Firstly we're a representative democracy. Meaning we elect people to handle the day to day business of running the government, because it's fundamentally impossible for millions of people to vote on every little thing, or even every big things. That is the express consent given by the people. Don't like it? Vote the idiots out of office. Run for office yourself. Work to get the idiots out of office. You have options, you just aren't using them.
Secondly, you're talking about holding a vote to implement disaster aid in the middle of said disaster. When streets and businesses are closed, and there's no public transportation, and half the county is sick and dying?"
Tell me, who's going to run the polls, let alone monitor them in that situation? Who's going to count them when there's no one able to count? This is why we have a government in the first place. There are some things that simply cannot be held for a popular vote (civil rights is a big one. Gay rights too. Neither of those thing should be voted on by the people, but protected by the courts instead. Because you can't trust the general populace not to vote against taking away the rights of the minority.)
Thirdly California already requires a crap ton of things to be voted on by the people that every other state leaves up to the legislatures.
Biggest problem with Katrina was the lack of a response at first. It was literally ignored for the first few days. That was precious time lost, and precious lives lost. I'd rather the government act, than not at all.