April 2010 Office of Hydrologic Development Hydrology Laboratory Strategic Science Plan OHD-HL Strategic Science Plan Executive Summary Executive Summary This Strategic Science Plan (Plan) establishes the directions for research in hy- drology at the Hydrology Laboratory of the Office of Hydrologic Development. It first establishes a cross-reference between the Plan and NOAA, NWS, OHD policy documents, and to the National Research Council reviews of relevant NWS programs, especially those recommending the development of a strategic science plan for hydrologic research at the NWS. Furthermore, the Bulletin of the American Meteorological Society (BAMS) article by Welles et al. (2007) high- lights the need for hydrologic forecast verification, and how this verification should be a driving force for new model development. A main section of the document is dedicated to the verification topic. This document is intended to be a “living document” to be updated on an annual basis. The Plan follows closely the outline of the Integrated Water Science Team re- port. In each section the Plan offers several subsections: where we are, in which it details what the state of the science at OHD is; where we want to be, where the Plan sets the new directions or reaffirms existing directions; what are the chal- lenges to get there, and a road map to reach those goals. The highlights of the Plan are: The Plan directs the research on hydrologic modeling seeking: • A more expeditious and cost-effective approach by reducing the effort re- quired in model calibration while keeping reliability in model forecasts. • Improvements in forecast lead-time and accuracy. • Provide for the rapid adjustment of model parameters to account for changes in the watershed, both rapid as the result from forest fires or levee breaches, and slow, as the result of watershed reforestation. • Hydraulic modeling. • A comprehensive ensemble approach to hydrologic forecasting. • Data assimilation for lumped and distributed models. • In future versions of this plan: o The impact of climate variability change on hydrologic forecasting. o Water quality modeling. o Social Science research. To this end, it places an emphasis on research of models with parameters that can be derived from physical watershed characteristics. Purely physically based mod- els may be unattainable or unpractical, and, therefore, models resulting from a combination of physically and conceptually approached processes may be re- quired. The plan acknowledges that the path in that direction is not clearly de- fined yet, as evidenced by the DMIP-1 and DMIP-2 results, and that OHD is pro- ceeding in that direction, first, with the development of the a priori parameter es- OHD-HL Strategic Science Plan i Executive Summary timates for the Sacramento model, and second, with the development of the Heat- Transfer modification to the Sacramento model. For snow science, the research will be directed towards energy-budget models. This section will be addressed by a separate Snow Science Plan to be developed by the Snow Science Steering Team, once the present plan is approved. The Hydrometeorological forcings section emphasizes the development of im- proved precipitation estimation techniques through the synthesis of radar, rain gauge, satellite, and numerical weather prediction model output, particularly in those areas where ground-based sensors are inadequate to detect spatial variabil- ity in precipitation. Better estimation and forecasting of precipitation are most likely to be achieved by statistical merging of remote-sensor observations and forecasts from high-resolution numerical prediction models. Enhancements to the satellite-based precipitation products will include use of TRMM precipitation data in preparation for information to be supplied by the Global Precipitation Mission satellites not yet deployed. Because of a growing need for services in water resources, including low-flow forecasts for water supply customers, the plan directs research into coupled sur- face-groundwater models that will eventually replace the groundwater compo- nent of the existing models, and will be part of the new generation of models. The Plan confirms the directions set forth in the respective planning documents of both the ensemble research and the verification system. In NWS operations, forecasters modify model state variables, forcings or even parameters to adjust model output to match observed streamflow. These adjustments, known as “modifications” or simply “mods,” are essentially a manual form of data assimi- lation. Moving into the realm of operational use of ensemble forecasting with distributed hydrologic models, “mods” become impractical, given the impossibil- ity to what subcomponents (cells) of a watershed distributed model to adjust. Furthermore, doing “wholesale” (i.e. “lumped”) adjustments to cell contents or forcings defeats some of the advantages of distributed modeling. Therefore, it is imperative either to adapt existing or to develop new techniques to support auto- matic error correction in distributed models. Chapter 7 describes ensemble mod- eling. Chapter 8 covers data assimilation, and Chapter 9 delineates the verifica- tion plan. Two key components of the implementation of this strategic plan are the Com- munity Hydrologic Prediction System (CHPS), currently under development in collaboration with Deltares (http://www.deltares.nl/xmlpages/page/deltares_en), and the Hydrology testbed. The testbed will serve as an environment for the de- velopment of advanced science and software engineering techniques, moving the hydrologic forecasting applications developed since the 1970s for mainframe ii OHD-HL Strategic Science Plan computers, into distributed processing systems as the computational demands so require. This first version of the plan does not cover the following topics: hydraulic mod- els; water quality models; effects of climate change and variability on hydrologic forecasting; irrigation, and social sciences. These will be in the next year’s up- date. Reference Welles E., S. Sorooshian, G. Carter, and B. Olsen. (2007). “Hydrologic Verifica- tion: A Call for Action and Collaboration.” BAMS, 88(4), April, 503-511. OHD-HL Strategic Science Plan iii Acknowledgements Acknowledgements This report is a collaborative effort of the Strategic Science Plan Team, which consisted of: Gary Carter, Team Mentor Pedro Restrepo, Team Leader John Kochendorfer, Coordinating Lead Author, and Appendices A and B main author Mike Smith, Seann Reed, Victor Koren, and Brian Cosgrove Chapter 3 Con- tributing Authors Dave Kitzmiller, David Riley, Denis Miller Chapter 4 Contributing Authors D.J. Seo, Chapters 6 and 7 Contributing Author Julie Demargne, Chapters 8 Contributing Author Additional contributions and suggestions were also made by Geoff Bonnin, Ken Mitchell, John Schaake, Jay Day, Tim Love, Billy Olsen, Kevin Werner, Don Laurine, Mike Ek, Tim Schneider, and scientists from NSSL. Chapters 6 and 7 incorporate input from the DSST conference calls in 2008 on R&D and RTO planning of XEFS Phase 2, in which all RFCs participated. OHD-HL Strategic Science Plan v Contents Contents Executive Summary i Reference iii Acknowledgements v Contents vii Figures xii Abbreviations and Acronyms xiii 1. Introduction 1 1.1 The Role of OHD within the NOAA Mission Goals 1 1.1.1 NOAA Mission 1 1.2 OHD Strategic Science Goals 2 1.3 Organization of the Plan 3 1.4 References 6 2. A High-Level View 7 2.1 The Current Hydrologic Forecasting Process 7 2.2 The Future Hydrologic Forecasting Process 9 2.3 References 13 3. Hydrologic Models 16 3.1 Surface Properties 16 3.1.1 Where We Are 16 3.1.2 What Our Partners Are Doing 17 3.1.3 Where We Want to Be 17 3.1.4 Challenges to Getting There 17 3.1.5 A Road Map for Getting There 17 3.2 Infiltration and Surface Runoff 18 3.2.1 Where We Are 18 3.2.2 What Our Partners Are Doing 19 3.2.3 Where We Want to Be 19 3.2.4 Challenges to getting to where we want to be 20 3.2.5 A Road Map for Getting There 21 3.3 Soil Moisture and Temperature 21 3.3.1 Where We Are 21 3.3.2 What Our Partners Are Doing 23 3.3.3 Where We Want to Be 25 3.3.4 Challenges to Getting There 26 3.3.5 A Road Map for Getting There 26 3.4 Groundwater Storage and Base Flow 27 3.4.1 Where We Are 27 3.4.2 What Our Partners Are Doing 27 OHD-HL Strategic Science Plan vii Contents 3.4.3 Where We Want to Be 27 3.4.4 Challenges to Getting There 28 3.4.5 A Road Map for Getting There 28 3.5 Snow Accumulation, Sublimation and Melt 28 3.5.1 Where We Are 29 3.5.2 What Our Partners Are Doing 29 3.5.3 Where We Want to Be 30 3.5.4 Challenges to Getting There 31 3.5.5 A Road Map for Getting There 31 3.6 Evapotranspiration 32 3.6.1 Where We Are 32 3.6.2 What Our Partners Are Doing 33 3.6.3 Where We Want to Be 34 3.6.4 Challenges to getting there 34 3.6.5 A Road Map for Getting There 34 3.7 References 35 4. Hydraulic Modeling, Hydrologic Routing and Flood Mapping 43 4.1 Inland River Modeling 43 4.1.1 Where We Are 43 4.1.2 What Our Partners are Doing 44 4.1.3 Where We Want to Be 44 4.1.4 Challenges to Getting There 45 4.1.5 A Road Map For Getting There 46 4.2 Dam and Levee Break Modeling 46 4.2.1 Where We Are 46 4.2.2 What Our Partners are Doing 47 4.2.3 Where We Want to Be 47 4.2.4 Challenges to Getting There 48 4.2.5 A Road Map For Getting There 48 4.3 River-Estuary-Ocean Modeling 49 4.3.1 Where We Are 49 4.3.2 What Our Partners are Doing 49 4.3.3 Where We Want to Be 50 4.3.4 Challenges to Getting There 50 4.3.5 A Road Map For Getting There 51 4.4 Flood Forecast Mapping 51 4.4.1 Where We Are 51 4.4.2 What Our Partners are Doing 51 4.4.3 Where We Want to Be 52 4.4.4 Challenges to Getting There 52 4.4.5 A Road Map for Getting There 53 4.5 Water Quality (Future) 53 4.6 References 53 viii OHD-HL Strategic Science Plan Contents 5.