http://content.time.com/time/nation/article/0,8599,1817603,00.html
Take note of these:
— Don't be deceived by water that looks shallow. Six inches (15 cm) of water will reach the bottom of most cars and can cause stalling and loss of control, according to FEMA. A foot of water will float many cars, and two feet of moving water can carry away most vehicles — including SUVs and pickup trucks. In other words, if you can turn around, do it.

— If floodwaters do rise around your car, leave the car and move to higher ground ...

— ... Unless you don't know the depth of the water or if you are in moving water. In those cases, stay in the car and wait for help.

— If you must walk through water, walk where the water is not moving. Even ankle-high water, if it is moving, can make you fall. Use a stick to check the depth and firmness of the ground in front of you.

— If you do get swept into a fast current, don't fight it, according to the U.S. Army Survival Manual. In fast, shallow water, swim on your back, feet first. Keep your feet up to avoid hitting debris or getting pulled under.