CASE STUDY

Post-Earthquake Coastline Restoration

Kaikōura Coastline

Backstory:

On Monday the 14th of November 2016, a magnitude 7.8 earthquake shook the Kaikōura coastline. Mass land subsidence occurred along the Hikurangi subduction zone causing between 80,000 and 100,000 landslides with close to one million cubic metres of slip material collapsing onto the transport corridor below.

Disturbance caused by these landslides wiped out large areas of vegetation, leaving slip faces barren and exposed to erosion.

This disaster interrupted the economy of the South Island and isolated local communities. Since 2016, thousands of people and over one billion dollars have been invested to remediate the effects of this natural disaster.

"...devoid of vegetation, topsoil, and nutrients, presenting a challenge to re-establish flora onto these degraded clay and mineral substrates."

The Challenge:

NCTIR (North Canterbury Transport Infrastructure Recovery) was an alliance established to tackle the recovery efforts of both the road and surrounding areas.

An army of people, trucks, and diggers created multiple permanent stockpiles and engineered batters using the slip material removed from significant slips within the transport corridor. These stockpiles and batters were devoid of vegetation, topsoil, and nutrients, presenting a challenge to re-establish flora onto these degraded clay and mineral substrates.

Eco-sourcing plants to add aesthetic value to the newly established safe stopping areas and to stabilise engineered stockpiles and batters was a challenge due to the short timeframes and large volumes required.

The Solution:

Red Tree specializes in using eco-sourced native seed in post-natural disaster ecological restoration projects and was engaged to undertake a combination of traditional planting and Enviroblanket® applications along the damaged coastline.

A prescriptive coastal Enviroblanket® was designed to withstand the harsh environmental conditions presented in Kaikōura and to facilitate remediation of degraded substrates.

In 2018, Red Tree, in collaboration with other local nurseries, collected eco-sourced native tree and shrub seed within the Kaikōura ecological district. Invasive pest plant management was then undertaken in 2019 to prepare sites for planting and direct seeding.

In 2020, Red Tree traditionally planted more than 55,000 native plants and pneumatically installed approximately 4 hectares of Enviroblanket® across multiple sites within the corridor. In order to remediate a particular inaccessible slip site, Red Tree also developed and applied an aerial Enviroblanket® via helicopter.

Outcomes:

In areas with higher quality substrates, the Enviroblanket® has performed exceptionally well, exhibiting a broad range of species diversity and rapid establishment. These areas require minimal assistance to continue establishing.

Other areas with more difficult constraints have required nutrient support to assist growth and non-palatable species selection to mitigate animal browsing.

Safe stopping areas designed by NCTIR and traditionally planted by Red Tree have a significant aesthetic value as well as hold space for the local community and visitors to stop safely and view the magnificent landscape. These high profile areas work to integrate the roadway into the natural environment and greatly enhance the ecological value of the coastline.

Red Tree’s involvement in the recovery efforts has begun to restore the diverse ecology of the Kaikōura coastline, creating a habitat for local wildlife and enhancing the wellbeing of the land; holding value for future generations to enjoy.