Updated: 1 December 2007

2.2.2 Roads Vs Linear Features Example 4

Location of Example: 152°19'30" East, 24°56'35" South
Distinctive Characteristics:
  • Drains/Canals can be differentiated from Roads as they do not provide connectivity to the existing road network.
  • If the Drain/Canal is completely dry it will appear lighter, similar to the surrounding soil and vegetation. The the edges will often appear much lighter, due to the excavated soil from construction.
  • Drains generally start at a water source and can end at a Reservoir, Water Tank or Sea.
  • Drains follow the topography of the land whereas roads may traverse hills and valleys.
  • In Figure the canals appear as dark blue linear bodies when filled with water.
  • The use of multispectral imagery band combinations can aid in the interpretation and differentiation of water.
Regional Considerations:
  • In areas where there is irrigated crop farming Canals/Drains appear as regular structured networks which show a water flow hierarchy diminishing from source. They are often aligned with paddocks and have access tracks or roads running parallel to them.
Figure: Representation of Canals.

Figure: Orthophotography 40cm RGB=123 Figure: SPOT Pseudo-natural 2.5m

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