Transcript Real-Time Flash Flood Forecasting in Small Fast-Responding Watersheds using a Distributed Rainfall-Runoff Model - Michael Schaffner, NWS

Real-Time Flash Flood Forecasting
in Small Fast-Responding
Watersheds using a Distributed
Rainfall-Runoff Model
Michael Schaffner, NOAA National Weather Service,
Binghamton Weather Forecast Office
Carl L. Unkrich, Hydrologic Engineer, USDA ARS Tucson
David C. Goodrich, USDA ARS Tucson
Eastern Region Flash
Flood Conference
June 3, 2010
What are current National Weather Service
(NWS) methods of providing site
specific/basin specific services?
• Flash Flood Monitoring and Prediction Program
(FFMP)
• Site Specific rainfall-runoff models
• Headwater Guidance
• Flash Flood Guidance
FFMP
• This allows the forecaster
to pinpoint (i.e. provide
site specific information)
which basins are receiving
the heaviest rainfall.
• Does not allow the
forecaster in most cases
to determine the timing
and magnitude of an
event.
Available Site Specific Model in
the Middle Atlantic Region
• Antecedent
Precipitation Index
(API)
• One-hour time steps
• Hourly Multi-Sensor
Precipitation Estimator
(MPE) input
• Manual hourly QPF input
KINEROS (kinematic runoff and
erosion model)
•
•
•
•
Distributed model.
Runs on a PC.
Event-based model. Not a continuous model.
Must be started up at about the start time of a heavy
rainfall event.
• Runs using finer time steps than available models.
• Runs using precipitation resolution which is smaller in
terms of spatial and temporal resolution than existing
models.
• Kinematic wave equations.
KINEROS Setup
• Is accomplished by using the Automated
Geospatial Assessment Tool (AGWA).
• AGWA runs using ESRI GIS with Spatial Analyst.
• Uses readily available GIS datasets which can be
obtained free of charge.
• Automated
Geospatial
Watershed
Assessment
(AGWA) Tool
provided by
USDA:
http://www.tucson
.ars.ag.gov/agwa/
Schematic View
Plan View
Composed of a cascade of
overland flow planes and
open channel elements.
Above image from: http://www.tucson.ars.ag.gov/kineros/
Precipitation Input
• The Digital Hybrid Reflectivity Product (DHR).
• DHR provides the highest resolution available in terms of
temporal (every volume scan – 4 to 5 min.) and spatial (1
Km by 1 degree) scale.
• DHR has a Z-R Relationship applied to it and quality control
measures included within the PPS (e.g. for hail) to produce
rainfall for KINEROS.
• KINEROS requires DHR available in real time.
• A new solution is generated every time a new volume scan
of data comes in.
Field Work* / Data Collection
• Required to collect average manning roughness
for each open channel element. Manning
roughness is defined as the average for each
channel element.
• Required to define up- and down-stream channel
widths for each open channel element.
*High resolution aerial imagery can also be used for width measurements,
and in some cases, Manning n.
Starting up the model
• Select initial flow rate
• Select initial soil moisture state (very dry, dry, wet,
or very wet)
• Select date and time of simulation start
• Select Z-R Relationship / QPF (optional)
KINEROS GUI
Platte Kill near Dunraven, NY
• 35 square miles.
• Tributary to the East
Branch of the Delaware
River.
• Collected channel
widths and manning
roughness values at 19
locations.
• Manning roughness
varied from 0.030 to
0.042
Model Calibration Process
• Involves manual calibration using parameter
multipliers.
• Parameter multipliers function on a global basis
maintaining the relative differences across model
elements.
• Saturated hydrologic conductivity multiplier is used
to calibrate the magnitude of the peak flow.
• Channel length multiplier is used to calibrate timing
of the peak flow.
Displaying calibration results…
• Plotting model
parameter multipliers as
a function of maximum
basin average rainfall
intensity.
• A linear regression line
is fit to the data.
• This allows a reasonable
solution to be produced
for a range of rainfall
intensity values.
Typical Hydrographs for Platte Kill
Platte Kill near Dunraven
1800
1600
Discharge (cfs)
•
Reasonable
simulation of peak
flow in terms of
magnitude and
timing.
Rapid rise in rising
limb of hydrograph
from gage data is
likely due to
saturation excess
flow generation and
lateral subsurface
flow into channel
which the model
does not account
for.
1400
1200
1000
Gage
800
Simulation
600
400
200
0
6/26/20 6/26/20 6/26/20 6/26/20 6/26/20 6/26/20 6/26/20
06
06
06
06
06
06
06
07:12
09:36
12:00
14:24
16:48
19:12
21:36
Date and Time
Platte Kill near Dunraven
1200
Discharge (cfs)
•
1000
800
Gage
600
Simulation
400
200
0
3/8/2008 3/8/2008 3/8/2008 3/8/2008 3/8/2008 3/9/2008 3/9/2008 3/9/2008
12:00
14:24
16:48
19:12
21:36
00:00
02:24
04:48
Date and Time
Lead Time: Beaver Kill near Cook Falls, NY
241 square mile fast responding headwater point.
KINEROS can provide lead
time of almost 3 hours on the
flood crest vs. minimal lead
time when compared to the
typical flood warning issued.
Further lead time is possible
when QPF is added.
USGS web cam image:
http://ny.water.usgs.gov/rt/pub/01420500.htm
Ungaged Basins
• Represent an unmet need in
forecasting within the NWS.
• Data can be collected on small
basins using indirect discharge
methods.
• Timing of onset of flooding and
peak flooding can be noted.
Callicoon
Creek, NY
Calibrated originally
for the USGS stream
gage at Callicoon.
May not be
representative of
flooding further
upstream along the
East Branch at
Jeffersonville.
Callicoon Creek at
Jeffersonville Watershed
in KINEROS
Event Date
Description
June 28, 2006
Record flood
July 29, 2009
Minor-Moderate
July 31, 2009
Minor-Moderate
August 2, 2009
¼ Bankfull
August 9, 2009
½ Bankfull
August 22, 2009
½ Bankfull
KINEROS Calibration
Saturated Hydrologic Conductivity
Multiplier
East Branch of Callicoon Creek at
Jeffersonville
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
y = 1.0563x + 0.5401
R² = 0.23
0
0.5
1
1.5
2
2.5
3
3.5
Maximum Basin Average Rainfall Intensity (inches/hour)
Low R2 still allows “categorical” forecasting at Jeffersonville.
4
Summary of Current use of KINEROS
• Used for gaged and ungaged basins.
• Peak flow forecasting for gaged basins including
some headwater river forecast points.
• Peak flow forecasting for ungaged basins under
the limitation of categorical forecasting.
Future Improvements
• Develop best practices for the use of QPF in
KINEROS.
• COMET grant with University of Arizona, USDAARS, and Penn State to couple a sub-surface
lateral flow model and snow model with KINEROS.
Questions / Comments?