Sea-draining catchments

This layer was extracted from FENZ.

The FENZ database grew initially out of work initiated under a whole of government initiative
run under the Sustainable Development Programme of Action for Freshwater to identify Waters
of National Importance (WONI) for tourism, irrigation, energy generation, industrial uses,
recreation, natural heritage and cultural heritage. The Department of Conservation (DOC) was
given the task of identifying a candidate list of nationally important aquatic systems for freshwater
natural heritage. Following the production of satisfactory results from an initial pilot analysis
(Chadderton et al. 2004), the Department commissioned a range of further research (mostly from
the National Institute of Water and Atmospheric Research and Landcare Research), to better
identify sites with high natural values, with separate projects focussing on lakes, wetlands, and
rivers and streams. These sought in particular to develop improved descriptions of biological
values, more comprehensive ecosystem classifications, more robust assessments of human
impacts, and higher resolution methods for the ranking of sites. This DVD presents many of the
data resources and results produced during that research, along with additional relevant data
produced for the Department during research on freshwater biodiversity patterns funded under
the Terrestrial and Freshwater Biodiversity Information System fund (TFBIS).

Our description of the spatial locations of rivers and streams was drawn directly from the existing
River Environment Classification (REC — Snelder & Biggs 2002), i.e., the majority of our riverine spatial data are delivered using the REC network topology, although with substantial numbers of
REC flow-lines in lakes removed by overlay against the lake spatial data. We highlight in particular that the REC topology was derived by automatic analysis of digital elevation data based on
national 20m contour data, rather than from the topographic map stream lines. While use of this
relatively coarse resolution elevation data generally provided good identification of stream flow
lines in hill-country, it is less satisfactory at detecting smaller streams in flatter areas, e.g., alluvial
flood plains. Users should therefore be wary of over-relying on the positions of small streams in
these low-gradient landscapes, using the spatial data with a degree of caution, backed by field
knowledge where required.