Download - Hydrology in the National Weather Service
Hydrology in the National Weather Service
Mark FuchsService Hydrologist
National Weather ServiceSt. Louis, MO
Presentation to local Media PartnersNovember 16, 2013
• Define flooding and hydrology• Describe factors that contribute to flooding and define flooding categories• Describe the CHPS and the hydrologic forecast process at the RFCs• Provide an overview of the Advanced Hydrological Prediction Service (AHPS) resources and 90-day streamflow outlook tools• Provide additional NWS resource locations
Objectives
Growing Demand for Water Information
• Flash Flood – a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (e.g., intense rainfall, dam failure, ice jam).
• Flood – high flow, overflow, or inundation by water which causes or threatens damage.
Flood vs. Flash Flood
• Pre-season water levels• Received precipitation/snowfall• Air/ground temperature• Soil moisture• Ice Jams• Snowpack/snow melt
Factors Contributing to a Flood
• Action Stage: Water is near or over the top of its banks in spots, but no structures are flooded; any flooding is typically limited to parkland and marshland.
• Minor Flood Stage: Few buildings are expected to be inundated, roads, parklands and yards may be covered with water and water may go under buildings on stilts or higher elevations.
• Moderate Flood Stage: Inundation of buildings, roads closed and/or cut off. Some evacuations may be necessary.
• Major Flood Stage: Significant to catastrophic, life-threatening flooding is expected. Extensive flooding with some low-lying areas completely inundated. Structures may be completely submerged. Large-scale evacuations may be necessary.
Flood Categories
NWS USACE USGS
• NWS – Forecasts• USACE – Engineering and Reservoirs• USGS – River observations and measurements
USGS and USACE river gauges
USACE water control
NWS OperationsAverage Person Only Sees Tip of Iceberg
Private Weather Companies
InternetRadioTV
NWR
122 Weather Forecast Offices
9 National Centers for
Environmental Prediction
13 RiverForecastCenters
Radar Network
SatellitesWeather Balloons
Ground-LevelObservations
Data Buoys
Climate andSeasonalOutlooks
VolunteerNetwork
ModelSimulations
Aviation & Ocean Forecasts
Severe Thunderstormand Tornado Prediction
Space WeatherForecasts
HurricaneForecasts
Government
StreamGauge
Network
River Forecasts
90-day outlooks
11
NWS OperationsPresence at National, Regional and Local Levels
NWS River Forecasts
NWS River Forecast Centers
www.water.weather.gov/ahps/rfc/rfc.php
Three River Forecast Centers serve the St. Louis Service Area
14
MBRFC
NCRFC
LMRFC
FCFEWS
National Weather Service Northeast River Forecast Center 15
CHPS: Community Hydrologic Prediction System
FEWS Models
NWS Models
HEC Models
Other Models
CHPS
CHPS NERFC – Alternative data views
CHPS: Providing the forecaster an interface to data
• Intuitive graphical interfaces• Lots of map support• Highly configurable views
CHPS NCRFC – flood status in several catchments
CHPS: Data visualization and editing – Graphical data
• Powerful graphical tools for viewing time series data
• Point time series Longitudinal profiles (animated)
• Editing capabilities – copy to-from e.g. Excel
Historical event: River Rouge, Detroit
Longitudinal Display
CHPS: Using and displaying probabilistic data
• Import ensemble data (e.g. ECMWF, GFS, NAM)• Run models for ensemble members• Results
– Statistical Summary– Verification
The CHPS database model is inherently ensemble-aware
Model #2 for 31-05-2007 00:00 UTC
Model #1 for 31-05-2007 00:00 UTC
Hydrologic Forecast Process
Modeling how much rain gets into the river (Rainfall to Runoff)
Modeling snowmelt runoff (Snow model) Modeling how fast water gets to the river
gage (Unit Hydrograph) Modeling how fast upstream water arrives
at the gage (Routing) Translating water volume into water height
(Rating)
Soil Moisture Conditions
Accumulated snow and ice pack
Observed Precipitation
Forecast Precipitation
Rainfall to Runoff Modeling
6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120 126 132 138 144 150 156
0
2000
4000
6000
8000
10000
12000
14000
Series1
Time (hours)
Unit HydrographMeramec River near Steelville, Missouri
Flow
(cfs
)
Routing
Time
Gage
Heig
ht
River Forecasts – How are they created?
Observed Precipitation
Future Precipitation
Soil ModelRainfall to Runoff
Local Basin
Rating CurveFlow to Stage
Unit HydrographRunoff to Flow
Upstream FlowUpstream River Gage
Basin Local Flow Total Flow(cfs)
ForecasterModification
ForecastTo Public
Forecast River Gage
Forecast Considerations
Ground State (How dry is it?) Past Model Performances Rainfall (Gage-based or Radar-based?) Rainfall Variability
• Space• Time
Rainfall Variability
Rainfall Variability
Rainfall Variability
Rainfall Variability
Rainfall Variability
RFC Products and Services
WFO Products and Services
• These graphical products are useful planning tools.
• Enable users to make more informed decision about policies and actions to mitigate the dangers posed by floods and droughts.
• New feature demo
AHPS
River Forecasts
ImpactsWhat constitutes impacts?– Flooded cropland and parks– Flooded roadways– Damaged storage buildings and garages– Businesses and residences– Levee breaches vs. overtopping– Navigational issues– Water intake problems
Defined as any water level disrupting human activity.
Impacts
Low Flow and Impacts
Experimental Long-Range River Flood Risk
Probability Outlooks
Probability Outlooks
Spring Outlooks
December 2013 – February 2014
December 2013 – February 2014
Resources
• www.water.weather.gov• www.weather.gov• www.cpc.ncep.noaa.gov• www.wpc.ncep.noaa.gov• www.nohrsc.nws.gov
Questions