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Hydrology of Inland Flooding. Stream Gauges Hydrologic Forecast Process Forecast Considerations Forecast Hydrographs. 3-1. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. Stream Gauges. - PowerPoint PPT Presentation
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Hydrology of Inland Flooding
Stream Gauges Hydrologic Forecast Process Forecast Considerations Forecast Hydrographs
3-1
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Stream Gauges
Manual gages (wire weight or staff)• Low cost• By definition, requires trained human
observer• Not usually available at night
Automated gages• Installation costs + Maintenance costs• Available 24/7
Hydrologic Forecast Process
Modeling how much rain gets into the river (Rainfall to Runoff)
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)
Rainfall to Runoff Modeling
Rainfall to Runoff Modeling
Rain
T=0 hours
DIRECT
SURFACE
INTERFLOW
BASEFLOW
6 hours
12 hours
24 hours
18 hours
30 hours
Unit Hydrograph
6 12 18 24 30 36 42 48 54 600
2000
4000
6000
8000
10000
12000 North River at Palmyra, Missouri
Flow (cfs)
Time (Hours)
Routing
Time
Gage
Heig
ht
Meramec River near Steelville, MO
Hickory Creek near Bluff City, IL
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
Forecast Hydrographs
Model Hydrographs Forecast Hydrographs
Model Hydrograph
Summary
Which river gauge requires a stilling well?
A. Acoustic sonarB. Float typeC. Pressure transducer
Summary
What type of runoff causes the river to rise the quickest?
A. Direct runoffB. InterflowC. Baseflow
Summary
What hydrologic method takes basin-wide runoff and converts it to flow (discharge) over a period of time at the river gauge?
A. Rainfall to Runoff modelB. Unit HydrographC. Routing modelD. Rating curve
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