1. Hydrologic Modeling Strategy
National Water Center
Hydrologic Modeling Strategy
Presented By: Brian Cosgrove (NWS/NWC)
Contributors: David Gochis (NCAR/RAL), Michael Ek (NWS/NCEP)

2. Operational System Attribute(s)
System Name
Acronym
Areal Coverage
Horz Res
Cycle Freq
Fcst Length (hr)
WRF-Hydro Data Assimilation System
WRF-Hydro Analysis
CONUS+
1km / 250m / 2.7 million catchments & reaches
1-Hr
6-Hr Analysis
WRF-Hydro Short Range Forecast System
WRF-Hydro
3-Hr
2 days
WRF-Hydro Medium Range Forecast System
1km / 250m / 2.7 million catchments & reaches
24-Hr
10 days
WRF-Hydro Long Range Forecast System
1km / 2.7 million catchments & reaches
48-Hr
30 days
System Data Assimilation or Initialization Technique
System
Attributes
WRF-Hydro Analysis
Initialized with states from previous WRF-Hydro analysis cycle. Streamflow observations assimilated with nudging-based method.
WRF-Hydro
Initialized with states taken from most recent WRF-Hydro analysis cycle.

3. Why System(s) are Operational
Primary stakeholders and requirement drivers
Flash flood forecasts (NWS service assess., FEMA, stakeholder summits)
Street-level flood forecasts (NWS service assess., FEMA, emerg. mgrs)
Operational extended water resource forecasts (Army Corps, RBC)
Fully coupled river-to-estuary modeling (NOAA strat. goals, serv. assess.)
What products are the models contributing to?
Guidance from WRF-Hydro will support NWS flood and flash flood forecasts, FEMA emergency responses, Army Corps reservoir management, interagency drought monitoring, ecological forecasting and National Ocean Service modeling
What product aspects are you trying to improve with your development plans?
We are improving flood forecast products in a transformational way, supporting street-level impact-based predictions of hazards
Water supply and drought products, along with coastal modeling will be improved
Top 3 System Performance Strengths
1) Street-level resolution of hydrologic processes, 2) Representation of multiple hydrologic routing processes, 3) Modularity and connectivity of system
Top 3 System Performance Challenges
1) Long-term data storage and delivery to end users, 2) Rapid growth of computational requirements, 3) Universal challenge of verification

4. System Evolution Over the Next 5 Years
Major forcing factors
Drive for coupled process modeling (ocean, atmosphere, river, estuary)
Hyper-local information required in increasingly populated and vulnerable areas
Science and development priorities
Expanded data assimilation capabilities
Coupled hydraulic, coastal modeling
Hyper-resolution modeling
Addition of hydrologic processes for higher fidelity simulations
Development of upscaling/downscaling approaches to connect EMC/NWC
What are your top challenges to evolving the system(s) to meet stakeholder requirements?
Computational resources and communications bandwidth
Availability of data for forcing, verification and assimilation
Potential opportunities for simplification going forward
WRF-Hydro integration into NEMS (in progress)
Where possible, integrate model and forcing evaluation system driven by development of NWC Water Resource Evaluation Service (WRES) and efforts at NCEP/EMC
Where possible, leverage a common NCEP/NWC forcing data engine

5. Top 3 Things You Need From the UMAC
Continuation of efforts to integrate total water prediction into fabric of NOAA Earth system modeling and reduce cross-office and cross-agency barriers
Neutral input into vision of cross-office and interagency modeling strategy
Support for links to projects and programs in the broader national and international land surface hydrology community