River Environment Classification
NIWA has developed a GIS-based environmental classification of New Zealand’s rivers. The development of the River Environment Classification (REC) was supported by the Ministry of the Environment (MfE) with the involvement of a number of regional councils.
The REC is an ecosystem-based spatial framework for river management purposes and provides a context for inventories of river resources, and a spatial framework for effects assessment, policy development, developing monitoring programmes and interpretation of monitoring data and state-of-environment reporting.
The REC has been used to classify all the rivers of New Zealand at a 1:50,000 mapping scale. The area classified comprises 267,000 km2 and 426,000 km of river network.
The REC introduces two major differences to other landscape classifications or ‘regionalisations’.
- The REC is a multi-scale classification, delineating patterns at a range of scales from approximately 104 km2 to 1 km2.
- The REC is based on a network of ‘sections’ that are associated with their upstream catchments. The mapped classification appears as a linear mosaic showing longitudinal spatial patterns that are typical of patterns of many properties of river ecosystems.
The REC has now been updated to include data derived from the latest Land Cover Database (LCDB2). The data needed to update the REC shape files and a report explaining the new land cover classes and how to update the REC is included in this downloadable file.
REC subcatchments have now been aggregated to form larger subcatchments. The sizes are determined by stream order. Eight shape file layers comprising subcatchments of order 1 to 8, plus instructions, are included in this downloadable file.
A proportion of REC network sections have now been associated with river and stream names. A file and instructions on how this can be used to update your REC are included in this downloadable file.
User Guide and Example
MfE has published a detailed user guide for the REC which is available here as a PDF file. The guide covers the conceptual basis for the REC, the use of the REC and associated tools in a GIS and case studies showing the use of the REC as a spatial framework for broad-scale environmental assessments.
An example of a river classification as a GIS layer in ARCView format is also available. (Freeware ARC viewer is available from www.esri.com
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For an example the use of the REC for interpreting and reporting environmental data see “Water quality in low-elevation streams and rivers of New Zealand: recent state and trends in contrasting land-cover classes” in NZ Journal of Marine and Freshwater Research.
FAQ and Reference
Read more about the REC and its application in:
Snelder, T. H., F. Cattaneo, A. M. Suren and B. J. F. Biggs. 2004. Is the river environment classification an improved landscape-scale classification of rivers? Journal of the North American Benthological Society. 23(3):580-598.
Snelder, T. H., R. Woods and B. J. F. Biggs. 2005. Improved eco-hydrological classification of rivers. River Research and Applications 21(6):609-628.
Snelder, T.H.; Biggs, B.J.F. (2002). Multi-scale river environment classification for water resources management. Journal of the American Water Resources Association 38(5): 1225–1240.
Snelder, T.H.; Weatherhead, M.; Biggs, B.J.F. (2004). Nutrient concentration criteria and characterization of patterns in trophic state for rivers in heterogeneous landscapes. Journal of the American Water Resources Association 40(1): 1–13.
Snelder, T. H., and K. F. D. Hughey. 2005. On the use of an ecological classification to improve water resource planning in New Zealand. Environmental Management 36:741–756
Contact
For further information or to ask questions about the REC email j.leathwick@niwa.co.nz or by post to NIWA, PO Box 11115, Hamilton.