access issues:
not being able to get to your destination due to persistent flooding of roads, severe road damage from flood waters, tree falls or landslides (the latter two may well be delayed after the flood)
not being able to extricate yourself from the region due to the above
camp grounds may be closed - these are often on low lying areas near rivers and amongst the first to be flooded and camp grounds may remain closed for months after a flood event
hiking paths are often closed and inaccessible due to fallen trees, flooded paths, damaged bridges, land slides, etc.
getting bogged in the very soft water-sodden soils, especially if previous 4WD owners have created very deep ruts - NOT a great time for those with caravans!
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trying to drive across a flooded stream is extremely dangerous - doesn't take much water to make your vehicle float and be carried down stream to eventually sink in deeper waters
driving along a flooded road can be dangerous - even bitumen roads can be severely undermined and the road shredded by flood waters leaving hidden submerged very deep holes, rutts or loss of road which may lead to the car rolling over and floating downstream
getting stranded on a road in a flooded flood plain can be dangerous as rising waters may cause your car to float off the road and become fully submerged in a flooded deep roadside channel
trying to walk or swim in flood waters is a major risk of being caught in submerged debris or being swept away by strong currents
increased numbers of grumpy snakes as they try to find high ground and new homes
much increased numbers of mosquitoes and their infective risks
increased risks of trees falling on your vehicle or your tent
increased risks of land slides falling onto your tent or
additional risk of no access to:
potable water - flood waters are NOT potable and would require much filtration and decontamination to make it any where near safe to drink - and chemical toxins may still be a hazard
electricity, mobile phone access and internet access to the region may be cut, especially if a wind storm has knocked down infrastructure
food and supplies - local stores may have been evacuated during the flood or have been flood damaged and are thus closed
dry fire wood
suitable accessible ground to set up a tent that is not flooded (especially if you are on a wide flat flood plain) or at risk of flooding
if there is ongoing rain or high humidity then hypothermia may be an additional risk as it becomes harder to keep warm and dry
increased risk of injury and skin infections
things tend to be more slippery creating falls risk
water sodden gear becomes heavier and creates a higher risk of back strain injuries
walking in flooded areas is dangerous - there may be submerged deep potholes even in bitumen roads, and submerged sharp objects may cause injury which are then prone to infection
vehicle damage risk is higher
the struggling, exhausted locals may not be appreciative of your presence unless you are clearly going to be there to help them or inject money into their community