision of
timely and accurate hydrological forecasts.
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Hydrological elements are embedded in several other WMO Programs. Particular examples are
the hydrological components of the Tropical Cyclone Programme, the Education Training
Programme and that of the World Climate Programme (WCP) which is known as WCP-Water.
There are strong links between hydrology and meteorology through the study of the hydrological
cycle where WMO has a particular interest and responsibility in promoting the close coordination of the methods and activities of those involved in the two disciplines. In this context,
the Global Energy and Water Cycle Experiment (GEWEX) is noteworthy. The International
Association of Hydrological Sciences (IAHS) jointly convened with WMO a working group on
GEWEX. It was this Working Group that proposed the study of a large river basin, which
subsequently focussed on the Mississippi Basin in the form of the GEWEX Continental-scale
International Project (GCIP).
IHP and HELP
The International Hydrological Programme (IHP) is a UNESCO Natural Sciences Programme
that grew out of the International Hydrological Decade (IHD: 1965-75). Its purpose is to improve
the scientific and technological basis for the development of methods and the human resource
base for the rational management of water resources, including the protection of the
environment, and to integrate developing countries into the worldwide ventures of research and
training.
In February 1999, the 5th Joint UNESCO/WMO Conference on International Hydrology
unanimously endorsed a new global initiative, entitled HELP (Hydrology for Environment, Life
and Policy), which will establish a global network of catchments to improve the links between
hydrology and the needs of society. The overarching purpose of HELP is to deliver social,
economic and environmental benefit to stakeholders through sustainable and appropriate use of
water by deploying hydrological science in support of improved integrated catchment
management. Because the catchment is the natural unit of hydrology, HELP is specifically
catchment-based. However, HELP is people and environment centered, problem-driven and
demand-responsive: it takes questions of environment, life, and policy as the starting point and
hydrology as the vehicle for their solution. HELP therefore undertakes new interdisciplinary
studies at a range of appropriate scales that foster integrated solutions to a range of water
related environment, life, and policy problems. From the outset of the program, HELP has
involved physical and social scientists from the operational and research communities, water
policy experts, managers and users. Where expertise is lacking HELP will endeavor to create it
through education and capacity building. It addresses the following six global freshwater policy
issues: (a) water and food; (b) water quality and human health; (c) water and the environment;
(d) water and climate; (e) water and conflicts; (f) communication between hydrologists and
society.
At the global level, HELP is guided by a Steering Committee of international experts on waterrelated policy, management and science and representatives from partner organizations (e.g.
WMO, IAEA, IGBP, GEWEX, CLIVAR, IAHS, NGOs). The structure of HELP Regional
Coordinating Units (RCUs) is necessarily flexible to accord with local institutional arrangements,
most likely established in existing national or regional institution. Fundamentally, HELP is a
global network of catchments that benefit from communication between hydrologists and
stakeholders within and between participating basins. Benefits include knowledge of new
technologies of data acquisition and analysis and shared expertise, and the opportunity to
address existing and emerging conflicts through access to external expertise and experience in
conflict management, and by learning from the experience and body of knowledge from other
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HELP basins. To contribute to the HELP program, some catchment attributes are deemed
essential. HELP catchments must provide an opportunity to study a water policy or water
management issue for which hydrological process studies are needed, relevant national and
local agencies must agree to cooperate in the execution of HELP, there must be adequate local
capacity to participate in the program as a full partner, a minimum range of key variables and
parameters must be monitored, data, information and technological expertise must be shared
openly, and HELP data standards, quality assurance and quality control must be adhered to.
IGBP PROGRAMS
The International Geosphere Biosphere Programme (IGBP) was established in 1986 by the
International Council of Scientific Unions (ICSU). Its objective is “… to describe and understand
the interactive physical, chemical, and biological processes that regulate the total Earth system,
the unique environment that it provides for life, the changes that are occurring in this system,
and the manner in which they are influenced by human activities.” IGBP is an interdisciplinary
research endeavor. Like WCRP and other WMO activities, IGBP only rarely provides direct
funding for research, its primary function is to coordinate research and data collection activities
within cooperating countries. Emphasis is placed on the interactions of biological, chemical,
and physical processes that govern change in the Earth system and that are most susceptible to
human perturbation. IGBP has developed detailed plans for the conduct of science in its eleven
component Programme Elements. These are composed of eight broadly discipline-oriented
projects, covering such topics as atmospheric science, terrestrial ecology, oceanography,
hydrology, and links between the natural and the social sciences. Three IGBP “core projects:
are of particular interest to global water cycle research: Biospheric Aspects of the Hydrologic
Cycle (BAHC); Global Change and Terrestrial Ecosystems (GCTE); and Land-Use and LandCover Change (LUCC). They are described briefly below.
BAHC
The BAHC core project addresses the nature of the interaction between vegetation and the
hydrologic cycle. BAHC is an interdisciplinary project combining and integrating expertise from
many disciplines, in particular ecophysiology, pedology, hydrology, and meteorology. In this
respect BAHC cuts across disciplines as well as across spatial scales. At smaller scales, BAHC
is involved in developing techniques and algorithms to provide climatic data needed at the
scales of hydroecological research used to study changes of land surface conditions. At larger
scales, BAHC provides soil-vegetation-atmosphere transfer models, in particular, the areal
pattern of heat and moisture fluxes according to land-surface heterogeneity. BAHC is involved
in these activities in a number of selected areas in the world, representing major ecosystems.
GCTE
The GCTE core project aims to develop a predictive understanding of the effects of changes in
climate, atmospheric composition, and land use on terrestrial ecosystems (both natural and
managed), and to determine feedback effects to the atmosphere and the physical climate
system. Ecosystem responses are being investigated both through manipulative studies and
long-term studies at selected sites. The latter activity is being developed in collaboration with
the developing Global Terrestrial Observing System (GTOS). Modeling studies are focused on
the construction of dynamic vegetation and agricultural systems models at a variety of scales,
both for linking to global biogeochemical models and physically based GCMs and for direct
impact studies.
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LUCC
The LUCC core project is jointly sponsored by the International Human Dimensions Programme
(IHDP) on Global Environmental Change. It addresses how land use, and thus land cover and
surface properties, is affected by socio-economic factors, and aims to integrate the driving
forces of land-cover change into a global land-use and land-cover change model. The primary
objectives of LUCC are: to obtain a better understanding of global land-use and land-cover
driving forces; to investigate and document temporal and geographical dynamics of land-use
and land-cover; and to define the links between sustainability and various land uses. Over the
coming decades, the global effects of land use and land cover change (LUCC) may be as
significant, or more so, than those associated with potential climate change. Unlike climate
change per se, land use and cover change are known and undisputed aspects of global
environmental change. These changes and their impacts are with us now, ranging from
potential climate warming to land degradation and biodiversity loss and from food production to
spread of infectious diseases. LUCC´s significance notwithstanding, our understanding of the
scale and pace of this change, its human and biophysical origins, and its linkages to other
global change is inadequate. It is a testament to this paucity of knowledge that an accurate
global map of agriculture does not exist, that we do not have good measures of change in such
land covers as forests and grasslands, and that we cannot model and project well land-use and
cover changes in an integrative way.
IPCC
The Intergovernmental Panel on Climate Change (IPCC) is a joint activity of the WMO and the
United Nations Environment Programme (UNEP). IPCC was established in 1988, and is open
to all members of the UNEP and WMO. The charge of IPCC) is “to assess the scientific,
technical and socio-economic information relevant for the understanding of the risk of humaninduced climate change.” The IPCC provides scientific, technical and socio-economic advice to
the world community, and in particular to the 170-plus Parties to the UN Framework Convention
on Climate Change (UNFCCC) through its periodic assessment reports on the state of
knowledge of causes of climate change, its potential impacts and options for response
strategies. It does not carry out new research nor does it monitor climate-related data. It bases
its assessment mainly on published and peer reviewed scientific technical literature. The IPCC
has three working groups and a Task Force, of which Working Group I (scientific aspects of the
climate system and climate change) and Working Group II (vulnerability of socio-economic and
natural systems to climate change, and adaptation options) are most relevant to the U.S. water
cycle program..
Some of the questions being addressed by Working Group I to which the U.S. water cycle
program may be able to contribute are: How have precipitation and atmospheric moisture
changed in the recent past? Has climate variability or climate extremes changed, including
changes in the variability of droughts, wet spells, and hail? What is the nature and magnitude of
water vapor and cloud feedbacks? The necessity of fresh water to humans dictates that
Working Group II centrally addresses the possibility of changes in hydrologic conditions. Thus,
Working Group II will stand to benefit from progress made by the U.S. water cycle program in
furthering understanding of: the current state and potential changes in the hydrological cycle,
including precipitation, evaporation, runoff, soil moisture, groundwater, and extreme hydrological
events; and management implications and adaptation options, including responses to extreme
hydrological events.
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U.S. INTERAGENCY PROGRAMS
A number of US programs run collaboratively among two or more agencies currently contribute
to water cycle studies and research. As the U.S. water cycle program evolves, it is expected
that these existing water cycle efforts will be expanded and new ones will be developed to fill
identified gaps. A few aspects of these ongoing efforts are summarized below. The list is neither
comprehensive nor complete; rather it is intended to highlight a selected number of important
current and ongoing efforts.
GCIP/GAPP
NOAA and NASA have provided support for the ongoing GCIP project (currently slated to
terminate in 2001) and its successor, GAPP. The primary focus of GCIP is on the Mississippi
river basin, where the project aims to quantify the atmospheric energy and water budgets. GCIP
includes an operational pathway, which is designed to transfer GEWEX research results into
near real-time weather and climate forecasting activities. This is the so-called NOAA coreproject. A parallel (and larger) research phase addresses GCIP science goals, which include
development of better products from more comprehensive models and reanalyzed data later
from the basic research of the GCIP project. Among GCIP’s major contributions have been
improvements in NCEP’s regional data assimilation capabilities, and the ability to produce
consistent gridded fields of aerological and hydrological variables over the continental U.S. on a
systematic daily schedule. For the first time, these regional operational products are being
archived and distributed as a basic resource for investigations of coupled atmospheric and
hydrologic climate processes on spatial scales from local to continental and on time-scales from
hourly to interannual. GCIP has also facilitated integration of data from a range of sources,
including upper-air radiosondes, surface weather stations, rain gauges and stream gauges. It is
also assembling a five-year (1996-2000) research quality data set of precipitation radar (based
on NEXRAD WSR-88D), as well as supporting data from wind profilers, and automatic weather
stations. New observations of soil moisture have also been initiated under GCIP sponsorship,
and will become part of the nation's climatic information system.
Through GCIP’s research pathway, basic research has been sponsored that has lead to
characterization of the time and space variability of the energy and water budgets from
catchment to continental scales. Across the spectrum of scales relevant to atmospheric and
hydrological processes, GCIP has sponsored development of global and limited-area
atmospheric models and hydrologic models ranging from the highest feasible resolution to
regional or "macroscale". These models have been applied to estimate energy and water
budgets; and to develop information retrieval schemes that integrate existing and future satellite
observations and ground-based measurements. In addition, GCIP is also developing and
disseminating a comprehensive data base that includes in situ, model and remote sensing
information. Finally, GCIP has funded development of macroscale hydrological models,
applicable to large continental river basins like the major tributaries of the Mississippi. These
models have been used to predict the land surface water and energy budgets of the major
tributaries of the Mississippi, and have proved useful as a diagnostic tool for other water
balance assessments, based for instance on reanalysis data. GCIP received initial funding in
1994 to explicitly prepare a program of core and research activities (Lawford, 1999). GCIP is
now transitioning to a project covering the entire US and linking to the US CLIVAR PACS
program This GEWEX America Prediction Project (GAPP) is expected to be a central element
of the U.S. water cycle initiative.
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U.S. CLIVAR
The U.S. CLIVAR effort, which is the U.S. contribution to the international CLIVAR effort, is
designed to understand seasonal-to-interannual climate variability and predictions. Efforts in
decadal variability and anthropogenic change also have high priority. U.S. CLIVAR will have a
strong focus on decadal modulation of El Niño Southern Oscillation (ENSO), and seasonal-todecadal variability of the North Atlantic Oscillation. In the Pacific Sector, the Pan American
Climate Study (PACS) and the Variability of the American Monsoon System (VAMOS) programs
are under active development, and will be included within U.S. CLIVAR. The overall goal of
PACS is to advance the understanding of seasonal and longer time scale phenomena needed
to extend the scope and skill of climate prediction over the Americas, with emphasis on warm
season precipitation. PACS is concentrating on the north American monsoon, including the
structure and variability of the continental scale mode and the mechanisms that generate warm
season precipitation anomalies. PACS is specifically concerned with explaining climatological
characteristics of the atmospheric hydrologic cycle, including the relationship of the eastern
Pacific coastal stratus and the continental precipitation as well as the influence of the land and
ocean surface on seasonal predictability. U.S. CLIVAR activities are further linked with World
Weather Watch (WWW), the Global Climate Observing System (GCOS), the Global Ocean
Observing System (GOOS), and the Global Ocean Data Assimilation Experiment (GODAE), the
Global Energy and Water Cycle Experiment (GEWEX) and Past Global Changes (PAGES). Of
particular interest to this water cycle initiative are the CLIVAR and GEWEX effort to develop
surface fluxes, including evaporation from in situ observations and satellite measurements. In
addition, understanding the role of the oceans in the global water cycle variability will be critical
for climate predictability of the water cycle.
EOS
The Earth Observing System (EOS), in planning since the 1980s, is a NASA program (with
national and international collaborators) which has entered a new stage with the launch of Terra
(formerly known as EOS-AM) in December, 1999. A significant part of the EOS program is
focused on observation of atmospheric and land surface phenomena, with the goal of better
understanding the dynamics of the Earth’s physical climate. NASA has been a major supporter
of field projects, modeling, and data assimilation activities aimed at better representing the
coupled land-ocean-atmosphere system These studies have included, for instance, intensive
field campaigns like FIFE, the BOReal Ecoysystem-Atmosphere Study, and LBA, which
integrated in situ observations with aircraft and satellite remote sensing. The International
Satellite Land Surface Climatology Project (ISLSCP) has had major support from NASA. NASA
also provides data products and analyzed fields essential to the success of GCIP, notably
diagnostics of cloud amount and properties through the International Satellite Cloud Climatology
Project (ISCCP), surface radiation flux estimates (Langley Research Center) and
soil/hydrology/vegetation data (Huntsville Global Hydrology and Climate Center). Conversely, it
is expected that GCIP multi-disciplinary studies and data products will provide a high quality
benchmark for the validation of EOS observations for Terra, EOS-PM, and other missions like
the Tropical Rainfall Monitoring Mission (TRMM).
USWRP
The U.S. Weather Research program (USWRP) provides a research focus for the ongoing
modernization of the National Weather Service. USWRP is attempting to improve the specificity,
accuracy, and reliability of weather forecasts using the best possible mix of modern
observations, data assimilation, and forecast models. In particular, USWRP's goal is to improve
forecasts of high impact weather for agriculture, construction, defense energy, transportation,
public safety (emergency management), and water resource management, including floods.
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USWRP is especially concerned with studies related to quantitative precipitation forecasting.
These include the measurement, estimation and depiction of water vapor, representation of
convection in forecast models and estimation of precipitation amount and type and by radar and
satellite. USWRP has also begun to consider the control on extreme events by surface effects,
including soil/vegetation and canopy. These weather prediction research efforts complement
GCIP's regional climate activities. In addition, USWRP's studies related to quantitative
precipitation forecasting will help GCIP understand how to make better use of NEXRAD
products. The USWRP is also beginning to coordinate its activities with the World Weather
Research Programme, which is currently exploring a formal linkage with GEWEX through
WMO/WCRP.
U.S. NATIONAL ASSESSMENT
The National Assessment of Potential Consequences of Climate Variability and Climate Change
(“U.S. National Assessment”) was called for by the 1990 Federal Climate Change Act. The first
assessment was initiated in 1998, and is currently nearing completion. It consists of regional
assessment reports for eight regions of the U.S., sector reports for agriculture, water, human
health, coastal and marine resources, and an overview report. Some of the regional reports
have been released in draft or final form, and the sector and overview reports have recently (or
are about to be as of this writing) released for public comment.
The National Assessment was conducted by a large group of researchers and practitioners.
Primary responsibility for each of the regions and sectors was assigned to a federal agency
(e.g., NOAA was the lead agency for the Pacific Northwest report, while the U.S. Geological
Survey took the lead for the water sector report). The summary document was written by the
National Assessment Synthesis Team and a set of lead authors, who were drawn from the
private and public sectors, and a range of disciplines.
The current assessment is the first of what is expected to be a continuing activity, somewhat
parallel in function and construct to the IPCC on the international level. The National
Assessment is not expected to be a research activity, rather it is intended to report on the
current understanding of “what we presently know about the potential consequences of climate
variability and change for America in the 21st Century”.
OTHER US PROGRAMS
The cooperating agencies within USGCRP all have some interest in water resources. Thus,
there are a number of research efforts within agencies that can contribute to a coordinated
water-cycle initiative. Again, the list below is neither complete nor comprehensive, but
represents a sample of ongoing programs.
National Aeronautic and Space Agency (NASA)
The mission of NASA's Earth Science Enterprise (ESE) is to develop a scientific understanding
of the Earth system and its response to natural or human-induced changes and improve
prediction capabilities for climate, weather, water resources, the Earth’s ecosystems, global air
quality and natural hazards. To this end, the Earth science research program seeks a deep
understanding of Earth system components and their interactions ranging from short-term
weather to long-term climate time scales, and from local and regional to global space scales.
ESE is driven by the recognition of the impact of the natural variability of the planetary
environment on society, and the realization that humans are no longer passive participants in
the evolution of the Earth system, a view shared by the world's scientific authorities. The
strategic objective of the Enterprise is to provide the scientific basis and answers to the
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overarching question: “How is the Earth changing and what are the consequences for life
on Earth?” Particular attention is placed on: forcings, responses, and the processes that link
the two and/or constitute feedback mechanisms.
ESE’s research maps across the broad themes of the USGCRP addressing the need to better
understand: the Earth’s climate system on all time scales; the composition and chemistry of the
Atmosphere; the global water cycle; ecosystems and the global carbon cycle; the human
dimensions of global change; and the geological history of environmental change (slow physics
processes). ESE’s research efforts emphasize, but are not limited to, space-based studies of
the Earth as an integrated system. All of ESE’s programs contribute directly or indirectly to the
GCRP Water Cycle initiative and, in particular, the Enterprise’s Global Water and Energy Cycle
(GEWEC) program. The main science questions addressed by GEWEC are:
Is the global cycling of water through the atmosphere accelerating?
What are the effects of clouds and surface hydrologic processes on climate change?
How are variations in local weather, precipitation and water resources related to global
climate change?
To what extent can weather forecasting be improved by new global observations and
advances in satellite data assimilation?
The satellites developed and launched under the auspices of NASA’s Earth Observing System
(EOS) contribute directly to GEWEC and the USGCRP Water Cycle Program; in particular:
TRMM, EOS-Terra, EOS-Aqua, and others. NASA is currently in the planning stages for new
space-borne missions in the post-EOS era (roughly 2002-2010). Among the mission concepts
being considered are sensor packages that would support scientific investigations in surface
water hydrology, global precipitation, soil moisture, and cold season processes. All of these
missions, as well as currently planned cloud and radiation sensors and various current and
planned land cover missions, are directly applicable to the water cycle science plan.
National Oceanic and Atmospheric Administration (NOAA)
In addition to is lead role with respect to the GCIP/GAPP program, NOAA, through its Office of
Global Programs, supports integrated scientific assessments of the effects of climate variability
and change on the natural and managed environment. These continuing projects are designed
to characterize the state of knowledge of climate variations and changes at regional scales, to
identify knowledge gaps and linkages in selected climate-environment-society interactions, and
to provide an informed basis corresponding to climate-related risks. At present, there are five
regional integrated science and assessments activities funded by NOAA-OGP. These are
focused on the Pacific Northwest, the Southwest, California, Inter-Mountain West, and the
Southeast regions of the United States. In addition, NOAA-OGP's Human Dimensions program
supports research projects on the institutional capacity of water management agencies to plan
for climate variability and respond to forecast information. Projects analyze the use of climate
and hydrologic information in the context of competing uses for water, transboundary resource
management issues, and the ability of water markets, adaptive management, and other
mechanisms to enhance the efficiency of water management in the face of global change. The
NOAA Paleoclimatology Program and World Data Center for Paleoclimatology serve as a
national and international catalyst for understanding and modeling interannual to century-scale
environmental variability. In the case of the water cycle, paleoclimatology provides an array of
relevant information on scales from variability of global scale climate that influences regional
hydroclimate, to reconstructions of regional drought over centuries to millennia, to annual
reconstructions of past seasonal streamflow within a watershed.
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Within the National Weather Service Office of Hydrology (NWS/OH), the Advanced Hydrological
Prediction System (AHPS) is seeking to improve the state of the art of hydrologic prediction as
applied primarily to flood forecasting. Although NWS/OH does not formally support extramural
research, it is cooperating with the academic community in the development of AHPS, in
particular through an evolving partnership with GCIP/GAPP. Also in NWS, the Environmental
Modeling Center (EMC) and Climate Prediction Center (CPC) of the National Centers for
Environmental Prediction (NCEP) develop and execute retrospective (multi-decade) and
realtime climate monitoring and prediction systems. These monitoring and prediction systems
include a) the coupled ocean/atmosphere modeling system with its ocean data assimilation
system, b) the retrospective 50-year atmospheric Global Reanalysis and its realtime monitoring
counterpart, and c) the retrospective 25-year coupled land/atmosphere Regional Reanalysis
program and its realtime Eta Data Assimilation System, retrospective and realtime Land Data
Assimilation System (LDAS) and companion reanalysis of daily U.S. precipitation.
National Science Foundation (NSF)
The National Science Foundation (NSF) supports a broad range of disciplinary and
interdisciplinary research in the geosciences that is related to various aspects of the water
cycle. NSF has supported water cycle research under the Water and Energy: Atmospheric,
Vegetative, and Earth Interactions (WEAVE) initiative, through special competitions under
Biocomplexity in the Environment, and through its core programs. Currently, an Environmental
Research and Education initiative is being developed which will include research foci
addressing water and biogeochemical cycles. The program will stress the interconnectedness
of earth, atmospheric and biological systems and the dynamics of coupled natural and human
systems.
Department of Energy (DOE)
The Department of Energy funds the Atmospheric Radiation Measurement (ARM) program that
is intended to improve understanding of the transfer of radiation through the atmosphere. A
central ARM component is the Cloud and Radiation Testbed (CART) concept, which is currently
underway at sites in the Southern Great Plains (SGP) of south central Kansas and central
Oklahoma, the North Slope of Alaska, and a Tropical Western Pacific site. The CART sites
provide surface radiation flux data, as well as boundary layer soundings, at multiple observing
locations. Enhanced observations are collected during Intensive Observation Periods (IOP) of a
few weeks duration during each year. At the SGP CART site, observations are coordinated with
GCIP studies of summer rainfall and re-evaporation. In addition, the Atmospheric Boundary
Layer Experiments (ABLE) facility located in the SGP CART site is well suited for studies of the
hydrological balance and associated processes in a closed catchment. ABLE has hosted two
field campaigns carried out by the Cooperative Atmosphere-Surface Exchange Study
consortium.
The Walker Branch Watershed is located on the U. S. Department of Energy's Oak Ridge
Reservation in Anderson County, Tennessee. The 100 ha Walker Branch Watershed is an
instrumented forest watershed research site with 30 year history of research and modeling of
forest ecology, stream ecology, hydrology, and biogeochemistry. The site conducts long-term
measurements for forest ecology, stream ecology, biogeochemistry, and watershed hydrology.
The site supports several long-term experiments. Research priorities include biogeochemical
cycling, pollutant deposition, climate change, forest productivity, and biodiversity. The
watershed is currently home to an Ameriflux installation managed by NOAA for DOE and the
Throughfall Displacement Experiment – a large-scale manipulation to understand the potential
impact of precipitation changes on forested ecosystems.
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United States Department of Agriculture (USDA)
Agricultural Research Service (USDA-ARS)
The Agricultural Research Service(ARS) of USDA conducts fundamental hydrologic research in
support of aspects of its mission related to management of agricultural crop and range lands.
One aspect of the ARS research program of particular interest to this water cycle science plan is
its national network of instrumented experimental watersheds and field research facilities. The
program consists of 12 intensively instrumented catchments across the U.S., and over 140 less
intensively monitored sites, some of which have operated continuously since the 1930s.
Additionally, hydrometeorological measurements exist for experimental rangeland areas
extending back to 1915. The ARS provides public access to the watershed data for all
hydrologic researchers.
Forest Service (USDA-FS)
The USDA-FS supports hydrologic cycle and related research on forested watersheds as part of
its mission to sustain the health, diversity, and productivity of the nation’s forests and
grasslands. The watershed research program is managed at 34 locations, with studies
conducted on a nationwide network of experimental forests and watersheds. Six sites
(Baltimore, Bonanza Creek, Coweeta, H.J. Andrews, Hubbard Brook, Luquillo) are intensive
research sites within the NSF LTER Program. Current program components focus on
developing the science base to manage and restore watershed and riparian ecosystems,
assess effects of forest roads on streamflow and erosion, protect municipal water supplies,
evaluate effects of air pollutants and urbanization on water quality, rehabilitate watersheds
following wildfire, and contribute to integrated ecological and hydrologic studies at LTER sites.
Ongoing studies focus on global change impacts on forest ecosystems and watersheds,
including development of national and regional models to evaluate ecological, hydrologic, and
economic impacts of climate change.
U.S. Geological Survey (USGS)
The USGS carries out a broad program of monitoring, data collection, and investigations in
water resources, biological resources, mapping, and geology. Results relevant to the global
water cycle include archives of US streamflow, ground-water, and water-quality data; maps and
digital geospatial data, including digital elevation models, digitized stream networks, and
drainage divides; archives of land remote-sensing imagery and derived products; and models
and syntheses of information about regional hydrologic systems throughout the US. Through its
Water, Energy, and Biogeochemical Budgets (WEBB) Program, the USGS supports five sites
that, in collaboration with scientists from universities and other Federal and State agencies, are
used to investigate watershed processes, including the effect of atmospheric and climatic
variables. In addition, through the National Research Program (NRP), other National programs,
and District offices, the USGS conducts research in support of its mission of characterizing the
quality and quantity of the Nation's water resources. Among research relevant to this initiative
are NRP's studies into the processes that govern the sources, sinks, and transport of carbon
and nitrogen, research on the chemistry, microbiology, and movement of water, solutes, and
gases in porous and fractured materials and in the unsaturated zone, and studies on the
interaction of ground water and surface water. The USGS also supports a small extramural
research program that provides funds to the 54 Water Resources Research Institutes and other
universities.
The National Research Program (NRP) of the USGS conducts hydrologic research in support of
its mission responsibilities relative to characterization of the water resources of the U.S.. The
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NRP is designed to encourage pursuit of a diverse agenda of research topics aimed at providing
new knowledge and insights into land surface hydrologic processes that are not well
understood, and which involve both water quantity and water quality. The emphasis of the NRP
evolves through time, and reflects the emergence of new areas of inquiry and the potential for
new tools and techniques. In addition to its research programs, the USGS carries out a broad
program of monitoring, data collection, and investigations in water resources, mapping, geology,
and biological resources. Results relevant to the global water cycle include archives of US
streamflow, ground-water, and water-quality data; maps and digital geospatial data, including
digital elevation models and digitized stream networks and drainage divides; archives of land
remote-sensing imagery and derived products; and models and other syntheses of information
about regional hydrologic systems throughout the US.
U.S. Environmental Protection Agency (EPA)
EPA’s Global Change Research Program is conducting assessments of the consequences of
global change (changes in climate, landuse, and UV radiation). The program’s Water Quality
focus area examines how changes in the hydrologic cycle might affect the ability of water
resource managers to meet water quality standards. In particular, EPA is studying the possible
impacts on drinking water treatment and quality, wastewater treatment requirements, and
surface water quality. The Human Health focus area is examining changes in the incidence of
water-borne diseases, while the Ecosystems focus area is exploring impacts of changes in
water quantity and quality on aquatic ecosystem health.
US Army Corps of Engineers (USACE)
The U.S. Army, through its Army Research Office (ARO), supports basic research designed to
advance scientific and technological knowledge for enhancing army capabilities. ARO's
terrestrial science program sponsors academic research in the broad area of land-atmosphere
processes which includes the hydrologic regime.
The Army Corps of Engineers, through its Engineer Research and Development Center
(ERDC), Institute for Water Resources (IWR), and Hydrologic Engineering Center (HEC),
conduct significant applied research focused on more effective decision making for water
resource management. This includes a major focus on coupled physical and ecological process
simulation at system-wide (watershed) scales, regional sediment management, innovative flood
protection, water control infrastructure rehabilitation, coastal storm protection and environmental
risk assessment. Much of this research is accomplished in conjunction with the academic
community and in concert with the related initiatives of other federal agencies. Climate change
and the effects of climate variability have this far not been a specific research focus area,
however, the Corps has participated in studies and technical forums concerning those issues.
The Corps remains highly interested in this area and the value of new knowledge to the overall
execution of our mission in the future.
Bureau of Reclamation (BoR)
The Bureau of Reclamation’s (Reclamation) mission is to manage, develop and protect our
planet’s most valuable natural resource - water, and related resources in an environmentally
and economically sound manner in the interest of the American public. As the primary resource
management agency responsible for managing 350 major dams from Grand Coulee in the
Columbia Basin to Hoover Dam in the Colorado River Basin, Reclamation serves over 100
million Americans. Reclamation supports applied science and technology to develop and
improve science based decisions for reservoir and river system operations. Reclamation’s water
resource managers are charged with balancing the allocation of limited water supplies among
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competing needs for agriculture, municipal and industrial users, while maintaining the quality of
riparian habitat for fish, recreation and cultural activities.
Reclamation’s Science and Technology Program conducts research related to water and water
resource management, watershed modeling, water quality, ecosystem and riparian habitats,
precipitation forecasting, delivery system enhancements, and technology research and
development that will lead to improvements in water delivery and riverine ecosystems.
Reclamation’s science program seeks to integrate emerging practical technologies like those
proposed in the Water Cycles Initiative into its operations through the Watershed and River
System Management Program. This program serves water operations managers in the
Colorado, Yakima, Rio Grande, and Truckee River Basins, and it provides state-of-technology
links to National Weather Service river forecasts, WSR-88D precipitation estimates, USGS
stream gage and watershed runoff forecasts, and other water supply and demand information.
WEB SITES
There are numerous traditional publications associated with each of the programs listed above.
However, rather than try to list all relevant documents, we instead list the main web site for each
program. These web sites should be used as the starting point to find far more information than
would be normally available from a single traditional publication.
SELECTED INTERNATIONAL PROGRAMS
ACSYS: http://www.npolar.no/acsys/
BAHC: http://www.pik-potsdam.de/~bahc/
CLIVAR: http://www.dkrz.de/clivar/hp_nf.html
GCOS: http://www.wmo.ch/web/gcos/gcoshome.html
GCTE: http://www.igbp.kva.se/gcte1.html
GEWEX: http://www.gewex.com
HWRP: http://www.wmo.ch/web/homs/hwrphome.html
HELP: http://www.unesco/science/help
IGBP: http://www.igbp.kva.se/progelem.html
IHP: http://www.nfr.se/internat/ihp_igbp/IHPindex.html
LUCC: http://www.igbp.kva.se/lucc.html and http://www.uni-bonn.de/ihdp/lucc/
SPARC: http://www.aero.jussieu.fr/~sparc/introduction.html
WCRP: http://www.wmo.ch/web/wcrp/wcrp-home.html
WMO: http://www.wmo.ch/
WOCE: http://www.soc.soton.ac.uk/OTHERS/woceipo
SELECTED US NATIONAL PROGRAMS
ARM: http://www.arm.gov/
EOS: http://eospso.gsfc.nasa.gov/
GCIP/GAPP: http://www.gewex.com/gcip.html
U.S. CLIVAR: http://www.clivar.ucar.edu/hp.html
USDA-ARS: http://www.nps.ars.usda.gov/programs/201s2.htm
USGS-NRP: http://water.usgs.gov/nrp/
USWRP: http://box.mmm.ucar.edu/uswrp/
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APPENDIX D – CROSS-LISTINGS BETWEEN PILLAR
INITIATIVES AND SCIENCE ELEMENTS
PILLAR INITIATIVE #1-Determine whether or not the global water
cycle is accelerating and to what degree human activities are
responsible.
CATEGORY
Observations
Process studies
Modelling
Budget studies
INITIATIVE
Chapter 2, 5.1.1
Chapter 2, 5.1.2
Chapter 2, 5.1.3
Chapter 3, 5.3.1
Chapter 2, 5.1.8
Chapter 3, 5.3.2
Chapter 2, 5.2.1
Chapter 2, 5.2.2
Chapter 2, 5.2.5
Chapter 2, 5.2.6
Chapter 2, 5.3.1
Chapter 2, 5.4.5
Chapter 3, 5.1.1
Chapter 3, 5.1.2
Chapter 2, 5.5
BRIEF DESCRIPTION
Water vapor
Clouds and radiation processes
Global precipitation
Snow and ice
Global ocean fluxes
Field water-vapor experiments
Campaign for precipitation and cloud microphysics
Field experiments of connections among atmosphere, land, and ocean
processes.
Multi-year field measurements to distinguish slow and fast processes
Improve models
Reanalysis
Determine optimal modelling strategies
Observing system simulation
Evaluate observed and computed budgets
Table D.1 - Components of pillar initiative 1. This pillar initiative includes specific
initiatives described in Sections 5 of Chapters 2 and 3. The chapter initiatives in
bold italic are essential priorities, others are supporting priorities.
PILLAR INITIATIVE #2-Determine the deeper scientific understanding
that is needed to reduce substantially the losses or costs associate
with water-cycle calamities such as droughts, floods and coastal
eutrophication.
CATEGORY
Observations
Process studies
Modelling
Knowledge
transfer
INITIATIVE
Chapter 2, 5.1.3
Chapter 3, 5.3.1
Chapter 2, 5.1.4
Chapter 2, 5.1.5
Chapter 2, 5.1.6
Chapter 2, 5.1.7
Chapter 2, 5.1.8
Chapter 3, 5.3.2
Chapter 3, 5.3.3
Chapter 4, 5.3.1
Chapter 4, 5.3.2
Chapter 4, 5.2
Chapter 2, 5.2.1
Chapter 2, 5.2.2
Chapter 2, 5.2.3
Chapter 2, 5.2.4
Chapter 2, 5.2.5
Chapter 2, 5.2.6
Chapter 4, 5.4.1
Chapter 2, 5.3.1
Chapter 2, 5.3.2
Chapter 2, 5.4.1
Chapter 2, 5.4.2
Chapter 2, 5.4.3
Chapter 3, 5.1.1
Chapter 3, 5.1.2
Chapter 3, 5.1.3
Chapter 4, 5.5.1
Chapter 4, 5.5.3
Chapter 2, 5.6
Chapter 3, 5.1.4
Chapter 3, 5.6
Chapter 4, 5.6
BRIEF DESCRIPTION
Precipitation
Evaporation and energy fluxes
Surface runoff
Groundwater
Soil moisture
Snow and ice
Global ocean fluxes
Fluxes among atmosphere, surface, and subsurface reservoirs
Fluxes of water, nitrogen, and carbon at mouths of major rivers
Remote sensing for ecosystem parameters in fresh waters
Enhance measurements associated with carbon science effort
Field water-vapor experiments
Campaign for precipitation and cloud microphysics
Land-atmosphere field experiments
Cold seasons field experiments
Field experiments of connections among atmosphere, land, and ocean
processes.
Multi-year field measurements to distinguish slow and fast processes
Nested basin studies
Improve models
Coordinated model experiments
Atmosphere 4DDA
Ocean 4DDA
Land 4DDA
Determine optimal modelling strategies
Observing system simulation
Develop new theory
Coupled water-nitrogen-carbon models
Develop dynamic vegetation models
Promote knowledge transfer among scientists and stakeholders
Table D.2 - Components of pillar initiative 2. This pillar initiative includes specific
initiatives described in Sections 5 of Chapters 2-4. The chapter initiatives in bold
italic are essential priorities, others are supporting priorities.
PILLAR INITIATIVE #3-Develop the scientifically-based capacity to
predict the effects of changes in land use, land cover and
cryospheric processes on the cycling of water and important
biogeochemical constituents.
CATEGORY
Observations
Process studies
Modelling
Budget studies
Knowledge
transfer
INITIATIVE
Chapter 2, 5.1.3
Chapter 3, 5.3.1
Chapter 2, 5.1.4
Chapter 2, 5.1.5
Chapter 2, 5.1.6
Chapter 2, 5.1.7
Chapter 2, 5.1.8
Chapter 3, 5.3.3
Chapter 4, 5.3.1
Chapter 4, 5.3.2
Chapter 4, 5.3.3
Chapter 4, 5.1
Chapter 4, 5.2
Chapter 2, 5.2.3
Chapter 2, 5.2.4
Chapter 2, 5.2.6
Chapter 3, 5.2
Chapter 4, 5.4.1
Chapter 2, 5.3.1
Chapter 2, 5.3.2
Chapter 2, 5.4.6
Chapter 3, 5.1.1
Chapter 3, 5.1.2
Chapter 3, 5.1.3
Chapter 4, 5.5.1
Chapter 4, 5.5.3
Chapter 2, 5.5
Chapter 2, 5.6
Chapter 3, 5.1.4
Chapter 3, 5.6
Chapter 4, 5.6
BRIEF DESCRIPTION
Precipitation
Evaporation and energy fluxes
Surface runoff
Groundwater
Soil moisture
Snow and ice
Fluxes among atmosphere, surface, and subsurface reservoirs
Fluxes of water, nitrogen, and carbon at mouths of major rivers
Remote sensing for ecosystem parameters in fresh waters
Enhance streamflow and water-quality monitoring
Develop an integrated water-nitrogen-carbon data base
Develop measurement sensors for in situ measurements
Land-atmosphere field experiments
Cold seasons field experiments
Multi-year field measurements to distinguish slow and fast processes
Link process studies to systems model framework
Nested basin studies
Improve models
Coordinated model experiments
Sea ice 4DDA
Determine optimal modelling strategies
Observing system simulation
Develop new theory
Coupled water-nitrogen-carbon models
Develop dynamic vegetation models
Evaluate observed and computed budgets
Promote knowledge transfer among scientists and stakeholders
Table D.3 - Components of pillar initiative 3. This pillar initiative includes specific
initiatives described in Sections 5 of Chapters 2-4. The chapter initiatives in bold
italic are essential priorities, others are supporting priorities.