Groundwater is the water stored beneath Earth’s surface in aquifers (layers of water-bearing rock or sand). It is used for human and stock drinking water, irrigation, and industry, and also has a role in sustaining some rivers, lakes, and wetlands, especially during low-flow periods. The health of surface-water ecosystems also depends on groundwater....

"The rates of establishment (recruitment) of indigenous tree species vary across New Zealand. Changes in the state of the environment (such as from browsing pests, large-scale weather events, or climate change) may change the rates of recruitment of particular tree species. This in turn may alter forest processes. Repeated surveys of the distribution of...

Particulate matter 10 micrometres or less in diameter (PM10) in the air comprises solid particles and liquid droplets from both natural and human-made sources. PM10 can be emitted from the combustion of fuels, such as wood and coal (eg from home heating and industry), and petrol and diesel (from vehicles). Natural sources of PM10 include sea salt, dust,...

River water quality is valued for many reasons including ecological function and habitat, recreational value, its role in supporting people and industry, and its cultural significance. Nutrients such as nitrogen and phosphorus are essential for plant growth, however too much in rivers can lead to excessive growth of river algae, which can degrade habitat....

Greenhouse gases (GHGS) in the atmosphere absorb heat radiating from Earth, warming the atmosphere. Emissions from human activities increase the concentrations of these gases. Increases in these gases increase ocean acidity and are extremely likely to contribute to increased global temperatures, sea levels, and glacier melt. monitoring GHG concentrations...

Bacteria and parasites like campylobacter, salmonella, and cryptosporidium can contaminate our food and water, leading to serious illness. Campylobacter, salmonella, and cryptosporidium are influenced by temperature and other climate variables, and incidence rates may increase as climate change causes temperatures to rise. Monitoring the incidence rates...

River water quality water is valued for many reasons including ecological function and habitat, recreational value, its role in supporting people and industry, and its cultural significance. Nutrients such as nitrogen and phosphorus are essential for plant growth, however too much in rivers can lead to ‘nuisance’ growths of river algae and aquatic plants,...

"Small amounts of nitrogen are a natural component of healthy rivers. Nitrogen is transferred from land to water and is cycled through different forms, which can have different effects. Moderate concentrations of nitrate can cause weeds and algae to grow too fast. High concentrations of ammoniacal and nitrate nitrogen can be toxic to fish and other...

The ocean storm index estimates the number of days in a year when wind speeds exceed gale and storm force on the Beaufort Scale. In a gale, sea conditions are rough and waves can be over six metres high. In a storm, waves can be over 10 metres high. To put this into context, on land a near gale would make walking difficult, and a storm would cause some...

Winter rainfall trends for 30 representative sites from 1960–2016. Rain is vital for life – it supplies the water we need to drink and to grow our food, keeps our ecosystems healthy, and supplies our electricity. New Zealand’s mountainous terrain and location in the roaring forties mean rainfall varies across the country. Changes in rainfall amount or...

Daily rainfall values for 30 representative sites from 1960–2016. Rain is vital for life – it supplies the water we need to drink and to grow our food, keeps our ecosystems healthy, and supplies our electricity. New Zealand’s mountainous terrain and location in the roaring forties mean rainfall varies across the country. Changes in rainfall amount or...

Influenza is a potentially life-threatening virus that spreads quickly from person to person. It is a significant public health issue in this country, with 10–20 percent of New Zealanders infected every year. While influenza outbreaks can occur all year round, rates peak in winter and spring. This is because the virus can survive longer outside the body...

"Phosphorus is an essential nutrient for plant and animal life. Total phosphorus (TP) includes all concentrations in a sample, whether dissolved, in solid form or bound to sediment in the river. Dissolved reactive phosphorus (DRP) is the portion which is dissolved and can immediately support plant and algae growth. Excess phosphorus in our rivers can...

"Freshwater plant and animal pests can have significant negative impacts on ecosystem health by reducing indigenous biodiversity through predation and competition, and destabilising aquatic habitats. Freshwater plant pests can cause economic losses through blocking water intakes for hydroelectricity generation, impeded drainage or irrigation. In addition,...

Maximum ozone concentration during 8-hour periods. Note: Ozone concentrations are given in micrograms per cubic metre of air, or µg/m3. Source: Auckland Council

Nitrogen dioxide (NO2) is a gas. It can be emitted directly into the air but is most often formed when nitric oxide (NO) emissions react with other chemicals in the air. Nationally, road motor vehicles are the main human-made source of nitrogen oxides (NOx, the collective term for NO2 and NO). NO2 may cause respiratory infections and reduced lung...

Note: PM10 concentrations are given in micrograms per cubic metre of air, or µg/m3. Source: Regional councils of Waikato, Wellington, Canterbury, Otago; Auckland Council

NIWA supplied ozone data in two forms, with different starting dates: - measurements made using a Dobson spectrophotometer (number 72), from 1987 - data assimilated from satellite measurements recalibrated against the global Dobson network, from 1978. NIWA takes measurements using the Dobson spectrophotometer 72 under clear-sky, direct sunlight conditions...

Urban water quality indicators include heavy metals, nutrients, and E.coli. The concentrations of these indicators are compared to the proportion of urban land cover in catchments. Heavy metals have the ability to accumulate in sediments, shellfish, and other aquatic organisms. Metals can reach toxic levels in organisms making them unsafe to consume and...

New Zealand waters have at least 113 species of chondrichthyans (sharks, rays, and other cartilaginous fish species). They are particularly vulnerable to overfishing because they are long-lived, mature slowly, and have a low reproductive rate. Chondrichthyans are important for healthy ocean ecosystems, and reporting their commercial catch and bycatch...