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Hydrologic%20Cycle

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Terrain analysis using Digital Elevation Models. Flood hydrology model ... Hog Pen Ck. 4 km. 4 km. Watershed Delineation by Hand Digitizing. Watershed divide ... – PowerPoint PPT presentation

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Title: Hydrologic%20Cycle


1
Hydrologic Cycle
2
Hydrologic Cycle Processes
Processes
Precipitation Evaporation Surface
Runoff Groundwater Recharge Baseflow
Surface Water
3
Map-Based Hydrology and Hydraulics
ArcView Input Data DEM
ArcView Flood plain maps
CRWR-PrePro
AvRAS
HEC-RAS Water surface profiles
HEC-HMS Flood discharge
4
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

5
Study Region in West Austin
Hog Pen Ck
4 km
4 km
6
Watershed Delineation by Hand Digitizing
Watershed divide
Outlet
Drainage direction
7
30 Meter MeshStandard for 124,000 Scale Maps
8
DEM Elevations
720
720
Contours
740
720
700
680
680
700
720
740
9
Eight Direction Pour Point Model
10
DEM Elevations
Contours
700
680
11
Austin West 30 Meter DEMElevations in meters
ftp//ftp.tnris.state.tx.us/tnris/demA.html
12
Flow Direction Grid
13
Grid Network
14
Flow Accumulation Grid
0
0
0
0
0
0
0
0
0
0
0
3
2
2
0
0
3
2
0
2
0
0
1
0
0
11
0
1
0
11
0
0
0
1
15
0
0
1
0
15
1
0
2
24
5
2
5
0
1
24
15
Flow Accumulation gt 5 Cell Threshold
16
Streams with 200 cell Threshold(gt18 hectares or
13.5 acres drainage area)
17
Watershed Draining to This Outlet
18
Watershed and Drainage Paths Delineated from 30m
DEM
Automated method is more consistent than hand
delineation
19
DEM Data Sources
  • Digital terrain models with 2 or 4 contours
    built from aerial photogrammetry
  • 10m DE-DEMs, from 124,000 scale maps with
    drainage enforcement (experimental)
  • 30m DEMs from 124,000 scale maps
  • 1 " seamless DEM of Texas (March, 1999)
  • 3" (100m) DEMs from 1250,000 scale maps (current
    state-wide coverage)
  • 30 (1km) DEMs global coverage

20
Coverage of DEMs
1 seamless DEM
3" (100m) DEM

30m DEM
7.5
7.5

21
Cell Size
30m (1)
100m (3)
22
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

23
Map-Based Hydrology and Hydraulics
ArcView Input Data DEM
ArcView Flood plain maps
CRWR-PrePro
AvRAS
HEC-RAS Water surface profiles
HEC-HMS Flood discharge
24
Austin Digital Elevation Model
Waller Creek
25
Austin Watersheds
26
CRWR-PrePro
Digital Elevation Model Stream Map
ArcView-based preprocessor for HEC-Hydrologic
Modeling System (HEC-HMS)
Control point locations
Soil and Land Use Maps
HMS Basin File
27
DEM Watersheds for Austin
28
Selected Watersheds and Streams
Mansfield Dam
Colorado River
29
HMS Schematic Prepared with CRWR-PrePro
Mansfield Dam
Colorado River
30
  • 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.

31
HMS Basin File
Basin file is a text description of all
hydrologic elements
155
33
87
39
Subbasin
Reach
Junction
32
HMS Model of the Austin Region
33
Design Precipitation Input
34
Maps Served on the Web
35
Nexrad Rainfall for Storm of Oct 1994
36
HMS Results
Watershed 155
Junction 44
37
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

38
Map-Based Hydrology and Hydraulics
ArcView Input Data DEM
ArcView Flood plain maps
CRWR-PrePro
AvRAS
HEC-RAS Water surface profiles
HEC-HMS Flood discharge
39
Waller Creek DEM
40
Waller Creek HMS Model
41
Flood Plain Mapping
42
Connecting HMS and RAS
43
Discharge at a Particular Cross-Section
44
Map-Based Hydrology and Hydraulics
ArcView Input Data DEM
ArcView Flood plain maps
CRWR-PrePro
AvRAS
HEC-RAS Water surface profiles
HEC-HMS Flood discharge
45
HEC-RAS Background
  • River Analysis System model of the U.S. Army
    Corps of Engineers
  • Input cross-section geometry and flow rates
  • Output flood water elevations

Cross-Section Schematic
46
HEC-RAS Cross-Section Description
  • Points describe channel and floodway geometry
  • Bank station locations
  • Water surface elevations and floodplain
    boundaries

47
HEC-RAS Output
  • Graphical
  • Text File

48
HEC-RAS Data Translation
  • Data translation from HEC-RAS text file to dbase
    table
  • Bank and floodplain boundaries measured from
    stream centerline

49
Digital Stream Mapping
  • Digital orthophotograph and road coverage used as
    a base map
  • User digitizes stream with mouse
  • Boundary points define the RAS stream

50
Floodplain Mapping Plan View
51
3D Terrain Modeling Ultimate Goal
52
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

53
Real-time flood emergency mapping
Nexrad radar rainfall input
Real time
Precomputed flood map library
Offline
Flood hydrology analysis system
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