Setting priorities for protecting rivers and streams

Information stored in the River Environments Classification (REC) database has been used to help set priorities for protecting and restoring river and streams.

The REC describes both the conditions at each New Zealand river segment (river flow, temperature, shading from riparian vegetation, distance from the coast) and the nature of its upstream catchment (upstream elevation, slope, land use, rock type). This information has been used to classify all of New Zealand’s rivers and streams into groups that have similar characteristics, such as low-gradient lowland rivers and streams, lowland hill-country streams, mid-elevation rivers and streams, rivers with strong glacial influence, montane rivers and streams, etc. Using this classification, we can systematically identify not only those types of rivers and streams that are not well represented in existing reserves, but also where the best examples of those habitats can be found.

Building on this, we use selection software that identifies optimal sets of sites for protection. This software takes account of the river and stream habitats occurring in each catchment, along with information about the likely condition of each river segment and its upstream catchment. Using this approach, we can quickly identify a set of catchments or subcatchments that would maximise biodiversity protection, taking into account the network nature of river systems (software selects interconnected sub-catchments), the effects of human impacts, and favouring those river and stream segments that would provide maximum value in extending currently protected areas. For more details see this Water and Atmosphere article.