Neighborhoods and communities hit by hurricane Harvey can use the National SOS Radio Network to organize in the aftermath.
Use commonplace FRS/GMRS walkie-talkies to communicate with others in your neighborhood. If you have power, listen to Channel 1 for possible distress calls. With radio, it’s possible to make contact with nearby neighborhoods and towns unreachable for flooding or damaged roads.
If possible, make contact with your nearest amateur radio operator who can relay a message or possibly communicate directly with emergency response agencies in your location.