Chinese coal miner Shenhua has failed to do its homework on the effects of groundwater drawdown at the proposed Watermark mine, according to a researcher from University of Western Sydney.
With conditional approval for coal mining in the Liverpool Plains granted by the Federal Government, researcher Dr Sebastian Pfautsch has suggested that Shenhua needs to rewrite their environmental impact statement (EIS).
A recent study conducted by Pfautsch has showed that trees within several kilometres of an open cut mine in the Pilbara were affected by a drop in the water table, an outcome that could take shape in the Liverpool Plains.
Pfautsch explained the effects of water drawdown, describing a “cone of depression” being formed.
"I always refer to an example where you have a very thick liquid in a bowl and you pop a straw in the centre of that bowl, and you start sucking that out, sucking liquid out," he said.
"It would form what we call a cone of depression towards the centre where your straw is.
"Now, depending on the rate of pumping, the cone of depression will be deeper or more shallow."
Pfautsch said the depth of mine, among other factors, has an effect on the diameter of the cone can spread across the landscape.
In terms of Shenhua’s EIS, Pfautsch said studies of the effects on groundwater and mitigation of effects was limited to the boundaries of the mine site, failing to take into account endangered box gum woodland near the mine.
"Now if you look at a map of where these several mine pits within the larger boundary of the mine, where they actually propose, you will see that towards the west, the mine area is abutting straight away onto the Breeza State Forest,” he said.
"I would expect, if you want to prevent any effect of your dewatering happening in or affecting that forest with its endangered woodland, that you start monitoring in this area as well, and not just on your mine site."
Despite Pfautsch’s specific focus on trees, he also said there could also be an effect on farms near the mine.
"You would expect that there is an impact if you have started digging a very big hole and you dewater the area around it that you will feel an impact further — either upstream in the aquifer or downstream."
"From my reading, there could be more to actually prevent the chance that the environment will be harmed by dewatering."