I am a country boy, but I have spent some time living in a couple different big cities. I have never faced a disaster while I was there, but I did try to plan for what-if situations that might hit while I lived there.
Urban survival has the same priorities as rural survival, namely a secure shelter, a source of potable water, a source of food and a way to keep others from taking it from you.
Avoid Trouble / Keep a Low Profile
The best way to survive in an urban environment is to keep a low profile, by not drawing attention to your preps. If everyone on the block, condo association, apartment complex knows you are a prepper, then there is a good chance that someone’s no good brother-in-law will know about it and show up trying to kick down your door for your supplies.
You only need to have one person say “I know where I am going in a disaster…your house” to teach you how to keep your mouth shut.
Water will be your biggest challenge in an urban disaster. There is a good chance your municipal supply will be cut and everyone will be looking for potable water. You should have a water filter so you can filter any questionable water source. You will also want to try to collect any rain that falls.
Even if you have plenty stored away you should take advantage of any relief supplies offered by FEMA. This will keep others from wondering why you have water (Remember low profile).
Experts tell us to plan on using one gallon per person per day.
Guerilla Food Sources
If you have been prepping you probably have food put away. Like water you should take advantage of any relief efforts and save your supplies in case things get really bad.
Urbanites should try to grow some of there own food regardless. I know of people who have gardened by cutting out a patch of weeds from a vacant lot.
When I lived in Denver my apartment backed up to a golf course. I could of feasted on goose every night. A heavy throwing stick could have quietly supplied a vast quantity of meat every night.
Urban or country the basics of survival are the same; Set your priorities and take care of the important things first.