By Daniel Collins
‘Water. It turns the turbines that power our country, and it irrigates the fields that power our economy.’
With that, John Watt introduced an episode of ‘Ever Wondered?’ about water. Three NIWA scientists, myself included, were among those who featured in the half-hour show.
The thrust of the episode was to examine how much water we have in New Zealand, how this might change in the future, and how we can help balance demand and supply. Waiology has broadly answered the first question here and here.
Looking to the future, we have to turn to models. Models are a synthesis of how we think reality works, and if the models do a good job at describing the present, we can use them to describe plausible future conditions. With several such models it has become apparent that drought prone parts of NZ are likely to become more so, particularly Canterbury where farmers would become ever more reliant on irrigation.
But models are powerless without data, and so we must continue to measure how much water there is, and why it’s there. The combination of better data and better models in turn allows decision-makers — be they policy makers or farmers — to make more informed judgments. Resource managers would have a better idea on how much water can be allocated from a river or aquifer without compromising other water needs. Farmers would have a better idea on how much to irrigate.
One innovative approach to increase irrigation efficiency highlighted in the show is offered by a couple of agricultural engineers from Precision Irrigation. They devised a system where they make a map of the soil properties of a field using an electromagnetic sensor, and then configure the individual nozzles of a sprinkler to turn on or off so that just the right amount of water falls to the ground.
Of course, I’m only giving you a synopsis of the episode here. I do recommend you view it in full, though the show is itself a synopsis of what we know and how we’re trying to solve the freshwater management problem.