Freshwater and Estuaries research projects

Read more about our freshwater and estuaries research. 

Constructed wetlands, detention bunds, woodchip denitrification filters and planted riparian buffers are examples of a growing suite of edge-of-field and farm-scale mitigation systems that are being trialled across rural New Zealand to reduce the impact of diffuse pollution on freshwater quality
Eutrophication occurs when nutrients in streams, rivers, lakes and estuaries cause excessive growth of aquatic plants and algae (primary producers).
The Whatawhata Integrated Catchment Management (ICM) Project is the longest continuously monitored before-after-control-impact (BACI) catchment-scale study in New Zealand.
A four-year research programme focused on the co-management and restoration of our freshwater taonga species wraps up this year.
While we know that glaciers are sensitive to changes in their local climate, our understanding of exactly how mountain glaciers will respond to climate change is incomplete.
NIWA has established a network of 11 high elevation meteorological stations aiming to gather information about the amount, extent, seasonal nature and long-term change to snow and ice in alpine regions of New Zealand.
The alp-fed braided rivers of Canterbury are treasured for their landscape, recreational amenities, salmon- and trout-fishing, and unique riverine environments – which provide habitat to a host of endangered birds – but they are under threat from land-use intensification and a growing demand for irrigation water.
Of the more than 70 aquatic plant species naturalised in New Zealand, more than 75% have become problem weeds or have been assessed as having the potential to become future problem weeds. Most of our lakes, rivers and streams are affected by at least one of these species.
Fine sediment is the most pervasive and significant contaminant in New Zealand’s rivers, estuaries, and coastal areas.
Braided rivers are an arena where woody weeds and floods are in constant competition with each other. Braided rivers naturally flood frequently, repeatedly mobilising their bed sediments and shifting their multiple channels.
Most of the plastic in the ocean originates on land, being carried to the estuaries and coasts by rivers. Managing this plastic on land before it reaches the river could be the key to stemming the tide of marine-bound plastics. The aim of this project is to understand the sources and fate of plastic pollution carried by urban rivers using the Kaiwharawhara Stream as a case study.
Currently there are gaps in understanding of user decision making processes and public needs and requirements for river forecasting in New Zealand. This project aims to bridge NIWA river forecasting aspirations and capabilities with both the public and decision makers’ requirements.
Bringing together leading scientific organisations and regional councils, this project develops a sophisticated computer modelling framework that will enable users to accurately predict how much freshwater is available, where it has come from, and how quickly it moves in New Zealand catchments.
The New Zealand Fish Passage Guidelines sets out recommended practice for the design of instream infrastructure to provide for fish passage.
Excessive nutrient input (eutrophication) threatens many New Zealand estuaries causing ecological problems, such as algal blooms and poor physical and chemical conditions for estuarine life.
NIWA is undertaking a five-year nationwide study to find out how different approaches to riparian planting influence water quality improvements and to provide better guidance to the people and groups undertaking stream restoration.

NIWA is developing numerical models for predicting how the morphology of braided rivers responds to flow regulation and invasive exotic woody vegetation.

This project investigated the capabilities and utility of NIWA’s Cumulative Hydrological Effects Simulator (CHES) tool for facilitating discussions and decision making associated with setting and applying water quantity limits in the Grey River catchment on the South Island’s West Coast.
This research project investigated whether the mechanisms for periphyton removal in rivers relate more directly to hydraulic and geomorphic conditions than flow metrics.
This research project aimed to understand the causes behind differences in mercury in trout and other organisms in the Bay of Plenty/Te Arawa lakes—in particular what features of each lake explain why mercury in trout is higher in some lakes than in other lakes.