TWCA Mid-Year Conference 2018

1. Development of a Early Flood Warning
Tool Set for Bandera County, Texas
Doug Schnoebelen, PhD
Associate Director, South Texas
Program Office, San Antonio, TX
U.S. Geological Survey, Texas Water
Science Center
Texas Water Conservation Association (TWCA), June 12-15, 2018

2. USGS real-time
streamgage
information is used
across the Nation for
both flood and
drought assessments
Floods and Drought

3. South Texas Program Office Coverage
• 208 Stream/Lake sites
• 18 Water quality sites
• 8 Groundwater sites
Real time sites

4. Developing integrated
systems of stream
gages, rain gages,
modeling and cameras
for complex issues
Flood Warning—
An Integrated
Systems
Approach

5. Flooding in the Texas Hill Country
“Flash Flood Alley”
Examples from Blanco Basin and
Bandera County, TX
“New Tools”

6. Physical Characteristics
Texas Hill
Country
Spring fed
Stony hills and
steep canyons
Thin layer of
topsoil

7. Wimberley

11. Blanco River @ FM165

12. Planning for a Flood—Three key points
to consider
• What areas will be flooded?
• How deep will the waters get?
• When will the flood arrive?

13. Improved
Technology
& Network
Approach

16. Stream Selection (flood areas)

17. Modeling Flood Heights (flood depths)

18. Geospatial Processing (flood extent)

19. Creation of Flood Inundation Maps
Hydraulic Modeling
Geospatial Processing
Series of sequential
maps showing probable
areas of flooding (Flood
Atlas)

20. FIM Web Mapping Application
FIM—”Flood Inundation Mapping”

21. Early Model Results--Bandera
Flood Categories (in feet)
USGS 1% Annual Exceedance Flood
Major Flood Stage: 24
Moderate Flood Stage: 14
Flood Stage: 13
Action Stage: 10

22. Flood Categories (in feet)
FEMA FIRM 1% Annual Exceedance Flood
USGS 1% Annual Exceedance Flood
Major Flood Stage: 24
Moderate Flood Stage: 14
Flood Stage: 13
Action Stage: 10

23. y = 0.9956x + 5.2527
R² = 0.9947
WSE RMS = 0.48 ft
(Rating - Model)
1195
1200
1205
1210
1215
1220
1225
1230
1195 1200 1205 1210 1215 1220 1225 1230
Modeledwatersurfaceelevationat
Bandera,inNGVD29feet
Rated water surface elevation at Bandera, in NGVD29 feet
Modelled
Calibrated
1 to 1
Linear (Calibrated)
Flood Categories (in
feet)
Major Flood Stage: 24
Moderate Flood Stage: 14
Flood Stage: 13
Action Stage: 10
Early Model Results

24. New Tools and Technology--Bandera
LSPIV
Calculates 2D velocity for the
viewable scene.
Instantaneous or averaged.
Grid of vectors for a ROI.
Discrete measurements.
Foam, surface patterns, no standing waves
IMAGE Velocimetry (Large
Scale Particle Image
VelocimetryDOPPLER RADAR Velocimetry
RADAR
Calculates 1D velocity
time. Spectra of return
signal amplitudes give
velocity (Doppler shift) and
SNR.
X X X
Moving surface waves > 3 mm, no
standing waves
SENSE
PROCESS
DERIVE
VELOCITIES

25. Video Cameras &
LSPIV—Hurricane
Harvey Examples
• Collected daily videos
during the drawdown
releases from the reservoirs
from Sept 5–12, 2017
• Analysis estimated
velocities “on demand” for
USACE
Preliminary Information-Subject to Revision. Not for Citation or Distribution.

26. Drone-Based
Mapping
Plan and fly, then make
maps, DEMs, and more…

27. Drone-Based Mapping
Go from photos3D Point
CloudsDEMs /
LASextractions/classification

28. Early Flood Warning Tools—New
Technology, Equipment & Modeling
– Preparedness
• “What-if” scenarios
– Response
• Tied to gage & forecast
data
• Road/Bridge Closures
– Recovery
• Damage Assessment
– Flood Atlas
• Working with Emergency
Managers and Planners
Photo Courtesy of Jerry Sides
Medina Lake - 2002

29. Questions?
USGS
“Best in Science
Best in Service”
Doug Schnoebelen, PhD
USGS, San Antonio, TX
210-691-9262
dschnoebelen@usgs.gov
tx.usgs.gov