What went wrong....

I think there's one key problem the show had: tonal dissonance.

Reading the threads here, there seemed to be two types of people watching the show. The first were wanting something serious, realistic, and gritty. "The Walking Dead", but replacing zombies with assorted natural disasters. These people tended to watch, and then either quickly tune out (and let everyone know), or else keep watching "in hopes it'd get better" (and let everyone know they didn't think it did).

The second group grokked real quick that this was a "so bad it's fun" show, and they were in for a treat... for about the first half the season. Around the volcano episodes though, the show tried to take itself seriously and grow up a bit. Gone were "Booty and Ass-wang", gone were the hentai kudzu monsters, gone were teenage girls willing to kill each other over a working cellphone, gone were characters like post-apocalyptic-Wayne-Brady and utterly-useless-nurse. In short, all the crazy gonzo fun stuff kind of came to a screeching halt as the show tried to wrap up its plotline. And yes, it did have a plot (even those stupid punch cards were kinda-sorta made relevant).

I think future SyFy shows could take a lesson (or three) from Z Nation, and acknowledge that half your target audience will -hate- your show (and of them, half will actually stop watching). But the other half... if you can just embrace the goofiness and camp and fun, you can build a loyal fanbase with them.