this is a preposition, not to-infinitive
how we know the differences between to as stand as preposition and to as infinitive?
because I ever see the using of prior with to, so I do the same
Here the dictionary said
prior to sthbefore a particular time or even
example : the weeks prior to her death
be more specific in here - however, it does not mean that you need to write many miniature details
why only sea water? how about the water in the reservoirs?.... do not make mistakes in the body paras
as I observed, the diagram shows evaporation is only comes from sea water and the reservoir function is to collect rain water :((