We have called the project CAREX, which is an acronym for the Canterbury Waterway Rehabilitation Experiment. Carex (also called pūhio) is also the scientific genus of an important plant used in riparian plantings throughout New Zealand waterways.
Fencing and planting of riparian margins are widely promoted and undertaken to improve water quality throughout Canterbury and New Zealand. Although this is a very important first step, frequently riparian management alone often results in limited improvement in either water quality or waterway health. Our aim is to overcome this problem.
Our previous research indicates that several factors influence the effectiveness of fencing and planting on waterway health. In many cases, the riparian management is not in the right place, or “hotspots” of sediment and nutrient inputs into the waterway remain. Moreover, controlling the source of impacts does not solve the legacy of long-term contaminants which have accumulated in a waterway over decades, nor does it restore key species that have been lost.
Our aim is to trial management tools and strategies that are practical and sustainable using existing resources that are widely available. We have ten waterways across Canterbury (from Rangiora, and Te Waihora/Lake Ellesmere to Hinds) typical of those in need of rehabilitation. The waterways represent gradients of agricultural intensity, extent and/or age of riparian management activities and in-stream water quality and biodiversity.