To help predict the impact of possible changes in zoning and future development, the City Development Research and Monitoring team track a number of elements across the city. One of these is the amount of surface impermeability (land which cannot absorb water).
The latest aerial imagery of Dunedin has been used to determine the amount of land covered by vegetation (considered permeable) and the amount of land not covered by vegetation (considered impermeable).
To do this we used a Geographic Information System (GIS) tool that allows aerial photographs to be classified into different categories depending on the combination of the red, green, blue and near-infrared wavelengths reflected by objects.
While many urban structures will reflect different combinations of red, green and blue light, healthy vegetation will also reflect near-infrared light. This light, while invisible to humans, is visible to the cameras used for aerial photography.
The map below shows impermeability across the urban area, as well as a summary layer outlining the proportion of different areas that is impermeable.
For further information, contact the Research and Monitoring team at research.monitoring@dcc.govt.nz or on 477 4000.