Description

With urban densification putting a strain on infrastructure services, some councils now require stormwater to be dealt with in situ, easing the strain on public systems.

For any building or development site, the area of ground able to absorb rainfall is reduced by the roofs of buildings and hard surface areas such as driveways and paving. The soil type also influences how much and how quickly water can be absorbed.

This means that water previously absorbed on an undeveloped site is typically discharged into a council stormwater system instead. The increasing density of urban and suburban development has significantly increased the stormwater load on public utilities.

Scope

This article includes the following parts:

• Move to hydraulic neutrality
• Stormwater flood management varies
• What causes stormwater flooding?
• Managing stormwater run-off
• Kapiti Coast case study
• No additional hazard from developments
• Ways to achieve hydraulic neutrality
• Auckland design approach
• Christchurch guidance
• Changes needed in designs