Impervious surface

Impervious surface overview

Summary of indicator

Objective

To measure the imperviousness of a given area, which is an important factor when considering drainage of water, particularly within urban areas.

Application guidance

Impervious surfaces impede the filtration of water into the soil and are mainly artificial structures such as pavements, roads and buildings. Pervious surfaces, on the other hand, are any porous and permeable area able to allow water to percolate into the soil and recharge the water table. Having a higher percentage of pervious areas have many environmental benefits such as delaying runoff peaks, increasing groundwater discharge, improving runoff quality, and reducing peak discharge volumes. The mapping of impervious surfaces is increasingly sought by land use managers to assess options for protecting waterways and other water dependent ecosystems.

This indicator will support practitioners to understand the level of imperviousness in suburbs across the state. Based on the outcome of the assessment, practitioners can determine the drainage capacity of each suburb and measure the environmental impacts of current developments and support the implementation of Water Sensitive Urban Design (WSUD) and low impact development technologies.

Practitioners can use the percentage of impervious surface metric to measure how much of a suburb is comprised of impervious surface materials.

Metric

Percentage of impervious surface

Related indicators

	Green and Blue Tree canopy Biodiversity Waterways
	Comfort and Safety Urban heat

Recommendation

To enrich the analysis of imperviousness, consideration for varying catchment characteristics of terrain, soil type, geology, vegetation and rainfall patterns could be included.

Metric in detail

Map