The REC groups rivers and parts of river networks that share similar ecological characteristics, including physical and biological. Rivers that share the same class can be treated as similar to one another and different to rivers in other classes. The REC classification system groups rivers according to several environmental factors that strongly influence or cause the rivers’ physical and ecological characteristics (climate, topography, geology and land cover). A catchment is a polygon that defines the upstream watershed of a river system or sub-system. Land cover within the catchment was used to populate the river classification factors (see table 1.1 of the User Guide https://data.mfe.govt.nz/document/123-rec-user-guide-2010/ ).
Additional metadata can be found at http://www.mfe.govt.nz/publications/ser/metadata/env-class/page19.html
