Science Centres: Freshwater

Using the NRWQN

State of the Environment (SoE) Reporting

The NRWQN is one of the cornerstones of the Ministry for the Environment’s (MfE) fresh water reporting programme. Data collected by the network has been used by the Ministry in two national State of the Environment (SoE) reports for New Zealand (in 1997 and 2007) and several regional councils have also incorporated NRWQN data into their regional SoE reporting.

A report on two decades of national water quality trends was produced for MfE using NRWQN data.  The analysis showed that nutrient concentrations have increased over the past 2 decades due to the expansion and intensification of pastoral agriculture.  Also land use change is encroaching on baseline sites. 

Examples of flow-adjusted total nitrogen concentration time series from 1989 to 2007 are given in the figures below.  On the right(sampling site CH4 on the Waimakariri River, near Christchurch) total nitrogen concentrations increased after about 2004, while on the left (Manawatu River near Palmerston North) concentrations decreased in the same time period.

Total Nitrogen on the Manawatu at Teachers College

Total Nitrogen on the Waimakariri (above old highway bridge) near Christchurch

A report on trends in periphyton cover in the NRWQN is also available on the MfE’s website. This report showed that periphyton cover was high enough to impact on river recreation and aesthetic values, and that human activities, including pastoral agriculture, have increased the occurrence of nuisance periphyton in the NRWQN rivers.

Water resource management

NRWQN data are also used by NIWA and other environmental research and consulting agencies, for addressing practical problems of river water quality management. 

Regional Councils (who manage water resources and other natural resources in New Zealand at the regional level) are the largest category of users of the NRWQN, closely followed by environmental consulting firms.

International reporting

The NRWQN contributes to meeting NZ’s international environmental reporting obligations. Data from the NRWQN is provided to the World Health Organisation’s Global Environmental Monitoring System (GEMS) programme. NRWQN data has also been used for five-yearly reporting to OECD on the state of NZ’s environment.

Scientific research

The NRWQN has helped to advance scientific understanding of New Zealand river ecosystems, often with applications to rivers globally.  For example, the NRWQN has been used to calibrate national-scale models of the delivery to the sea of materials from the New Zealand landmass. Scott et al. (2006) estimated that New Zealand’s rivers exported the equivalent of 40% of New Zealand’s fossil fuel emissions.  Elliott et al. (2005) used the SPARROW catchment to predict the mean annual loads of nitrogen and phosphorus delivered to New Zealand’s coast.  Scarsbrook et al (2003) demonstrated that climatic effects, in this case the El Nino Southern Oscillation, had an influence on water quality.

Access to data

NRWQN data is available free to registered subscribers online via the Water Quality Information System (WQIS) at http://wqis.niwa.co.nz.WQIS also gives useful background information on the NRWQN, including ‘metadata’ on each of the 77 river sites.Numerous scientific publications have also been generated from the outputs of the NRWQN.