dem’s, watershed and stream network delineation dem data sources study area in west austin with a...
TRANSCRIPT
![Page 1: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/1.jpg)
DEM’s, Watershed and Stream Network Delineation
• DEM Data Sources • Study Area in West Austin with a USGS
30m DEM from a 1:24,000 scale map• Eight direction pour point model (flow
direction and flow accumulation grids)• Stream network definition• Watershed delineation
![Page 2: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/2.jpg)
DEM Data Sources
• Shuttle Radar Topography Mission (SRTM)
• 30m DEMs from 1:24,000 scale map
• 1” National Elevation Dataset
• 3" (100m) DEMs from 1:250,000 scale maps
• 30" DEM of the earth (GTOPO30)
![Page 3: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/3.jpg)
http://srtm.usgs.gov/srtmimagegallery/index.html
Santa Barbara, California
![Page 4: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/4.jpg)
http://srtm.usgs.gov/srtmimagegallery/index.html
San Andreas Fault, California
![Page 5: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/5.jpg)
http://srtm.usgs.gov/srtmimagegallery/index.html
Salt Lake City, Utah
![Page 6: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/6.jpg)
http://srtm.usgs.gov/srtmimagegallery/index.html
Mt Kilimanjaro, Tanzania
![Page 7: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/7.jpg)
Shuttle Radar Topography Mission (SRTM)
• 1 arc-second elevation data for the United States, 3 arc-second data for the globe
• Produced by radar measurements from a Shuttle mission, Feb 11-22, 2000
• http://srtm.usgs.gov/data/obtainingdata.html
![Page 8: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/8.jpg)
![Page 9: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/9.jpg)
Interferometry used by SRTMIn interferometry, two images are taken from different vantage points of the same area. The slight difference in the two images allows scientists to determine the height of the surface.
![Page 10: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/10.jpg)
SRTM Coverage 56°S to 60°N
![Page 11: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/11.jpg)
30m DEMs
• Best resolution standardized data source available for the US
• Coverage of the country is incomplete• Data by 7.5’ map sheets in UTM projection• Link for US
http://edcwww.cr.usgs.gov/Webglis/glisbin/guide.pl/glis/hyper/guide/usgs_dem
• Link for Texas http://www.tnris.state.tx.us/DigitalData/DEMs/dems.htm
![Page 12: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/12.jpg)
National Elevation Dataset
• Seamless 1” DEM for the US in 1° x 1° blocks
• Compiled by synthesizing the 30m DEM’s from 1:24,000 scale maps
• Link to website http://edcnts12.cr.usgs.gov/ned/
![Page 13: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/13.jpg)
Seamless Data Distribution
http://edcnts14.cr.usgs.gov/Website/store/viewer.htm
http://seamless.usgs.gov/
![Page 14: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/14.jpg)
7.5´
7.5´
1º
1º
1” and 3” DEMs
30m DEM
Coverage of 30m, 1” and 3" DEMs
![Page 15: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/15.jpg)
3” DEMs
• Derived by US Defence Mapping Agency, available from USGS for the whole US
• Data in geographic coordinates by 1;250,000 map sheet names (1ºx 1º) cells in (1ºx 2º) maps
• Needs to be projected to planar coordinates• Link http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html
![Page 16: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/16.jpg)
Cell Size30m 100m
![Page 17: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/17.jpg)
30" DEM GTOPO30
• Produced by USGS from 3" grids and Digital Chart of the World topography
• Coverage complete for the earth
• Projected cell size is 1km
• Data must be projected before use• Link http://edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html
![Page 18: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/18.jpg)
GTOPO30
Source: http://edcwww.cr.usgs.gov/landdaac/gtopo30/gtopo30.html
![Page 19: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/19.jpg)
Drainage in North America
Source: http://edcwww.cr.usgs.gov/landdaac/gtopo30/hydro/namerica.html
![Page 20: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/20.jpg)
Drainage Basins of North America
Source: http://edcwww.cr.usgs.gov/landdaac/gtopo30/hydro/na_basins.html
![Page 21: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/21.jpg)
DEM’s, Watershed and Stream Network Delineation
• DEM Data Sources • Study Area in West Austin with a USGS
30m DEM from a 1:24,000 scale map• Eight direction pour point model (flow
direction and flow accumulation grids)• Stream network definition• Watershed delineation
![Page 22: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/22.jpg)
Study Region in West Austin
Hog Pen Ck
4 km
4 km
![Page 23: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/23.jpg)
Topographic MapAustin West, 1:24,000 Scale
http://www.tnrcc.state.tx.us/gis/raster.html
20 ft contour
100 ft contour
Stream Center Line
![Page 24: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/24.jpg)
Flow in Direction of Steepest Descent
![Page 25: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/25.jpg)
Watershed Delineation by Hand Digitizing
Watershed divide
Drainage direction Outlet
![Page 26: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/26.jpg)
200 Meter Mesh (Universal Transverse Mercator Coordinates)
1km
1km
![Page 27: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/27.jpg)
100 Meter Mesh (UTM Coordinates)
100m
100m
1km
1km
![Page 28: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/28.jpg)
30 Meter MeshStandard for 1:24,000 Scale Maps
![Page 29: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/29.jpg)
Austin West 30 Meter DEMElevations in meters
ftp://ftp.tnris.state.tx.us/tnris/demA.html
![Page 30: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/30.jpg)
USGS 30 Meter DEM for This Area
![Page 31: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/31.jpg)
30 Meter DEM Cell Boundaries
![Page 32: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/32.jpg)
DEM Lattice Points
![Page 33: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/33.jpg)
DEM Cell Stores Elevation at Lattice Point
![Page 34: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/34.jpg)
DEM Elevations
Contours
720
700
680
740
680700720740
720 720
![Page 35: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/35.jpg)
DEM Elevations Contours
700
680
![Page 36: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/36.jpg)
DEM’s, Watershed and Stream Network Delineation
• DEM Data Sources • Study Area in West Austin with a USGS
30m DEM from a 1:24,000 scale map• Eight direction pour point model (flow
direction and flow accumulation grids)• Stream network definition• Watershed delineation
![Page 37: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/37.jpg)
67 56 49 46 50
12 11 12
53 44 37 38 48
58 55 22 31 24
61 47 21 16 19
3453
Digital Elevation Model
![Page 38: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/38.jpg)
67 56 49 46 50
12 11 12
53 44 37 38 48
58 55 22 31 24
61 47 21 16 19
3453
50
cell size
cell
(cell value)
Cell Definition
![Page 39: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/39.jpg)
32
16
8
64
4
128
1
2
Eight Direction Pour Point Model
![Page 40: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/40.jpg)
67 56 49
53 44 37
58 55 22
1
67 56 49
53 44 37
58 55 22
1
26.162
4467
14
1
5367
Slope:
Direction of Steepest Descent
![Page 41: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/41.jpg)
2 2 4 4 8
1 2 16
1 2 4 8 4
128 1 2 4 8
2 1 4 4 4
11
Flow Direction Grid
![Page 42: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/42.jpg)
Austin West 30 Meter DEMElevations in meters
ftp://ftp.tnris.state.tx.us/tnris/demA.html
![Page 43: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/43.jpg)
Flow Direction Grid
32
16
8
64
4
128
1
2
![Page 44: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/44.jpg)
Grid Network
![Page 45: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/45.jpg)
DEM’s, Watershed and Stream Network Delineation
• DEM Data Sources • Study Area in West Austin with a USGS
30m DEM from a 1:24,000 scale map• Eight direction pour point model (flow
direction and flow accumulation grids)• Stream network definition• Watershed delineation
![Page 46: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/46.jpg)
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
Link to Grid calculator
![Page 47: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/47.jpg)
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
![Page 48: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/48.jpg)
Stream Network for 5 cell Threshold Drainage Area
0 0 000
0
0
0
0
0
0
0
0
03 2 2
111
115
2 5
241
![Page 49: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/49.jpg)
Streams with 200 cell Threshold(>18 hectares or 13.5 acres drainage area)
![Page 50: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/50.jpg)
+ =
Take a mapped stream network and a DEM Make a grid of the streams Raise the off-stream DEM cells by an arbitrary elevation increment Produces "burned in" DEM streams = mapped streams
“Burning In” the Streams
![Page 51: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/51.jpg)
Filling in the Pits
• DEM creation results in artificial pits in the landscape
• A pit is a set of one or more cells which has no downstream cells around it
• Unless these pits are filled they become sinks and isolate portions of the watershed
• Pit filling is first thing done with a DEM
![Page 52: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/52.jpg)
![Page 53: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/53.jpg)
DEM’s, Watershed and Stream Network Delineation
• DEM Data Sources • Study Area in West Austin with a USGS
30m DEM from a 1:24,000 scale map• Eight direction pour point model (flow
direction and flow accumulation grids)• Stream network definition• Watershed delineation
![Page 54: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/54.jpg)
Watershed Outlet
![Page 55: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/55.jpg)
Watershed Draining to This Outlet
![Page 56: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/56.jpg)
Watershed and Drainage Paths Delineated from 30m DEM
Automated method is more consistent than hand delineation
![Page 57: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/57.jpg)
0 0 000
0
0
0
0
0
0
0
0
03 2 2
111
115
2 5
241
Stream Segments
![Page 58: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/58.jpg)
55
11
1
3
22
334 4 4
4 45
5
666
Stream Segments in a Cell Network
![Page 59: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/59.jpg)
9895101504 (>1000)
1000 Cell Threshold Exceeded at Stream Junction
![Page 60: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/60.jpg)
Same Cell Value
Subwatersheds for Stream Segments
![Page 61: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/61.jpg)
Vectorized Streams Linked Using Grid Code to Cell Equivalents
VectorStreams
GridStreams
![Page 62: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/62.jpg)
Delineated Subwatersheds and Stream Networks
![Page 63: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/63.jpg)
Summary Concepts
• Topographic maps are the traditional way of representing land surface terrain and streams
• Watersheds can be hand-delineated from these maps
• DEM’s of equivalent accuracy are now available for most map series in the US
![Page 64: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/64.jpg)
Summary Concepts (2)
• DEM cell elevation is at the cell center
• eight direction pour point model leads to flow direction and flow accumulation grids
• stream network is defined as cells whose flow accumulation exceeds a threshold
• watershed outlet is the cell with highest flow accumulation
![Page 65: DEM’s, Watershed and Stream Network Delineation DEM Data Sources Study Area in West Austin with a USGS 30m DEM from a 1:24,000 scale map Eight direction](https://reader035.vdocument.in/reader035/viewer/2022062314/56649e4c5503460f94b41c6c/html5/thumbnails/65.jpg)
Summary Concepts (3)
• Streams can be divided into links and subwatersheds defined for them
• Resulting grids can be vectorized
• Standardized DEM data sources: 30m, 1” 3”, 30”
• Coverage from local scale to the whole earth