Figure 2.22 Overlay Mapping

Figure 2.22 Overlay Mapping

Source: Author elaboration (Sebastian Moffatt), with assistance from Metro Vancouver GIS Department. Note: In this example of overlay mapping, multiple infrastructure systems have been layered onto a single map to depict the location of manufactured capital assets. This information may also be useful in land use planning and in optimizing the use of existing infrastructure systems.

natural gas and electricity infrastructure systems and the major transportation routes for rail and road are already exposed to signifi cant risk because they are located in the fan of projected debris from landslides off the east slope of the mountains. Even the electrical substation has been incorrectly located in this hazardous area because of the lack of prior overlay mapping.

Another example of innovation in overlay mapping is the collection of maps in fi gure 2.24, which displays a series of maps for the same Squamish region. Each map focuses on a different renewable energy asset. By overlaying the energy asset maps, one produces a tool that makes it easier to plan development based on local renewable energy resources. For example, a new residential development may be located in areas in which the sunshine permits yearlong use of solar water heaters and in which new buildings stay clear of the windy ridge north of town, where average wind speeds are suffi cient to support a wind farm.

It is not unusual for land use and infrastructure plans to proceed without any reference to the risk of natural disasters or to other critical landscape relationships such as local resource assets, ecological functions (such as rainwater catchment, food production, and wind protection), and unique or ecologically sensitive areas that contribute to local biodiversity and ecological health. Design teams and policy experts are able to adapt their policies and designs to this information only if it is available in a timely and easy-to-understand format.

A more common and especially useful application of overlay mapping involves mapping the capacity of existing infrastructure and comparing this with the projected demand for services. Many urban regions are now using this type of overlay mapping to assist in growth management. Areas with surplus capacity within their infrastructure systems are the most appropriate locations for new development or infi ll, all other factors being equal. Areas with especially high demand may be appropriate for localized infrastructure systems; for example, high energy demand makes district energy systems cost-eff ective. Because maps are available on such areas, one may more easily implement the policies that make buildings suitable for hooking up to a local network. This kind of forward-looking policy helps create a municipal ecology in which many