HYDROLOGIC APPLICATION PROJECT (HAP)
Reporting Period: October 2006 - September 2007
Project Starting Date: Spring 2006
URL: http://hydrology.princeton.edu/HAP (available soon)
Chair: Eric F Wood (2006-2009)
1. Overview:
The Hydrologic Prediction Project (HAP), beginning in the spring of 2006, aims to foster
and develop the science behind skillful ensemble hydrologic seasonal forecasts, and
demonstrating their usefulness. It is closely related to CEOP goals in that one research
focus of CEOP is to assist GEWEX in “demonstrating skill in predicting variability in
water resources and soil moisture on seasonal to annual as an element of WCRP's
prediction goals for the climate system.”
HAP will contribute to CEOP by focusing on scientific issues related to assessing current
hydrological conditions (nowcasting) and determining the extent to which seasonal
hydrological prediction is possible and useful for water resources. The previous project
WRAP had a focus on interactions with water resources managers within Regional
Hydrometeorological Project (RHP), while HAP will be focused more on developing and
testing procedures and methodologies for demonstrating skill in seasonal prediction and
estimating current hydrologic conditions – goals more consistent with GEWEX and
WCRP. Thus, HAP represents the direction for water management activities within
CEOP.
The HAP activities include:

developing procedures for assessing current hydrologic conditions, like water
availability and drought assessment, through application of GEWEX supported
data products, including remotely sensed observations;

developing and testing of reliable, skillful hydrologic ensemble forecast
procedures based on seasonal climate model forecasts;

demonstrating that the procedures can be applied at scales useful for water
resources through test-bed sites and demonstration projects, especially in close
collaboration with test-bed projects of the Hydrolologic Ensemble Prediction
Experiment (HEPEX) and the Global Water System Project (GWSP). HAP has a
primary role in fostering links between GEWEX and HEPEX, and GEWEX and
GWSP, and to provide leadership to help HEPEX and GWSP contribute to
GEWEX goals.

working with related CEOP projects, like WISE, and GEWEX-affiliated groups
like the International Association of Hydrological Sciences (IAHS), including the
IAHS Project for Ungauged Basins (PUB) to share demonstration project sites,
supporting data sets and approaches and results to further the project goals.
2. Status in 2007
Key progresses:
Progress has been made in forming the HAP seasonal forecasting working group. Over
the last project year, the HAP seasonal forecasting working group, whose focus is on the
methodological development of hydrological seasonal forecasting (downscaling, bias
corrections, evaluation of hindcasts and proper inclusion of forecast uncertainty), was
devoted to developing the nowcasting/prediction framework. Progress is made in the
following areas:

Test-bed projects. Several new test-bed projects were organized by HEPEX in
collaboration with HAP. Some of these are located in areas of interest to the U.S.
Regional Hydrometeorological Projects (RHP), But links between HAP/HEPEX
test-bed projects and some of the RHPs need to be strengthened.

Hydrologic nowcasting. The forecasting working group is developing procedures
for assessing current hydrologic conditions through the application of
NOAA/GEWEX supported NLDAS data products for the conterminous U.S.

Seasonal Hydrologic Predictions. The forecasting working group is developing
methodologies to predicting hydrologic conditions at seasonal scales.
Experimental forecast systems are being tested for conterminous U.S., China,
Africa and Brazil.

Drought Monitoring/Prediction. Based on the procedures developed for
hydrologic nowcasting/forecasting, the forecasting working group is developing
an integrated Drought Monitoring and Prediction System (DMAPS) and
conducted case studies for the severe 2007 droughts over the South East U.S. test
bed to determine the extent of the usefulness of the system. In the area of global
drought, HAP will collaborate with the WISE activities in CEOP, and wit outside
groups like UNESCO (IHP and IAHS). HAP would like to develop a strategy
with GEWEX where the drought monitoring activities can contribute to GEO.

Interaction with water management sector. Most of the HAP/HEPEX test-bed
projects include collaboration with users. One of these is led by a private sector
consulting firm (HYDROCOMP) that is applying hydrologic ensemble forecasts
at all time scales for major water resources clients in the western US. The
Southeastern U.S. HAP/HAPEX testbed has established collaboration with
Professsor Aris P. Georgakakos [Georgia Tech] on addressing water resources
management issues by using forecasting products from downscaled seasonal
climate models via the method developed by the HAP forecasting working group.
Such collaboration serves as a good example of infusing science into decision
making sector. HAP needs additional collaboration, which must be organized
through the CEOP RHPs and with groups like HEPEX.

Rescaling and downscaling atmospheric forecasts. Several HAP/HEPEX test-bed
projects have developed and are testing procedures. Prototypes are being
developed and integrated into operational and experimental hydrologic ensemble
forecast systems. Requirements for atmospheric ensemble hindcasts are being
studied.

Hydrologic hindcasting Procedures for hydrologic hindcasting are being
developed in some HAP/HEPEX test-bed projects. User-requirements for
hydrologic hindcasts are being developed. Hydrologic hindcast requirements are
expected to lead to major new requirements for atmospheric ensemble hindcasts.

Hydrologic uncertainty and post-processing Several HAP/HEPEX test-bed
projects are beginning to develop techniques to characterize hydrologic
uncertainty and to apply these in post-processing systems to correct bias and
spread problems in hydrologic ensemble forecasts.

Hydrologic modeling Water resources application of weather and climate
information requires the ability to quantify how this information will affect future
Streamflow in both large and small rivers throughout the world. This requires as
arsenal of hydrologic models that have been proven to be able to do this with the
information available locally to apply them to this problem. There is compelling
evidence for hydrologic prediction, as is already demonstrated for atmospheric
prediction, that a multi-model approach will both increase prediction skill as well
as reliability in the estimation of uncertainty in the predictions. Steady progress is
being made, as evidenced by many of the references cited below. But increased
attention to supporting data set development is needed, including support related
to the CEOP references sites, the CEOP RHP’s and support from IAHS activities.

Ensemble precipitation analysis of observations The most important single
observation required for hydrologic prediction is precipitation. This is also an
extremely difficult variable both to predict for the future and to estimate at scales
appropriate for hydrologic models from observations based on in-situ, radar and
satellite sensors. Hydrologic models, because of their nonlinearity, are highly
sensitive to the uncertainty in initial conditions that results from uncertainty in
recent precipitation forcing. An optimal, expected value estimate of precipitation
forcing when used as an input to [even a perfect] hydrologic model does not
produce an optimal, expected value of streamflow response. In general, it will be
too low because the uncertainty in the actual precipitation forcing must also be
considered. Larger events that possibly may have occurred would produce a
higher fraction of runoff than smaller events. This is becoming recognized in the
hydrologic community as an important issue that is especially important in
sparsely gauged areas where satellite-based precipitation estimates are especially
important. Therefore a HAP/HEPEX test-bed project was initiated in 2007 to
address this problem.

Collaboration with GEO/GEOSS, HAP and HEPEX are collaborating to
contribute to GEO/GEOSS through GEO water activity WA-06-02. This
collaboration can be strengthened by further collaboration with GEO water
activities that are being supported by the Asian Water Cycle Initiative.
List of Key Publications related to HAP:
Many papers related to the methodological development of the seasonal hydrologic
forecasting and related application studies were either published or submitted in peer
reviewed journals by investigators collaborating with HAP, HEPEX and IAHS activities
important to achieving the water resource objectives of GEWEX. These include:
Li, H., L Luo, E.F. Wood, 2007: Predicting Hydrologic Extremes Using Seasonal Hydrologic Forecast
System, A case study for the 2007 lowflows for the Eastern U.S. Atmospheric Science Letters (in
review)
Schaake, John C., Thomas M. Hamill, Roberto Buizza, and Martyn Clark HEPEX: The Hydrological
Ensemble Prediction Experiment Bulletin of the American Meteorological Society 88(10),October
2007, pp. 1541–1547
Andrew W. Wood _and John C. Schaake Correcting errors in streamflow forecast ensemble mean and
spread J Hydrometeology (in press) 2007.
A special issue of Atmospheric Sciencies Journal with papers from the 2007 HEPEX workshop will be
published in 2008.
IAHS 2006 Large Sample Basin Experiments for Hydrological Model Parameterization: Results
of the Model Parameter Experiment – MOPEX Edited by Vazken Andréassian, Alan Hall,
Nanée Chahinian & John Schaake IAHS Publication 307 (2006) I978-1-901502-73-2 348+
iv pp, plus a DVD with data
IAHS (2007) Quantification and Reduction of Predictive Uncertainty for Sustainable Water
Resources Management Edited by E. Boegh, H. Kunstmann, T. Wagener, A. Hall, L.
Bastidas, S. Franks, H. Gupta, D. Rosbjerg & J. Schaake IAHS Publ. 313 (2007) ISBN 9781-901502-09-1 528 pp.
Luo L., E. F. Wood, M. Pan (2007), Bayesian merging of multiple climate model forecasts for seasonal
hydrological predictions, J. Geophys. Res., 112, D10102, doi:10.1029/2006JD007655.
Luo L., E. F. Wood (2007), Monitoring and predicting the 2007 U.S. drought, Geophys. Res. Lett., 34,
L22702, doi:10.1029/2007GL031673.
Luo L., E. F. Wood (2006), Assessing the idealized predictability of precipitation and temperature in
the
NCEP
Climate
Forecast
System,
Geophys.
Res.
Lett.,
33,
L04708,
doi:10.1029/2005GL025292.
Hamlet A. F., D. P. Lettenmaier (2007), Effects of 20th century warming and climate variability on
flood risk in the western U.S., Water Resour. Res., 43, W06427, doi:10.1029/2006WR005099
Adam J. C., I. Haddeland, F. Su, D. P. Lettenmaier (2007), Simulation of reservoir influences on
annual and seasonal streamflow changes for the Lena, Yenisei, and Ob' rivers, J. Geophys. Res.,
112, D24114, doi:10.1029/2007JD008525.
Slater A. G., T. J. Bohn, J. L. McCreight, M. C. Serreze, D. P. Lettenmaier (2007), A multimodel
simulation of pan-Arctic hydrology, J. Geophys. Res., 112, G04S45, doi:10.1029/2006JG000303.
Su F., J. C. Adam, K. E. Trenberth, D. P. Lettenmaier (2006), Evaluation of surface water fluxes of the
pan-Arctic land region with a land surface model and ERA-40 reanalysis, J. Geophys. Res., 111,
D05110, doi:10.1029/2005JD006387.
Andreadis K. M., D. P. Lettenmaier (2006), Trends in 20th century drought over the continental United
States, Geophys. Res. Lett., 33, L10403, doi:10.1029/2006GL025711.
J. Schaake, J. Demargne, R. Hartman, M. Mullusky, E. Welles, L. Wu, H. Herr, X. Fan, and D. J. Seo
Precipitation and temperature ensemble forecasts from single-value forecasts Hydrol. Earth Syst.
Sci. Discuss., 4, 655-717, 2007
J. Schaake, K. Franz, A. Bradley, and R. Buizza The Hydrologic Ensemble Prediction EXperiment
(HEPEX) Hydrol. Earth Syst. Sci. Discuss., 3, 3321-3332, 2006
D.-J. Seo, H. D. Herr, and J. C. Schaake A statistical post-processor for accounting of hydrologic
uncertainty in short-range ensemble streamflow prediction Hydrol. Earth Syst. Sci.
Discuss., 3, 1987-2035, 2006
E. P. Maurer and H. G. Hidalgo Utility of daily vs. monthly large-scale climate data: an
intercomparison of two statistical downscaling methods Hydrol. Earth Syst. Sci. Discuss., 4, 34133440, 2007
N. Christensen and D. P. Lettenmaier A multimodel ensemble approach to assessment of climate
change impacts on the hydrology and water resources of the Colorado River basin Hydrol. Earth
Syst. Sci. Discuss., 3, 3727-3770, 2006
E. McBean and H. Motiee Assessment of impacts of climate change on water resources – a case study
of the Great Lakes of North America Hydrol. Earth Syst. Sci. Discuss., 3, 3183-3209, 2006
L. M. Bouwer, J. C. J. H. Aerts, P. Droogers, and A. J. Dolman, Detecting the long-term impacts from
climate variability and increasing water consumption on runoff in the Krishna river basin (India)
Hydrol. Earth Syst. Sci. Discuss., 3, 1249-1280, 2006
Ajami N. K., Q. Duan, S. Sorooshian (2007), An integrated hydrologic Bayesian multimodel
combination framework: Confronting input, parameter, and model structural uncertainty in
hydrologic prediction, Water Resour. Res., 43, W01403, doi:10.1029/2005WR004745
Moradkhani H., K. Hsu, Y. Hong, S. Sorooshian (2006), Investigating the impact of remotely sensed
precipitation and hydrologic model uncertainties on the ensemble streamflow forecasting,
Geophys. Res. Lett., 33, L12401, doi:10.1029/2006GL026855.
Hong Y., K.-L. Hsu, H. Moradkhani, S. Sorooshian (2006), Uncertainty quantification of satellite
precipitation estimation and Monte Carlo assessment of the error propagation into hydrologic
response, Water Resour. Res., 42, W08421, doi:10.1029/2005WR004398
Hogue T. S., L. A. Bastidas, H. V. Gupta, S. Sorooshian (2006), Evaluating model performance and
parameter behavior for varying levels of land surface model complexity, Water Resour. Res., 42,
W08430, doi:10.1029/2005WR004440
Bastidas L. A., T. S. Hogue, S. Sorooshian, H. V. Gupta, W. J. Shuttleworth (2006), Parameter
sensitivity analysis for different complexity land surface models using multicriteria methods, J.
Geophys. Res., 111, D20101, doi:10.1029/2005JD006377
Liu Y., H. V. Gupta (2007), Uncertainty in hydrologic modeling: Toward an integrated data
assimilation framework, Water Resour. Res., 43, W07401, doi:10.1029/2006WR005756
Hogue T. S., L. A. Bastidas, H. V. Gupta, S. Sorooshian (2006), Evaluating model performance and
parameter behavior for varying levels of land surface model complexity, Water Resour. Res., 42,
W08430, doi:10.1029/2005WR004440
Bastidas L. A., T. S. Hogue, S. Sorooshian, H. V. Gupta, W. J. Shuttleworth (2006), Parameter
sensitivity analysis for different complexity land surface models using multicriteria methods, J.
Geophys. Res., 111, D20101, doi:10.1029/2005JD006377.
T. Diomede, F. Nerozzi, T. Paccagnella, and E. Todini The use of meteorological analogues to account
for LAM QPF uncertainty Hydrol. Earth Syst. Sci. Discuss., 3, 3061-3097, 2006
D.-J. Seo, H. D. Herr, and J. C. Schaake A statistical post-processor for accounting of hydrologic
uncertainty in short-range ensemble streamflow prediction
Hydrol. Earth Syst. Sci.
Discuss., 3, 1987-2035, 2006
Kang, Hongwen, Kyong-Hee An, Chung-Kyu Park, Ana Liza S. Solis, Kornrawee Stitthichivapak,
Multimodel output statistical downscaling prediction of precipitation in the Philippines and
Thailand Geophys. Res. Letts., 34, L15710, doi:10.1029/2007GL030730, 2007
Marco Marani, Stefano Zanetti, Downscaling rainfall temporal variability, Wat. Resourc. Res. 43,
W09415, doi:10.1029/2006WR005505, 2007
Nunes, Ana MB, John O. Roads Dynamical influences of precipitation assimilation on regional
downscaling, Geophys. Res. Letts. 34, L16817, doi:10.1029/2007GL030247, 2007
J. Schmidli. C. M. Goodess, C. Frei, M. R. Haylock, Y. Hundecha, J. Ribalaygua, T. Schmith,
Statistical and dynamical downscaling of precipitation: An evaluation and comparison of
scenarios for the European Alps, J Geophys. Res.112, D04105, doi:10.1029/2005JD007026,
2007
Vrac, M, M. L. Stein, K. Hayhoe, X.-Z. Liang A general method for validating statistical
downscaling methods under future climate change, Gephys. Res. Letts. 34, L18701,
doi:10.1029/2007GL030295, 2007
N. Christensen and D. P. Lettenmaier A multimodel ensemble approach to assessment of climate
change impacts on the hydrology and water resources of the Colorado River basin Hydrol. Earth
Syst. Sci. Discuss., 3, 3727-3770, 2006
A. Pietroniro, V. Fortin, N. Kouwen, C. Neal, R. Turcotte, B. Davison, D. Verseghy, E. D. Soulis,
R. Caldwell, N. Evora, and P. Pellerin Using the MESH modelling system for hydrological
ensemble forecasting of the Laurentian Great Lakes at the regional scale, Hydrol. Earth Syst. Sci.
Discuss., 3, 2473-2521, 2006
E. Roulin Skill and relative economic value of medium-range hydrological ensemble predictions,
Hydrol. Earth Syst. Sci. Discuss., 3, 1369-1406, 2006
T. Hashino, A. A. Bradley, and S. S. Schwartz, Evaluation of bias-correction methods for ensemble
streamflow volume forecasts, Hydrol. Earth Syst. Sci. Discuss., 3, 561-594, 2006
Recent HAP activities (meetings and workshop)

HAP working group scientists participated in a workshop organized by the
HEPEX in June 2007 (3rd HEPEX Workshop, June 27-29, 2007, Stresa, Italy).
The workshop focused on methodological issues related to seasonal hydrological
forecasts as well as testbed activities where the science was being evaluated.

The HAP strategic plan has an element related to join scientific activities between
GEWEX and IAHS, which included a joint working group. These activities
include applying GEWEX science and data sets to the international Prediction of
Ungauged Basins (PUB) and hydrologic model calibration under MOPEX. At the
recent IUGG meeting (July 2007), the scope of activities under the working
group, and its structure, was updated.
A new Working Group on
Hydrometeorologic Projects was formed to replace the former IAHS/WMO
Working Group on GEWEX that was founded in 1988

HAP helped to organize a highly successful IAHS Symposium ‘’ for the recent
IUGG meeting (July 2007).
3. Planned activities for next year

Finalizing the HAP working groups. Progress has been made in forming the first
group, the seasonal forecasting working group, which at present is incomplete. As
a sub-group (or separate working group), will focus on specific testbeds where the
seasonal hydrologic forecasts will be evaluated for usefulness in water resources
decision making. Comments regarding populating this part, which relates to
needed increased participation from the RHP, is provided below. A third working
group is needed to develop the IAHS and PUB elements of HAP. Partial
membership has been identified. The of the IAHS/WMO Working Group on
GEWEX by the Working Group on Hydrometeorologic Projects at the 2007
IUGG meeting in Perugia will help us identify additional working group member.
A final working group, that may be drawn from the above working group, is a
joint GEWEX/HAP – GWSP working group. The charge to this group would be
to identify testbeds and joint science activities that advance the goals of both
activities.

The CEOP coordinators from the Regional Hydrometeorological Projects (RHP),
previously the Continental Scale Experiments, have a responsibility to identify
RHP investigators interested in establishing HAP/HEPEX testbed sites. It is these
local researchers who can best evaluate the usefulness of the seasonal forecasts
and work with local water resources decision makers. It is the goal of HAP to
have one testbed in each RHP. HAP requests that over the next six months the
RHP coordinators identify one testbed and testbed scientist for their RHP. Links
between existing HEPEX test-bed projects and some of the RHPs need to be
strengthened.

Developing a draft science/implementation roadmap, including a project timeline.
The science plan for the seasonal hydrological forecasting is further advanced
than the IAHS/PUB/HAP activities. Nonetheless, three themes are emerging:
improvements in hydrological modeling, including parameterizations and
calibration that relate to the MOPEX experiment; predictions in ungauged basins
using GEWEX data sets and procedures, including remote sensing data sets; and
analyzing hydrologic sensitivity to climate change, including identifying regions
and basins that are deemed particularly vulnerable to climate change from a
hydrologic and water resources perspective. Finally as mentioned above,
science/implementation roadmap needs to be developed for joint activities
between GEWEX/HAP and GWSP. The activities will range from assessing
seasonal forecasts for water management to assessing hydrologic sensitivity to
climate change for major basins/regions of the globe.

Testing procedures for re-scaling and down-scaling atmospheric forecasts for
hydrologic application in several HAP/HEPEX test-bed projects will be further
developed. It was proposed at the HEPEX workshop in Stressa, Italy (June 2007)
that a joint GEWEX/HAP, HAPEX EU/ENSEMBLE downscaling workshop be
held. The EU ENSEMBLE project is developing a downscaling portal.

Testing a prototype operational procedure for the U.S. NOAA/National Weather
Service for correcting bias and spread problems in existing seasonal hydrologic
ensemble forecasts.

Completing a global set of seasonal hydrologic hindcasts. Initially these will be
carried out for the HAP/HEPEX testbeds and selected other regions.

Helping to conduct a HEPEX workshop on hydrologic uncertainty and postprocessing to be held at Delft University in June 2008.

Continuing to plan future HAP/HEPEX workshops and test-bed projects.

Continue to strengthen hydrologic aspects of CEOP Reference Sites.

Continue to participate in GEO Water Projects and to foster links between the
Asian Water Cycle Initiative (GEO project WA-08-P1) and HEPEX (GEO project
WA-06-02)
4. Issues and Recommendations
The biggest challenge facing HAP over the next year is still the establishment of the HAP
working group and making progress on the science/implementation plan. HAP needs to
identify task leaders to help implement the specific activities (goals) of the project. This
is an area where the CEOP Regional Hydrometorology Projects (RHP) can help, and
HAP asks for the support of the GEWEX SSG in seeing if this can happen. It is
recommended that GEWEX SSG better define GEWEX’s participation in the WCRP
Task Force on Seasonal Prediction as it relates to seasonal hydrologic prediction, and
possibly a HAP representative to participate on the TFSP.
5. Contribution to GEWEX
HAP is the CEOP activity that has as its goals determining the extent to which current
hydrologic conditions can be accurately assessed and determining whether reliable,
skillful hydrologic ensemble forecast procedures based on seasonal climate model
forecasts can be developed and made useful for water resources. The project will
demonstrate the above through demonstration projects and test-bed sites.
Contributions to WCRP strategic framework:
HAP will contribute to the strategic themes of WCRP, particularly as they relate to the
activities of the Task Force on Seasonal Prediction (TFSP). The overarching goal of
TFSP is “to determine the extent to which seasonal prediction is possible and useful in all
regions of the globe with currently available models and data”, which is synergistic with
HAP, with the latter having seasonal hydrologic prediction at scales useful for water
management as its focus.
Contributions to society and to WCRP/GEWEX visibility:
The potential contributions of HAP in developing demonstration projects and data sets
related to assessing current hydrologic conditions (nowcasting) and hydrologic
forecasting to international efforts like GEOSS are significant and are being pursued.
Understanding regions where hydrologic seasonal predictions have skill, and
demonstrating this skill is critical for society.
6. List of members (suggested)
The current Chair is Eric Wood (Princeton University) whose term began in the Spring
2006. At this time there is no formal ‘organizational structure’ for HAP, but suggested
working group participants are listed below.
Potential Working Group members (group leaders designated by *)
1. Focus Area 1: Seasonal Hydrological forecasting
Dennis Lettenmaier* (U Washington, USA)
Manu Lall (Columbia/IRI, USA)
Andy Wood (U Washington, USA) (US test-bed)
Lifeng Luo (Princeton University, USA) (US test-bed)
Martyn Clarke (NIWA, New Zealand)
John Schaake (consultant, USA)
A. Gaye (University of Dakar, Senegal) (AMMA test-bed, also on RHP)
Taikan Oki (University of Tokyo, Japan)
Martin Best (UK Met Office, UK) (also on GMPP)
Yuping Yan (Chinese Met Service, China)
2. Focus Area 2: Hydrological modeling, including activities related to PUB,
MOPEX, data assimilation of remote sensing)
Guenter Bloeschl, Technical University, Vienna Austria
M. Sivapalan, U Illinios, USA)
K. Takeushi, Yamanashi Univeristy, Japan
Vasken Andreassen (CEMAGREF, France/IAHS)
Terri Hogue (UCLA, USA/IAHS)
Ian Littlewood (CEH, UK/IAHS)
Barry Croke (Australia/IAHS)
Alan Hall (consultant, Australia)
Yann Kerr (CNES, Toulouse, France)
Kuni Takeuchi (Yamanashi University, USA)
John Schaake (consultant, USA)
Paul Houser (George Mason Univeristy, USA)
Dennis Lettenmaier, U Washington, USA)
Eric F Wood (Princeton University, USA)
Wolfgang Grabs (WMO, Geneva)
Christa Peters-Lidard (NASA/GSFC, USA)
…