To put just the Ord River into perspective. Prior to daming the Ord used to discharge 2,500 gigalitres into the ocean each day during the wet season. 1 gigalitre is 1,000 megalitres...which equals 1,000 Olympic pools...2.5million pools per day to the ocean. Perth uses about 250 gigalitres per year. So 10yrs of water (in today's usage) was wasted prior to daming. Most has been captured.
Put all the worlds water resources together and the world definitely hasn't a shortage for the population let alone for irrigation.
If we worked our way through each resource there would be similar results to water.
