I would suggest a network of canals and reservoirs all across our country. The reservoirs can be away from cities in central Queensland/NSW/NT/WA regions. Our coastal area gets too much rainfall /cyclones etc and central Australia is dry. So whenever too much rainfall is in one area, water can be discharged into canals to take the water to any of the reservoirs and the water can be used later on for farming or other purposes.
So our rivers don’t run dry half the time. The houses in flood prone areas should be properly designed (floating). Alternatively, all houses should be built on high lands (i.e. designed to withstand cyclones(cat 5) or floods in coastal areas).