Hi Hakimi,
Great questions, and it’s fantastic to see you taking into consideration Dawul Wuru’s identified needs in regards to this project, as well as weighing up the benefits and drawbacks to different approaches.
As you’ve mentioned, the Design Brief specifies a low-cost option, and, as you’ve correctly pointed out, a structure that spans the entirety of Dungarra (Redden Island) would be of a significant cost to deploy and maintain.
I would encourage you to think about your design not as an either/or situation, but rather how can you make your design be scalable so that it can be deployed at different lengths. For example, Dawul Wuru have identified that the river banks of the Barron River on Dungarra are of most concern – could you design a solution which would could be deployed in that location for a reasonable cost, but could also be applied at a larger scale around the rest of Dungarra if/when more funding becomes available?
If you haven’t had a look already, the FAQs: Big Tricky Questions document speaks a bit about how to think about budgets and scalability of projects which can help guide your thinking.
I hope this helps, good luck with your project!
Rachel