A series of storms hit south central United States during the week of May 24th. Places in Texas saw excess of over 10 inches of rain in less than 24 hours. That easily puts those areas well over the 100 year flood delineation. The Blanco River in the Austin, Texas area went above flood stage by over 30 feet. Bridges crossing the Blanco River became submerged. Needless to say, many lives were lost and some are still missing.
One of the main ideas in hydraulic and hydrologic modeling is the try and model real time flood delineation. Traditionally, HEC-RAS, HEC-HMS models would be run against known parameters to make a floodplain. Some software would take these models and add some real time feeds to try and give real time flood delineation. Traditionally, this would be augmented by stream gauges reporting water elevation. These would feed into the models via XML or RSS.
One pre-social media idea is to have a series of user supplied data via rain gauges. CoCoRahs is a program where users would obtain a physical rain gauge and anytime it rains, an user can add the rain total to the website. Part of using these user supplied data is to act as "ground truthing" what the stream gauges and the radars are reporting.
Now that social media is ubiquitous, this should be another input into real time flood warning systems. Public is much more likely to tweet than to put a rain gauge on their house. If the public enable GPS on their tweets, those tweets can be plotted. So if some one in the public mentions on twitter than the water is over the front steps and at his door, the local EOC can obtain that location. Then using measurement tools in a software like Pictometry, the current high water mark can be determined. Add that value into the flood warning system as an additional source and now, hopefully the flood delineation will be even more accurate.
Information is literally everywhere now, how the information is implemented is where the value is, in it.