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Drought

What

As Canterbury’s climate warms, the likelihood of drought is expected to increase and areas that are already dry, such as the Mackenzie country, will get even drier.

Drought sets in when moisture leaves the soil, through evaporation or plant uptake, faster than it’s replenished. The amount of moisture in soil affects how fast and well plants grow. This includes everything from our backyards and playing fields to farmland and crops.

Historically, Canterbury/Waitaha has experienced about 200-250 dry days per year. We can see the effect of this in the golden hues of our landscape.

The drying of our region over the next century is expected to be gradual, with some districts more affected than others.

Our rural areas that sit at the foot of the Southern Alps, from Twizel through to Hanmer Springs, are likely to become some of the country’s drought hotspots.

Areas along our coasts and Plains will experience increased drought conditions but to a lesser degree than our high country areas.

Impacts

Drought caused by longer periods of dry weather means less water to go around, with restrictions to supply becoming more common. That means there’s less for non-essential water use such as gardening or filling the paddling pool.

Long, dry periods place increased demands on agricultural irrigation to support plant growth. If water supply is limited, production will be affected, and prices of fruit, vegetables, meat and dairy products will likely increase. Warmer conditions can also make it harder to grow crops such as potatoes that prefer cooler growing conditions.

Impacts from droughts can ripple through districts affecting the environment, the health of a community and the economy. Areas that rely on rainwater for drinking and other uses like pasture growth can be especially hard hit.

Drought significantly affects our water race network, which is thousands of kilometres long and supplied by rainfall, snowmelt, rivers, and springs. Some of our community’s rely on this network for irrigation, supplying water to stock animals and for fighting fires.

The availability and efficiency of irrigation water is critical for determining the type of land use, including where certain crops or pasture can be grown, especially as the effects of drought and limited availability of water become more apparent. Less efficient irrigation can affect production and drive up the price of produce for us all.

Drought can deplete the water we have in storage, which means both urban and rural communities that rely on water storage from rainfall or streams/rivers, or that have high water use, may experience water restrictions. We have seen this recently in Banks Peninsula, where rainfall dropped to its lowest level in a decade, putting extra pressure on the water supply for communities there.

Long-term drought affects the availability and quality of our drinking water as reduced stream and river flows can increase the concentration of pollutants in the water. Viruses and bacteria can also pollute both groundwater and surface water when rainfall decreases, and people who get their drinking water from their own wells may be more vulnerable to drought-related infectious diseases.

Wastewater can become more concentrated if there is less water in our pipes to dilute it, posing a threat to human health and ecosystems when it is discharged. Resolving this will require greater investment in wastewater treatment in the years to come.

Drought can significantly impact our native flora and fauna. Long dry periods can cause native trees to die and be replaced by more drought tolerant introduced species, increasing the risk of wildfires. This directly reduces the food resources of species that are reliant on our native ecosystems to survive, putting the richness of our biodiversity at risk.

Increasing drought, and its impact on landscapes and biodiversity, poses a significant risk to Māori interests, values, practices and wellbeing. These impacts include a loss of mahinga kai, taonga species, access to culturally important plants, and changes to geographical features that are integral to tūrangawaewae.

Taonga species are at risk from a range of climate change threats such as drought, flooding, and sea level rise, with flow-on impacts to the availability of food and mahinga kai. Seeking out new opportunities for abundant food supply is already being identified as a high priority by iwi.