Freshwater and Estuaries research projects

Plastic pollution processes in rivers

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.

NZ Water Model - Hydrology

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.

New Zealand fish passage guidelines

The New Zealand Fish Passage Guidelines sets out recommended practice for the design of instream infrastructure to provide for fish passage.

The New Zealand Estuary Trophic Index

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.

National riparian restoration database project

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.

Modelling vegetation-impacted morphodynamics in braided rivers

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

Managing water allocation on the West Coast

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.

Geomorphology influences periphyton abundance

This research project investigated whether the mechanisms for periphyton removal in rivers relate more directly to hydraulic and geomorphic conditions than flow metrics.

Mercury biomagnification in three geothermally-influenced lakes differing in chemistry and algal biomass

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.

Flow requirements for galaxiid fish spawning

Many of our iconic native fish species, such as whitebait and eels, rely on river flows to cue key life-cycle stages, including migration and reproduction. As pressures on water resources increase, the risk of disrupting these flow cues, and therefore impacting fish populations, becomes greater.

Understanding fish passage in New Zealand

NIWA scientists have been investigating the different capabilities of our native freshwater fish species in order to help design effective solutions for overcoming barriers to migration

Recovering plants for reintroduction to Lake Ōmāpere

NIWA recently hosted visitors from Northland to view cultivated plants from Lake Ōmāpere that are now ‘extinct in the wild’, and discussed plans for their reintroduction to the lake in the future.

Waitaki weed surveillance plan

NIWA and Meridian are developing a management strategy on LINZ crown owned lakes for pest aquatic plants – weeds, the alga Didymosphenia geminata (Didymo) and filamentous green algae (both native and introduced) - in the Waitaki Catchment.

Biofilms in groundwater systems

Biofilms – communities of microorganisms growing together – are common in groundwater systems, but we don't know much about them. Our scientists devised a series of studies to start to understand what environmental changes they can cope with and still play their role in a healthy groundwater ecosystem.