News & Insights

Cardno’s geomorphology experts assist field team on erosion-control projects in New Zealand

A team of American experts in geomorphology, collection of detailed channel-resistance data and stream-restoration design recently travelled to the North Island of New Zealand to assist the Healthy Waters Section of Auckland Council on a couple of erosion-control projects in the Auckland region.

The team included Andrew Simon, Heather Schwar, Gail Simon, and sub-contractor Danny Klimetz.

First, they worked with a local team to conduct measurements of the resistance of local river banks to hydraulic and geotechnical erosion. This work precedes bank-erosion modeling which will be used to guide stream-restoration alternatives and a conceptual restoration design.

The field work also included a series of Rapid Geomorphic Assessments (RGAs) to determine the general stability of the stream corridor and the general types of mitigation measures that will be tested with the model and that would be appropriate for the conditions.

Next, the team spent several days on Kourawhero Stream, providing insight into major erosion hotspots and potential mitigation alternatives of a large stretch of the river. The reach was selected because a previous study by the team identified this reach as producing the bulk of the erosion in the catchment.

The data collected allowed the team to select three sites for the implementation of effective Geomorphic Effective Solutions (GEMS) to stabilize eroding banks and beds. Their assistance included leading a technical advisory group and engaging with the community at an open meeting to inform local property owners of the state of the river.