Ashley River/Rakahuri vegetation clearance
The Ashley River/Rakahuri is a key feature of the North Canterbury landscape that poses a significant flood risk to the communities living on its floodplain. This project involves removing exotic vegetation (willow and brush weeds) choking a section of the river between Ashley Gorge and the Okuku River confluence, and in the Okuku River.
This vegetation is a flood and erosion risk, occupying the channel and forcing floodwaters towards farmland. Weed growth can also contribute to the loss of aquatic habitats and nesting areas for native birds.
The clearance area in this project is divided into two locations:
- Location 1: A 15-kilometre section of the Ashley River from Ashley Gorge (about 536ha)
- Location 2: An 8-kilometre section of the Ashley River, from the end of Location 1 to the Okuku confluence and approximately 7.5 km upstream in the Okuku River to just west of the Grey River confluence (about 140 ha).
Location 1 clearance complete
In March 2022 we completed the physical clearance of vegetation at Location 1. In this area whole trees with trunks down to approximately 100 mm diameter were removed. Trees immediately adjacent to active streams, smaller trees, stumps and brushweeds were not removed. We also conducted spraying with herbicide, that will be part of ongoing river maintenance.
The clearance of Location 2, up to the Ōkuku confluence was completed at the end of 2022. Works on the Ōkuku continue.
The Ōkuku River clearance involves a mix of weed control in densely vegetated areas and physical clearance, with trees removed by cutting and extraction. The river works are divided into two, with works in the upper area, in collaboration with Waimakariri District Council, due to begin in February 2023.
This project will have a significant impact on the flood resilience of communities living near the river as well as improve biodiversity values.
In addition, it’s another project that will address the risk to indigenous ecosystems and species from the enhanced spread, survival and establishment of invasive species due to climate change as outlined in the National Climate Change Risk Assessment.