Poor flow in BOP waterways despite rain

File Image/SunLive.


Despite last weekend's rain, parts of the Rotorua and Tauranga region are still experiencing low flows in some streams, according to Bay of Plenty Regional Council.

Flows in the Paraiti (Mangorewa) River and the Ngongotaha Stream have steadily been dropping since the summer of 2017/2018.

Both have been flowing at their lowest rates for this time of year in over 30 years.

Lower than normal rainfall in parts of the Bay of Plenty has resulted in these lower stream flows and declining groundwater levels and, unfortunately, weather forecasts for the coming months are indicating warmer than normal conditions.

Water Shortage event manager Steve Pickles says the warmer weather conditions could mean an even more challenging spring and summer for our local waterways for 2021/2022.

“Parts of the region are in long term rainfall deficit,” Steve explains. 

“While small rain events and the cooler winter months provide some respite, it’s not solving the underlying lack of rain over the longer-term. 

“If we don’t get enough rainfall this winter, our aquifers, streams and rivers won’t have a chance to recharge themselves before we head into another summer.

“Low stream flows can adversely affect stream health. If a stream dries up or heats up too much, it becomes a less desirable habitat for aquatic species and also affects the cultural and amenity values of the stream.

“Water users will also struggle to pump water through their infrastructure,” he says.

Average river flow over a seven day period for the Ngongataha Stream (blue) and Paraiti Stream at Mangorewa confluence (green). Photo. BOPRC.

Steve says as our climate continues to change, NIWA were predicting more extended periods of warmer days for Bay of Plenty, interspersed with periods of intense rainfall. 

“As a result, we’re likely to experience drought conditions more frequently, which will have implications for pasture, crop and animal health.”

For more information on Bay of Plenty Regional Councils dry weather management please head to boprc.govt.nz/dry-weather .

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