Elevation and Elevation Profiles A. Branscomb Hypsology
Transcript of Elevation and Elevation Profiles A. Branscomb Hypsology
PNW Ecosystem Research Consortium12
Elevation and Elevation Profiles
A
A’
B B’
C C’
W
W’S
N
Elevation Profile Locations
Not to scale
0˚
1˚ - 2˚
3˚ - 4˚
5˚ - 6˚
7˚ - 8˚
9˚ - 10˚
11˚ - 13˚
14˚ - 16˚
17˚ - 20˚
21˚ - 25˚
26˚ - 30˚
31˚ - 65˚
0 - 6%
2 - 4%
5 - 7%
9 - 11%
12 - 14%
16 - 18%
19 - 23%
25 - 29%
31 - 36%
38 - 47%
49 - 58%
60 - 214%
WRB percent slope WRB degrees slope
Figure 13. Willamette River Basin profiles. On the profiles above, el-
evations for cities and towns are derived from published sources, while
those for physical features are derived from the digital elevation model.
Vertical exaggeration is 30:1 for all profiles.
Figure 14. Calculating slope:
In the maps below, topographic slope is determined individually
for each 1/4 acre (30 meter x 30 meter) cell in the digital elevation
model. The slope is computed by reference to cells in a 3x3 matrix sur-
rounding the target cell. With the elevation of edge-touching cells
given twice the weight as that of corner-touching cells, the maximum
rate of change in elevation from the target to its neighbors, and its di-
rection, are calculated. The compass direction of this line is the topo-
graphic aspect of the target cell.
Slope is represented in two forms, percentage and degrees. De-
grees measure the interior angle of a triangle in which the base is the
“run” and the height is the “rise” along the direction of maximum el-
evation change for the cell. Percentage slope multiplies the rise/run ra-
tio by 100. An increasingly vertical line has degrees slope approaching
90, but a percentage slope approaching infinity as the “run” denomina-
tor goes to zero. A 45 degree slope is a 100% slope.
Distance (km)
Ele
vati
on
(m
)
0
500
1000
1500
2000
0 50 100 150 200
C
C'S. Yamhill R.
(37 m)
Willamette R.(23 m)
Molalla R.(108 m)
Clackamas R.(332 m)
Timothy Lake(984 m)
Woodburn(56 m)
0
500
1000
1500
2000
0 50 100 150
B
B'
Veneta(122 m)
Eugene(128 m)
Cougar Res.(518 m)
Horse Cr.(871 m)
0
500
1000
1500
2000
0 50 100 150 200 250 300
A
A'
Beaverton(58 m)
S. Santiam R.(260 m)
HeadwatersMiddle Fork Willamette R.
(1284 m)
Willamette R.(15 m)
McKenzie R.(290 m)
0
500
1000
1500
2000
0 50 100 150 200 250 300 350 400 450
W
W'
Portland(0 m)
Oakridge(345 m)
Lowell(212 m)
Eugene(122 m)
Corvallis(58 m)
Salem(34 m) Oregon City
(0 m)
distances are along channel.Elevations are at river level;
Hypsology
Hypsology is the study of the relative altitude of places. Map 3 on the
facing page is a hypsometric “hill-tint” in which elevation is depicted
through variations in color and brightness. The shading is rendered as if the
image were a topographic relief map illuminated by a source of light at 45
degrees above the map in the northwest corner, 315 degrees azimuth. It dif-
fers from true illumination in that higher features closer to the light source do
not cast shadows on those behind. No vertical exaggeration is applied.
A. Branscomb
Based on U.S. Geological Survey,32 U.S. Forest Service, and U.S. Bureau
of Land Management digital sources contained in an archive managed by the
Oregon Geospatial Data Clearinghouse,33 Map 3 was constructed from a digi-
tal elevation model made by joining approximately 300 individual 7.5 minute
quadrangle digital elevation models. Each of these is a rectangular matrix of
elevation values spaced 98.4 ft apart (30 m). Vertical accuracy varies from
+/- 24.6 ft (7.5 m) to +/- 49.2 ft (15 m) and horizontal accuracy conforms to
U.S. Geological Survey national map accuracy standards, which at this scale
means that 90% of values lie within 39.4 ft (12 m) of actual location.
θ
θ
θ
Percent slope = 58
Degree slope = 45Percent slope = 100
Degree slope = 60Percent Slope = 173
Degrees of slope =
Percent slope = rise/run X 100rise/run = tan θ
θ
Degree slope = 30
Unit Equivalences
Metric English
100 m 500 m1000 m1500 m
50 m
2000 m10 km50 km
100 km300 km500 km
164 ft328 ft
1640 ft3280 ft4921 ft
1.2 mi6.2 mi
31.1 mi62.1 mi
186.4 mi310.7 mi
LANDFORM
Willamette River Basin Atlas
2nd Edition
13
LANDFORMS
43°22’30"
43°30’00"
43°37’30"
43°45’00"
43°52’30"
44°00’00"
44°07’30"
44°15’00"
44°22’30"
44°30’00"
44°37’30"
44°45’00"
44°52’30"
45°00’00"
45°07’30"
45°15’00"
45°22’30"
45°30’00"
45°37’30"
45°45’00"
45°52’30"
43°22’30"
43°30’00"
43°37’30"
43°45’00"
43°52’30"
44°00’00"
44°07’30"
44°15’00"
44°22’30"
44°30’00"
44°37’30"
44°45’00"
44°52’30"
45°15’00"
45°22’30"
45°30’00"
45°37’30"
45°45’00"
45°52’30"123°45’00" 123°37’30" 123°30’00" 123°22’30" 123°15’00" 123°07’30" 122°45’00" 122°37’30" 122°30’00" 122°22’30" 122°15’00" 122°07’30" 122°00’00" 121°52’30" 121°45’00"
123°45’00" 123°37’30" 123°30’00" 123°22’30" 123°15’00" 123°07’30" 123°00’00" 122°52’30" 122°45’00" 122°37’30" 122°30’00" 122°22’30" 122°15’00" 122°07’30" 122°00’00" 121°52’30" 121°45’00"
S
N
0 mi 10 mi 20 mi
0 km 10 km 20 km 30 km
Projection UTM Zone 10
Scale 1:750000
Elevation (feet)
0 - 20
21 - 50
51 - 100
101 - 200
201 - 500
501 - 1000
1001 - 1500
1501 - 2000
2001 - 2500
2501 - 3000
3001 - 3500
3501 - 4000
4001 - 4500
4501 - 5000
5001 - 5500
5501 - 6000
6001 - 6500
6501 +
(meters)
0 - 6
6 - 15
16 - 30
31 - 61
61 - 152
153 - 305
305 - 457
458 - 610
610 - 762
762 - 914
915 - 1067
1067 - 1219
1220 - 1372
1372 - 1524
1524 - 1676
1676 - 1829
1829 - 1981
1982 +
Map 3. Hypsometry34