Record low water levels across Waitaha Canterbury
On 21 March 2024, a “moderate adverse event” was declared in Canterbury, as El Niño conditions and a warming climate made their mark. Conditions are still very dry, with our monitoring showing record low water levels across the region.
“Our monitoring is clear, Canterbury is extremely dry, following months of increased temperatures and average to below average rainfall across the region,” Surface Water Science Manager Elaine Moriarty said.
“Many of our water level monitoring sites are at the lowest they have ever been.”
Hot and dry conditions make for perfect storm
El Niño, a weather pattern that lasts for 9 to 12 months and occurs when the ocean surface temperatures in the Pacific Ocean rise above normal levels, arrived in September 2023, bringing with it more frequent dry westerly winds.
Although El Niño conditions were felt throughout summer, rainfall early in the season helped prepare the region for the dry conditions that were to come in mid to late summer.
In March, nearly half of the sites where we monitor groundwater levels were low or very low, even more so in Mid and South Canterbury. Likewise, the average water flow at many sites has also been low or very low compared to previous years.
Several foothill rivers, mostly in South Canterbury, have experienced some of their lowest river flows on record, in February and March.
Brief rain in mid-April provided temporary relief for the alpine catchments and across Mid and South Canterbury. However, the foothill and coastal areas of North Canterbury experienced little reprieve.
There is currently a water shortage direction in place for Lake Opuha.
March 2023: Lake Opuha levels were looking good
March 2024: Dry conditions at Lake Opuha
More dry days ahead as climate warms
NIWA’s seasonal report for April to June puts expected temperatures at near or above average, while rainfall, soil moisture levels and river flows are all expected to fall below normal as we head into winter.
“All the metrics we monitor our region’s water through, including rainfall, river flows and groundwater, paint the same picture – one of a very dry region,” Elaine said.
Back-to-back dry seasons, with little recharge from rain over winter can lead to very low groundwater levels and spring-fed stream flows; a phenomenon that occurred in 2016 and 2017 when consecutive dry seasons led to very low flows in the Selwyn River/Waikirikiri.
As the climate continues to warm over the next century, there is expected to be a gradual increase in dry days, along with an increased chance of drought. Some catchments will be affected more than others.
For areas that are already dry, such as the Mackenzie Country, the future is looking even drier. Rural areas that sit at the foot of the Southern Alps/Kā Tiritiri o te Moana, from Twizel through to Hanmer Springs, are likely to become some of the country's drought hotspots.
March 2023: A greener looking South Canterbury
March 2024: South Canterbury showing drier conditions
The effect on farming
Many farmers can navigate dry conditions through specific management practices. However, the prolonged nature of this dry spell is having a significant effect on farm businesses. The dry conditions, exacerbated by other financial challenges and economic factors, is making life very tough for many farmers and their families.
The Rural Support Trust provides advice, guidance, and support for those on the land at stressful times such as this.