Loving Our Stormwater Gullies
The many gullies in the Taupō District, particularly those in urban areas, play an important role in stormwater management.
Good stormwater management is important as it can help prevent homes from being flooded during heavy rainfall events. Thanks to climate change, the frequency of these weather events is increasing. That’s why looking after and loving the district’s gullies has never been more important.
Gullies are also valued as recreation areas. Many people enjoy walking, biking, and exploring them.
However, some people value them much less. They are often used as dumping grounds for rubbish, lawn clippings, and green waste, which cause huge problems with weeds leading to the gullies becoming populated by undesirable species such as cherry trees, pine, and silver birches.
While native species planted on gully sides and banks help hold the banks together, some of the weed species can do more damage than good.
As well as acting as stormwater soakage areas, gullies are important for helping filter stormwater and prevent lakeshore erosion by slowing runoff into the lake. However, it’s always good to remember that they do lead directly to the lake, and not everything drains away.
Taupō District Council parks and reserves manager Greg Hadley says people often misunderstand the role of stormwater gullies.
“Gullies are created by nature to deal with water, and that’s what we need to let them do.
“We get a lot of requests for the gullies to be mown, and for plants on the edges of the banks to be trimmed or removed for people’s views. But actually, their job is preventing stormwater flooding and for that reason, long-rank grass is better than short grass. For the same reason, plants on the gully sides should be allowed to flourish, not manicured, because they are doing a job of protecting the bank’s soil by slowing down the water and allowing soakage. The root systems of plants can also slow soil migration”
Greg says most cases of gully bank erosion, where the edge of the gully creeps closer to the surrounding houses, are caused by human activity.
“Gully slips are often of the residents’ own making. Be careful about what you do about vegetation removal or vegetation trimming because that tree you’re trying to kill or trim may be providing some soil stability.”
Soil conservators describe Taupō soils as overly free-draining, highly mobile, and low in fertility, so be careful about water management on your property as it can lead to surface erosion or it can track underground creating tunnels or tomos (holes).
Greg says there’s an increasing awareness of the importance of planting natives in the gullies and allowing them to flourish in their natural state.
“At the end of the day, our gullies play an important role in soaking up stormwater and we need to leave them as unmodified as possible to let them get on with their job.”