Hydrology You Can Use

The National Water Model and the NWS West Gulf River Forecast CenterGregory WallerService Coordination HydrologistNWS West Gulf River Forecast Center

NWS MissionTo provide weather, water, and climate data, forecasts and warnings for the protection of life and property and enhancement of the national economy.

NWS accomplishes this mission in close collaboration and cooperation with State, Local, and Other Federal Agencies

2The NWS needs its partners to do its job.

The WGRFC AreaDiverse Water Issues

402,000 mi2 total area 87,000 mi2 in MX (Rio Grande headwaters)320 forecast points, 15 major river systemsOver 65,336 miles of rivers (U.S. only)Snowpack Water supplyHill Country HydrologyFlash flood threatsRapid river responsesCycles of Flood/DroughtTropical cyclonesStorm surge Coastal floodingProlonged river floodingInternational Border Water AllocationComplex reservoir operations

All sorts of hydrology. Varied skill set of staff to deal with the variable meteorology/hydrology across the region.3

NowThe Hydrologic Cycle

Courtesy of the USGS Water Science School

Water evaporates, moves from the sea to land, condenses into clouds eventually, precipitation forms, and either soaks into ground (ground water) or surface runoff back to the sea.4

The MeteorologyPast rainfallHourly4km grid Future rainfall6 hourlyBlend of model and humanAt West Gulf RFC, we routinely use 12 hours of future rainfall in our hydrologic forecasts (can extend on rare occasions)

WGRFC forecasters provided precip input to enhance the hydrologic model forecast. We forecast on a forecast5

Precipitation Best Estimate 4km x 4km spatial resolution1 hour temporal resolutionHuman quality control of data inputs

Gauge

Radar

Satellite

Best Estimate (Multi-sensor Field)Satellite

An example, where filling in and combining fields helps in radar poor areas.6

Precipitation Forecast/QPF4 km x 4 km spatial resolution6 hour temporal resolution72 hours (12 periods) processed RFCs ingest 6-24 hours (1-4 periods) operationally in hydrologic modelsAdditional periods ingested based on confidence in forecast

Guidance forecast issued by National CenterForecaster at RFC makes adjustments based on local expertise

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The Hydro ModelCommunity Hydrologic Prediction SystemHydrologic ModelThink more math, less physicsHas capability of plugging in other models

Hydrologic model does not take into account physics. It is a conceptual model, requiring constatn human calibration as the soil use changes.8

Hydrologic Forecast ProcessA lot of estimatesEstimate how much rain gets into the riverRainfall to RunoffEstimate timing (how fast) of runoff to the river gage Unit HydrographEstimate how fast any upstream water arrives at the gage RoutingEstimate water flow (we use) into water height (the public uses)RatingWe can modify any/all of the above

5 estimates go into a forecast, a 5 day forecast to a 0.10 ft accuracy. 9

Soil Accounting Model Output

5cm10cm20cm50cm100cmFractional Water Content at Depth

RDHM SacHT Output

Think of the soil as buckets. Once a bucket is fullrunoff. There are holes in the buckets to drain at variable speeds.10

The Result Our Model

Screen captures of CHPS showing routing, rainfall and runoff, and timing issues.11

Precipitation estimates and forecasts merged into continuous datasetPrecipitation dataset ingested into hydrologic model. Forecasters adjust model parameters in real timeRiver forecast issued to public

Rainfall AnalysisHydrologic ModelingForecastWest Gulf River Forecast Center

Past precip updated every hour, future precip updated every 6 hours, SAC SMA calculations run, forecasters makes edits, sends forecast to the web.12

Operational EvolutionThe National Water CenterUniversity of AlabamaBring federal water partners together

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The Change in Texas102,000 NHDPlus reach catchments for TexasAverage area 7.1 km2Average reach length 3 km The FutureNHDPlus reach catchmentUniquely labeled across nation

15 Forecast Groups320 Forecast LocationsAlmost 600 Modeled Watersheds

Now

Timelines and StuffShort Term Uses HRRR (High Resolution Rapid Refresh) QPFOut 15 hours (soon to be 18 hours in April)Ran hourlyMedium TermUses GEFS (Global Ensemble Forecast System) QPFOut 10 daysRan once per day (soon to be run 4 times daily in April)Long TermUses bias corrected CFS (Climate Forecast System) QPFOut 30 daysRan once per day

The medium term run, which has critical information in a critical time frame (beyond 15 hours but within 48 hours), only runs daily. This is not optimum for WG hydrology/operations.16

Meteorology Inputs

WRF-Hydro Forecasting Model

Runoff

Streamflow RAPID flow routing (for continental US)Probabilistic flood forecasts

Weather model and forecasts (HRRR)Land-Atmosphere Model (NOAH-MP)Precipitation Weather

Catchment-level forecasts

Parallel Ops Met input is the HRRRgoes to NOAH-MP, not SAC-SMA model for runoff. Multiple runs (ensemble approach for inputs) will eventually provide ensemble hydrographs (not now, in the future)18

National Water Model

Go to the web pageget the wordy disclaimer19

The NWM

Drill Down

Pick a site. Only flow right now Short Range is based on the HRRR, Medium Range has the GEFS, with Long Range using the biased CFS21

Anomalies

Good information. Look here leading into the eventthen zone in on the RFC forecasts as we get closer to the event22

Output from the NWMOutput from model is herehttp://nomads.ncep.noaa.gov/pub/data/nccf/com/nwm orftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/nwmGeospatial data is hereftp://ftp.nohrsc.noaa.gov/pub/staff/keicher/WRFH_ppd/web/NWM_nc_tools.tar.gz

How We Stay S.A.

Another Tool in the ToolboxWill be able to provide streamflow information at intermediate pointsHigher resolution gridsExpansion of flood inundation mapsRequires verification and validation ongoing at RFCsOperational August 2016http://water.noaa.gov/mapIMO, expect full capability with 5 to 10 years

Even though it is operational, it is still a work in progress.25

Questions/Comments?

Gregory WallerService Coordination HydrologistNWS West Gulf River Forecast Centergreg.waller@noaa.gov