The Graphic Overlay Method

Creating Value Added Maps
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Value Added Maps  |  Elevation Maps  |  Soil Survey Maps  |  Soil Attributes
Soil Characteristics  |  Combining Strategy  |  Process Map  |  Solution Map

It's More Than Just A Map...!

Value Added Mapping techniques are deliberate enhancements to map cartography which are applied to intensify existing, (but not always apparent) physical, biological, and/or social-cultural features.  Value added mapping techniques are learned skills that help isolate, organize, extract, or combine map features.  These skills are particularly useful when preparing or organizing information for Graphic Overlay.

Value Added Data Map sets are appropriate collections of map and attribute information that collectively relate the significant map elements for a given area.  There are potentially thousands of data set variations, each particularly adapted to the needs of the Graphic Overlay Method user.  

Typical uses for the Value Added Topographic and Soils maps

Topography  Value added elevation maps portray the relative topographic elevation above mean sea level.  The graphic portrayal of the characteristics of land relief represented as topological (contour) lines on a map.  Topographic or Elevation maps are used in determining:  
  • Elevation at which flooding might occur. 
  • Elevation at which snow accumulates.
  • Avalanche prevention strategies.
  • Automobile traffic routing.
  • Emergency evacuation planning.
  • Elevation at which trees stop growing. 
  • Elevation at which breathing is difficult. 
  • Depth of navigable waterways. 
  • Effect of lake rise during flood season. 
  • Effect of wetland loss. 
Value added aspect maps characterize land solar orientation in terms of North, South, East, or West. Aspect maps are effective in determining:  
  • Soil moisture loss in agriculture and forestry. 
  • Energy effeciency in housing allocations. 
  • Indigenous vegetation habitats. 
Value added slope maps depict the relative measure of topographic steepness. 
Slope maps are useful in determining: 
  • Mass wasting potential. 
  • Landslide and rockslide potential. 
  • Avalanche potential. 
  • Soil erosion potential. 
Value added landform maps are graphic characterizations of the unique land surface qualities.  Landscapes are usually a mosaic of depositional, diastrophic, erosional, or residual classifications.   
Landform maps are worthwhile for determining:   
  • Physiologic regions. 
  • Land surface roughness. 
  • Indigenous vegetation and habitat. 
  • Visual character. 
  • Regional identity. 

SOILS  The regolith or surface materials of the landscape supports the growth of plants.  Soil maps are perhaps the most serviceable in beginning GIS application. The attribute tables for soil information is generally clear, and have a structure that can easily be directed in GIS to produce very practical maps such as:.  

Value added depth to bedrock maps are estimates of soil thickness above bedrock affecting:   

  • The cost of building foundation construction. 
  • The cost of road bed construction. 
  • The vegetative diversity. 
  • The indirect visual character. 
Value added depth to watertable map estimate the soil thickness above ground wholly saturated with water affecting:  
  • The cost of building construction. 
  • The cost of road construction. 
  • The vegetative vigor and diversity. 
Value added soil texture (soil class) maps incorporate the unified soil classification system by segregating soil components into sand, silt, clay divisions. This classification system is useful in determining:  
  • Appropriateness for building materials. 
  • Material incorporation potential within the construction process. 
Value added soil permeability maps display the ability of water to pass thru soil and affecting:   
  • The interval in agricultural cultivation. 
  • The timing in agricultural irrigation. 
Value added percolation rate maps demonstrate the measurement of time for water to pass thru the small pores within soils effecting, for example, septic tank suitability studies.  

Value added engineering constraints maps delineate negative characteristics of land and water features that can / might / will affect the planning phase of engineering. Engineering constraints maps influence the construction process and help determine the relative difficulty associated with the actual construction costs.  

Value added availability for construction materials sources of on site (or near by) construction materials such as topsoil, sand & gravel, and road fill. These maps help reduce over all costs, and provide for secondary opportunities in visual amenities, recreational opportunities, and wildlife habitat.  

Other Possible Value Added Maps:  (not used in the coming example)  
  • HYDROLOGY The water components of the landscape. 
  • VEGETATION The vegetative agricultural and silvacultural landscape components. 
  • HISTORICAL The cultural elements of the landscape. 
  • EXISTING LAND USE The current uses or activities of the landscape. 
  • PUBLIC and PRIVATE UTILITIES Municipal and private utility services such as electric, gas, sewer, and water. 
  • EXISTING ZONING The legal land activity partitions. 
  • TRANSPORTATION All methods of human circulation. 
  • ACCESSIBILITY How far is the particular activity or location from another activity or location.

Keep in Mind..., 
  • Value is a descriptive term that classifies the relative worth, utility, or importance of selected map features within a given area.  
  • Value is also a numeric quantity, (assigned or computed), that can define the amount, extent, or specific measurement of any given location. 

The Elevation Maps are the first of two examples that will demonstrate value added maps.  Or look at the Soil Survey Maps, (the second map in this example). 
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All contents copyright (C) 1993-1999,  D. Fehler  All rights reserved.