Key points: Bitterns are what is left when most of the water and salt (NaCl) is removed from seawater through evaporation. K+S is proposing pre-diluting bitterns with seawater and returningRead more
Ashburton Salt project impact on Exmouth Gulf little to none
Ashburton Salt project
Impact on Exmouth Gulf nutrient inputs little to none.
- The Ashburton Salt project proposes a series of salt-water ponds to be located on existing salt flats.
- These salt flats form part of a wider wetland ecosystem, supporting algal mats and mangroves which underpin productivity of Exmouth Gulf.
- Extensive research conducted and peer reviewed by experts studied the movement of nutrient and surface-water flow to measure potential impacts of the Ashburton Salt project on the wider ecosystem.
- Modelling indicates that the proposed project will not significantly alter nutrient exports or pathways due to the small scale of predicted reductions and infrequent nature of rainfall in the area.
- The experts found impacts related to nutrient pathways would be so small, the overall impact on the Exmouth Gulf would be “little to none”.
Impacts to nutrient pathways, as a result of the proposed Ashburton Salt project, will not be great enough to impact the Exmouth Gulf, new research has found.
The research into nutrient pathways was conducted by Water Technology and peer-reviewed by DHI Water & Environment, an EPA-approved third-party expert, as part of the Ashburton Salt project.
It is excellent news according to K+S Salt Australia Managing Director Gerrit Gödecke.
“While nutrient flows may not be as exciting as whales or dugongs, it is possibly the area most important to research properly and get right,” Mr Gödecke said.
“Even though salt flats may seem dry and lifeless, they form part of a wider wetland ecosystem, which supports algal mats and mangroves and underpins productivity of nearby waters.
“Put simply, nutrients are ‘food for the ecosystem’ so we needed to get the science right to address potential environmental impacts.
“By doing this, we have planned the project in a way that reduces impacts of changed nutrient flow to next to nothing – which is exactly the way it should be.”
Nitrogen and nutrients – feeding the Exmouth Gulf.
The solar salt project, which comprises predominantly a series of large saltwater lakes is proposed to be located on existing salt flats south of Onslow.
This region is known to play a critical role in the marine ecosystem of nearby waters, and also the Exmouth Gulf, by providing nutrients that “feed” nearby marine life when flushed into the ocean.
In essence, nutrients – in particular Nitrogen – are the beginning of the food chain for the Exmouth Gulf and feed it through two sources:
Ocean upwelling is the process by which deep, cold, nutrient-rich water rises toward the surface (known as “Ekman transport”). Ebb and flood of tides, providing water from offshore sources and removing water from nearshore sources, has a “mixing effect” combining nutrients from offshore sources into nearshore water.
- Upwelling and eddies deliver large intermittent pulses of nutrients.
- Tidal exchange delivers small daily loads of nutrients.
Tidal creeks, mangrove habitats in the intertidal zone, algal mats and salt flats beyond the tidal limit of the mangrove zone all provide a nutrient source for creek and nearshore waters during regular tidal inundation.
The Project terrestrial rainfall catchment area also provides a source of nutrients to nearshore waters after overland flows and rainfall run-off, particularly after extreme rainfall events. After major rainfall events, nutrient rich overland flows reach coastal waters, including the Exmouth Gulf.