HBRC has proudly spent $4.7 million on detailed aerial mapping (via electromagnetic technology) of the Heretaunga and Ruataniwha aquifers (and other locations) conducted in early 2020.
But the data acquired still can’t answer critical questions about aquifer water supply and availability.
At a recent presentation to HBRC Councillors, staff and GNS Science expert Zara Rawlinson gave a technically complex explanation of the data that has been collected.
But as the first Councillor to ask a question remarked: “I got everything up to the point when you said, “Hello, I’m Zara”! Murmurs of agreement.
The burning questions at HBRC and amongst water users for at least a contentious decade now has been … How much water is in our aquifers? Are we depleting them faster than they recharge? Or is there even more water at greater depths that could still be safely tapped?
Another councillor asked precisely that question.
The GNS expert commented: “We haven’t run scenarios related to water management.” And, “We would need additional drill holes at greater depth.”
Old-fashioned bore holes! To validate any further interpretation or modelling.
Those with resilient memories will recall that ten years ago the region’s two main well drillers were lobbying hard for HBRC to sponsor a 2-3 critical deep bores to help answer these questions. But given the expense (about $1000/metre, or about $3m for three 300 metre bores), Council and its science team opted for a high-tech 3D aerial mapping approach. This has cost $4.7 million, including $2.4m from HBRC, $2.1m from the Provincial Growth Fund (whose principal interest was water security) and $300,000 in-kind from GNS Science.
Now, after capturing data across 8000-line kilometres of flightlines to an average depth of 300 metres, and as the TANK plan for the Heretaunga aquifer twists in the wind, we still don’t know if we have more water to allocate.
Moreover, staff conceded the data wasn’t of value to another big science project just completed, which raised the prospect that different management of the Ngaruroro River stretch thought to replenish the Heretaunga aquifer might increase natural recharge.
Not that the data isn’t valuable. Apparently it will assist understanding of how and where water flows through the aquifer. So that, for example, were the buried waste dump at Roy’s Hill to spring a leak, we’d have a better idea of where the toxins went. And therefore helpful for charting the ‘source protection zones’ around our municipal drinking water wells.
But to be useful for the huge water supply/allocation decisions HBRC must make, new groundwater models for the two aquifers using the new data still need to be built, a process HBRC’s staff says would take 2-3 years. So we’re back where we were 10 years ago … and apparently still need deeper million-dollar bore holes to solve the riddle authoritatively.
As a former councillor, I was quite disappointed by what I heard. Councillors seemed a bit perplexed and called for a workshop to drill more deeply into these issues.
That’s a workshop anyone with a commercial, municipal or environmental interest in our aquifers might want to observe. I hope the well drillers are invited.
This is another example of HBRC not knowing what they are doing, and not listening to the experts in the field. Very good at wasting ratepayers money.