Africa's 4th largest river floods the desert yearly and it never even reaches the ocean[1]. Rain when it falls in the valley around Las Vegas doesn't soak into the ground but does create massive floods[2]. Frankly is doesn't matter how much rain falls if the temperature is unaffected and continues rising.

[1]https://en.wikipedia.org/wiki/Okavango_River [2]https://www.youtube.com/watch?v=UscvetL9xc0