Applied Geomorphology Lecture Noteslibvolume3.xyz/.../geomorphology/geomorphologynot… ·  · 2014-05-27Applied Geomorphology Lecture Notes By David T. Allison. Topographic Maps

Applied Geomorphology Lecture Notes

By David T. Allison

Topographic Maps

Scale (Relational Fraction; Graphical)Elevation contours (Relative to M.S.L)Boundary (Latitude & Longitude)Color (Water bodies, Woodlands, etc.)Cultural Features (man-made features)

Scale

Relational fraction 1:24,000 1 inch on the map = 24,000 inches in reality 1 inch on the map = 24,000 inches x 1 foot/12

inches 1 inch on the map = 2000 feet 1 inch on the map = 2000 feet x 1 mile/5280 ft 1 inch = 0.378 miles

Graphical Scale

Uses a graphical scale to indicate distances

Elevation Contours

Contour lines (brown) Based on aerial photographs analyzed

stereographically Must agree with benchmarks and spot

elevations Contour interval: elevation change between

adjacent contours Hachured contours indicate closed

depressions

Construction of Topographic Contours

Contours of any parameter use a simple proportionality ruleContours should “V” in the upstream direction across valleys.

x

xx

x80

80

87

77

flow

Topographic contours in 3D

Topographiccontours in 3D cont.

Contours: can delineate geological contacts

Topographic Map Boundary

Always consist of lines of latitude and longitudeContain tick marks of UTM and SPCS on the border 32 7’ 30’’

32 15’

103 22’ 30’’103 30’32 7’ 30’’

32 15’103 30’ 103 22’ 30’’

7.5’ TopographicQuadrangle border (1:24,000)

Topographic Map Colors

Brown: topographic contoursGreen: Forest and/or wetlandsWhite: cleared areas (i.e. pastures, etc.)Black: Cultural features (buildings, roads)Red: Land office grid system (Township & Range system); Major road systemsMagenta: Photo-revised areasBlue: water bodies

Topographic Map Examples

Map Coordinate Systems

Land Office Grid system (Township & Range)Universal Transverse Mercator (UTM)State Plane Coordinate System (SPCS)

Land Office Grid System

T1N

T2N

T1S

T2S

R1E R2ER1WR2W

State Capital

6 1

7 12

1318

19 24

2530

31

36 squaremiles

36

6 miles

NW NE

SE

Target location

Legal description of location:NE ¼ , SW ¼, section 22, T2S, R2E

Land Office Grid Example:Benchmark 212: NW ¼, NE ¼, sec.

36, T3S, R3W