> if all the water left, it could be dry like a desert too This is just a contextual interpretation thing. It's clear that's not what he means because he says

> if all the water left, it could be dry like a desert too This is just a contextual interpretation thing. It's clear that's not what he means because he says it's muddy, so it must be the other thing. Also, it becoming a desert is more extreme, so in that case the writer would probably offer up a more detailed explanation.