Townsville Water has transformed its water restrictions strategy in a bid to achieve water security while relying on a shallow dam.
An outline and analysis of this transformation formed the basis of Townsville Water Water Operations Manager Mark Harvey's award winning best paper and presentation – Water Security in the Dry Tropics – at the recent Australian Water Association North Queensland regional conference.
“I went through and explained the very high evaporation rates we have in Ross Dam – which is our major water supply – and that evaporation rate drives everything we do,” Harvey said.
“Certainly that opened a few eyes.”
Townsville has recently moved to level-three water restrictions. Under the old strategy, level three was triggered once the Ross River Dam dropped to 5% and water would then have been pumped from the Burdekin.
“This, however, relied on being able to pump sufficient water to maintain the water level for a prolonged period,” Harvey said.
Under the new strategy, introduced in August last year, level three kicked in when the dam dropped to 20% earlier this month.
“The new regime significantly lifts the restriction and pumping trigger points due to the uncertainty of being able to stop the descent of the dam level even once the pumps are running,” said Harvey.
Harvey said given weather patterns and evaporation rates, it was extremely important for the city to think of water security in a holistic way.
“Water security is often thought simplistically as 'just build a piece of infrastructure and you'll be right' so I went through all the different aspects that make up water security for us – buying water allocations and having a restriction plan – and how we had to incorporate them to work out our future strategy,” he said.
“It's also important to realise just how significant the rainfall patterns are for a city in the dry tropics – if we miss a wet season we get very little rainfall for the year.”
by Water Source
