Feature Measurement

Features  |  Feature Listing  |  Feature Measurement

What are the quantities of each map feature?

Map features are measured in individually appropriate units that best represent the land (or water) activity or use. The typical units of measure are frequency, size, color, height, weight, uniqueness, and capacity. Here are a few examples (of course), there are numerous features and forms of measurements not listed here.

Climate Measurements

Driest monthly precipitation – inches/month
Fog Visibility – the distance in feet
Frost Thickness – thickness in inches
Ground radiation – 
Soil temperature – degrees Fahrenheit
Maximum 24-hr. precipitation – inches/day
Maximum 24-hr. snowfall – inches/day
Mean annual precipitation – inches/year
Mean annual snowfall – inches/year
Mean annual temperature – degrees Fahrenheit
Mean monthly temperature – degrees Fahrenheit
Mean relative humidity – percent air saturation
Number of days of precipitation – days (w and w/o)
Potential evapotranspiration – inches (loss) precipitation.
Solar radiation – air temperature in degrees Fahrenheit
Storm systems – direction and speed of travel
Surface air drainage – temperature (F.) and flow rate (cfs)
Temperature (air) – degrees Fahrenheit
Wettest monthly precipitation – inches/month
Wind, direction – (N, S, E, W), and speed (mph)

Geology

Building materials – Cubic yards (sand and gravel)
Depth to bedrock – Depth from the ground surface in feet
Economic minerals – Depth (feet), overburden (tons),
Landform types – Most rare to least rare (Uniqueness)
Landslide potential – Probability of occurrence (high/low)
Rock outcrops and ridges – Percent slope, and visual quality
Rock types – Percent of Sandstone, Limestone, Shale
Stability of bedrock – Fracture potential
Structural characteristics – Hardness, weathering properties
Unique land formations – Most unique to least unique
Unstable land formations – Most stable to least stable
Volcanic activity – Probability of occurrence (high/low)
Weathering properties – physical, chemical and biological
Erosion potential, and severity – soil loss in acres

Soils Measurements

Bearing capacity – Pounds per square foot
Erodability – Most susceptible to least susceptible
Instability – High risk to low risk
Internal drainage – Volume (cfs), length (ft.)
Permeability – Very permeable to not permeable
Productivity – Highly productive to not productive
Soil erosion – Tons/year
Soil type – Classification by unique properties
Soil depth – By A, B, C-Horizon, strata in feet
Soil texture – V. coarse to V. fine particle size
Stoniness – Size and frequency per square foot
Wetness hazard – High possibility to no possibility.

Topographic Measurements

Contour interval – Feet or Meters
Elevation – Height (in ft.) above mean sea level
Length of contour lines – Miles
Mean basin elevation – Feet
Orientation – Aspect: North, South, East, West
Relief variation – Variation of vert./horizontal ratio
Slope rim – Location, aspect, and length in miles 
Slopes – Ratio of height/length in feet

Water Measurements

Aquifer recharge – Thousands of gallons per second
Bayous – Visual quality, wildlife quality, more
Biological productivity – Highly productive to not productive
Drainage density – Fine, medium, and coarse
Drainage patterns – Water energy potential in ft. lbs.
Edge stability – 
Erosion potential – 
Flood potential – Frequency of occurrence, water depth
Gage elevation – Feet
Groundwater depth – Feet from the surface to potable water
Groundwater quality – Clarity (vis. depth), turbidity
Groundwater recharge – Potential for recharge
Groundwater contamination – Potential for the occurrence
Lakes – Size in acres, depth in feet,
Length of streams – Miles
Length of tributaries – Miles
Mainstream length – Miles
Mean annual flood – Cfs/square mile
Rivers – Length/depth in feet
Shoreline use (activities) – People per day
Shoreline quality – Absence or presence of trash
Springs – Volume in gallons per minute
Streams – Flow rate in feet per second
Stream slope – Vertical change in feet/mile
Water clarity – Dissolved solids Parts per milligram Suspended solids Size in mm.
Water quality (surface) – Visual, smell, clarity, taste, sediment load, etc.
Water temperature – Degrees Fahrenheit
Waterfalls – Height and width in feet
Watersheds – Square miles
Watershed slope – Feet per mile
Wetlands – Visual quality, and wildlife habitat potential.

Vegetation Measurements

Agricultural – Acres, productivity (active/abandoned)
Composite land cover – Acres/landcover category
Edge communities – Number and variety of species, uniqueness
Fields – Acres, wetness hazard, productivity
Forests – Acres, productivity
Natural associations – Uniqueness of species
Overstory type – Species type, height, density
Understory type – Shade tolerance, diversity
Pastures – Animal grazing months
Riparian communities – Uniqueness of species, acres/miles
Sources of bldg. materials – Quantity in board feet
Sources of heating fuel – Volume in chords
Specimen areas – Most to least vulnerable
Vegetation type – Species names
Vegetation quality – Age class, uniqueness, visual quality

Wildlife Measurements

Major ecotones – Indicator species, uniqueness
Primary habitats – Acres of forage, species variety
Unique areas – Most rare to least rare
Wilderness areas – Acre size, species diversity
Wildlife types – Species variety
Wildlife habitats – Contiguous acres, pathways, and travel way linkages

Typical Unit Conversions

All units of measure can be easily converted to more practical or more familiar units. GIS is not dependent on any specific units of measure, because “units” are easily converted or interchanged one unit to another.

To convert: [Acres] to [Hectares]
Multiply [Acres] by [.4047]

Acres to Hectares x [.4047 ]
Centimeters to Feet x [.0328]
Cubic feet to Cubic meters x [.0283] 
Gallons to Liters x [3.7853] 
Feet/Second to Meters/Second x [8.4667] 
Hectares to Acres x [2.4710] 
Feet to Meters x [.3048] 
Meters to Feet x [3.2808] 
Miles/Hour to Kilometers/Hour x [1.6093] 
Miles to Kilometers x [1.6093] 
Sq. Miles to Sq. Kilometers x [2.5899]