In brief - Strahler system to replace Riparian Corridor
Objective Setting (RCOS)
The NSW Department of Planning and Infrastructure has announced
that from 1 July 2012, the former RCOS approach to riparian
corridors is to be replaced by the more objective Strahler stream
Traditional disagreement on riparian corridors between
developers and consent authorities
Disputes over the extent of riparian corridors and the
permissible uses within these corridors continue to bedevil
greenfield development projects.
Part of the tension lay in the often arbitrary nature of what
consent authorities have considered to be environmentally
appropriate to protect the integrity of the watercourse on the one
hand, and the often substantial loss of developable land - and the
associated impact on profitability – resulting from the
imposition of riparian corridors on the other hand.
"Stream order hierarchy" approach for determining
In a bid to alleviate some of the problems associated with these
tensions, and in recognition of the often inappropriate scale of
corridors imposed on greenfield development projects, the NSW Department of Planning
and Infrastructure has announced a new approach or methodology
for determining riparian corridors.
In summary, the former Riparian Corridor Objective Setting
(RCOS) approach is to be replaced by the so-called Strahler stream
ordering methodology. This methodology, which is essentially a
"stream order hierarchy", was officially proposed in the
early 1950s by Arthur Newell Strahler, a geoscience professor at
Columbia University in New York City.
According to the Department, the methodology provides a more
objective approach which includes set riparian corridor widths, as
opposed to the more discretionary RCOS regime.
Advantages of Strahler approach to riparian corridors
According the Department, the adoption of the new methodology
and the related reforms are anticipated to:
establish clear and appropriate rules on the width of riparian
provide greater flexibility in urban design by allowing a
broader range of uses in riparian corridors, including detention
basins, cycleways, roads and recreational areas
enable works and activities to be offset along the length of a
provide greater flexibility with watercourse crossing
remove the need for vegetated buffers in addition to a riparian
introduce a streamlined assessment approach so that compliant
proposals can be assessed more quickly
NSW Office of Water to manage new methodology
The new methodology will be managed and implemented by the NSW
Office of Water, to which local councils and developers will need
to refer. It is also anticipated that much of the work associated
with determining the scale and extent of riparian corridors will be
addressed as part of the rezoning process.
The Department of Planning and Infrastructure has announced that
the reforms will apply across the state from 1 July 2012.