I assume your ! means that you think this has been forgotten in...

I assume your ! means that you think this has been forgotten in the entire design of the operation.
I am sure evaporation rates were modeled when designing the pond system and processing capacity. They certainly don't need to be modeled every year or so as the climate data being captured on a daily basis will no doubt be added into the phase 2 pond design.
The initial design would have been based around mean/median evaporation on a month by month basis to deliver the projected output. To build for the worst 10% of possibilities would be very expensive and not needed in most years. The plan to add dryers/crystalizers is sensible, can be paid for out of cash flow and will be done in light of on the ground knowledge rather than projections.