Flood path of least resistance

Auckland Council will begin overland flow path assessments and flood resilience checks in Warkworth and Snells Beach next month as part of its Making Space for Water programme.

Overland flow paths are the natural routes rainwater takes across land during heavy rain, when drains are full, and are a normal and necessary part of the stormwater system to help prevent flooding of homes and streets.

Councillor Greg Sayers said flood resilience was a shared responsibility.

“By working with residents to identify risks early and keep overland flow paths clear, we can reduce flooding and better protect homes and neighbourhoods during heavy rain,” he said.

Council staff and contractors will visit selected properties in areas identified as higher flood risk.

Properties will be sent notification letters before the visit. The assessments focus on what is happening on the ground and will help identify where simple changes may reduce flooding risk.

Council’s overland flow path assessment programme lead Dean Yee for Auckland said seemingly small maintenance issues could add up quickly during heavy rain.

“During a storm, a single downpipe can release about four litres of water every second – that is a full 10-litre bucket every three seconds,” Yee said. “Multiply that across a neighbourhood and it is easy to see how small issues can become major flood risks.”

Where issues are identified, residents will receive advice on steps they can take that can help, such as keeping gutters and drains clear or adjusting fences so water can pass underneath. In many cases, no action will be needed.

Council said the aim was to support property owners, not penalise them.

“By working together, small changes on individual properties can make a real difference reducing flood risk and protecting homes and neighbourhoods during heavy rain.

“When these paths stay clear, water can move safely away. When they are blocked by fences, landscaping or debris, flooding can happen more quickly and with more damage.”

Since the programme started in 2024, council has visited more than 3500 properties across the region to assess overland flow paths.

The most common issue identified, affecting around half of the properties visited, was damaged or poorly maintained roof gutters and downpipes. When this is repeated across a neighbourhood, it can significantly increase the amount of water flowing over land instead of through the drainage system.