hydrologic cycle. hydrologic cycle processes surface water soil water atmospheric water groundwater...
TRANSCRIPT
Hydrologic Cycle
Hydrologic Cycle Processes
Surface WaterSoil water
Atmospheric water
Groundwater
Processes
Precipitation
Evaporation
Surface Runoff
Groundwater Recharge
Baseflow
Map-Based Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWatersurfaceprofiles
ArcViewFlood
plain maps
CRWR-PrePro AvRAS
GIS-Based Flood Modeling
• Terrain analysis using Digital Elevation Models
• Flood hydrology model for the Austin region
• Creating flood plain maps for Waller Creek
• Real time flood emergency management
Study Region in West Austin
Hog Pen Ck
4 km
4 km
Watershed Delineation by Hand Digitizing
Watershed divide
Drainage direction Outlet
30 Meter MeshStandard for 1:24,000 Scale Maps
DEM Elevations
Contours
720
700
680
740
680700720740
720 720
32
16
8
64
4
128
1
2
Eight Direction Pour Point Model
DEM Elevations Contours
700
680
Austin West 30 Meter DEMElevations in meters
ftp://ftp.tnris.state.tx.us/tnris/demA.html
Flow Direction Grid
32
16
8
64
4
128
1
2
Grid Network
0 0 000
0
0
0
0
0
0
0
0
03 2 2
11 1
1 152 5
24 1
0 0 00 0
0
0
0
0
0
0
0
0
0
3 2 2
11 1
1
12
15
245
Flow Accumulation Grid
0 0 00 0
0
0
0
0
0
0
0
0
0
3 2 2
11 1
1
12
15
245
Flow Accumulation > 5 Cell Threshold
Streams with 200 cell Threshold(>18 hectares or 13.5 acres drainage area)
Watershed Draining to This Outlet
Watershed and Drainage Paths Delineated from 30m DEM
Automated method is more consistent than hand delineation
DEM Data Sources• Digital terrain models with 2’ or 4’ contours built
from aerial photogrammetry • 10m DE-DEMs, from 1:24,000 scale maps with
drainage enforcement (experimental)• 30m DEMs from 1:24,000 scale maps• 1 " seamless DEM of Texas (March, 1999)• 3" (100m) DEMs from 1:250,000 scale maps
(current state-wide coverage)• 30” (1km) DEMs global coverage
7.5´
7.5´
1º
1º
3" (100m) DEM
30m DEM
Coverage of DEMs1” seamless
DEM
Cell Size30m (1”) 100m (3”)
GIS-Based Flood Modeling
• Terrain analysis using Digital Elevation Models
• Flood hydrology model for the Austin region
• Creating flood plain maps for Waller Creek
• Real time flood emergency management
Map-Based Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWatersurfaceprofiles
ArcViewFlood
plain maps
CRWR-PrePro AvRAS
Austin Digital Elevation Model
Waller Creek
Austin Watersheds
CRWR-PrePro
ArcView-based preprocessorfor HEC-Hydrologic ModelingSystem (HEC-HMS)
Digital Elevation ModelStream Map
HMS Basin File
Control point locations
Soil and Land Use Maps
DEM Watersheds for Austin
Selected Watersheds and Streams
Mansfield Dam
ColoradoRiver
HMS Schematic Prepared with CRWR-PrePro
Mansfield Dam
ColoradoRiver
• SCS Runoff Curve Number method determines the direct runoff from storm rainfall in small watersheds.
• Curve number (CN) is a function of hydrologic soil group and land use.
HMS Basin FileBasin file is a textdescription of all hydrologic elements
15533
8739Subbasin
Junction
Reach
HMS Model of the Austin Region
Design Precipitation Input
Maps Served on the Web
Nexrad Rainfall for Storm of Oct 1994
HMS Results
Watershed 155 Junction 44
GIS-Based Flood Modeling
• Terrain analysis using Digital Elevation Models
• Flood hydrology model for the Austin region
• Creating flood plain maps for Waller Creek
• Real time flood emergency management
Map-Based Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWatersurfaceprofiles
ArcViewFlood
plain maps
CRWR-PrePro AvRAS
Waller Creek DEM
Waller Creek HMS Model
Flood Plain Mapping
Connecting HMS and RAS
Discharge at a Particular Cross-Section
Map-Based Hydrology and Hydraulics
ArcViewInput Data
DEM
HEC-HMSFlood
discharge
HEC-RASWatersurfaceprofiles
ArcViewFlood
plain maps
CRWR-PrePro AvRAS
HEC-RAS: BackgroundRiver Analysis System model of the U.S. Army Corps of
Engineers
Input = cross-section geometry and flow rates
Output = flood water elevations
Floodway Floodway
Left Bank Station
Flood Water Surface
Right Bank Station
Normal Water Surface
Main Channel
Cross-Section Schematic
Points describe channel and floodway geometry
Bank station locations
Water surface elevations and floodplain boundaries
HEC-RAS: Cross-Section Description
HEC-RAS: OutputText FileGraphical
Data translation from HEC-RAS text file to dbase table
Bank and floodplain boundaries measured from stream centerline
HEC-RAS: Data Translation
Digital orthophotograph and road coverage used as a base map
User digitizes stream with mouse
Boundary points define the RAS stream
Digital Stream Mapping
Floodplain Mapping: Plan View
3D Terrain Modeling: Ultimate Goal
GIS-Based Flood Modeling
• Terrain analysis using Digital Elevation Models
• Flood hydrology model for the Austin region
• Creating flood plain maps for Waller Creek
• Real time flood emergency management
Real-time flood emergency mapping
Flood hydrologyanalysis system
Nexrad radarrainfall input
Precomputedflood map
library
Real time
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