Flooding is a problem in underdeveloped, emerging and even developed countries and can be a problem in low lying rural, suburban and even urban areas where drainage is less than optimal or has been compromised. Every year people die from drowning as a direct consequence of flooding situations. Even after the event that triggered the flooding ends, unforeseeable dangers can still be present in the areas where stagnant or slow draining water remains. Such circumstances can present a greater hazard specifically because the flood cause has ended, since people will be more inclined to discount the danger.
In some cases, this can be because of their lack of awareness of situations that did not exist prior to the flood, for example, channels cut by the original moving water, sinkholes or depressions, displaced manhole covers, etc., rendering the water in some places deeper than it might appear from the surface or would be presumed based upon a person's knowledge of the pre-flood topography. In such cases, even persons familiar with the highly local topography of that specific area may be misled into thinking that it is safe to cross the remaining water, because they are unaware of the changed situation under the water. For example, an adult attempting to cross a flooded street to safety by wading through what appears to them be about 0.5 meters (about 2 feet) to 1 meter (about 3 feet) of non-flowing water could easily find themselves in grave danger if the water conceals an open manhole directly in their path or a deep channel or sinkhole, caused by the previously flowing water, is now in their path.
In an attempt to prevent some drowning situations in commonly flooded or flood-prone areas, permanent infrastructure may be installed to warn people regarding the depth of the water at a point in the topography known to be the lowest point. Those warning systems may be as simple as poles with markings to indicate height of the water or more sophisticated warnings that rely upon floats or other technology. Such warning systems operate under the premise that, if one knows the depth at the lowest point, everywhere else will have a lesser depth. However, as noted above, those warning systems operate in the specific place where they are located and typically will not be able to account for flood-caused topographical changes, even nearby.
Moreover, such indicators cannot typically be used in, for example, the middle of a roadway, and, being fixed in place, cannot account for unusual flooding circumstances or a flood situation in locations where flooding is not common.
More recently, in the attempts have been made to identify areas where hazards exist, for example flooding, and to put out alerts via the mobile phone networks to warn persons in the area. For example, in the United States, the mobile industry, along with the Federal Communications Commission (FCC) and Federal Emergency Management Agency (FEMA), developed the Wireless Emergency Alerts (WEA) to send concise, text-like messages to users' WEA-capable mobile devices to alert users to, for example, imminent threats that include severe man-made or natural disasters, such as hurricanes, earthquakes, tornadoes, etc., or other circumstances where an imminent threat to life or property exists.
WEA use a point-to-multipoint system, so that alert messages are only sent to those within a targeted area, unlike phone, e-mail, text messages which are not location dependent. Thus, if a New York resident is in Arizona and has a WEA-capable device, and a flash flood warning issues for that area of Arizona, their device would receive an “Imminent Threat Alert” because they are within the designated area for the alert. However, alerts are no more than 90 characters, and generally only include: (i) who is sending the alert, (ii) what is happening, (iii) who is affected, and (iv) what action to take.
Canada has implemented a similar system to provide alerts via all television stations, radio stations, and broadcast distribution undertakings. In addition, the province of Alberta has its own system that broadcasts emergency and information alert messages through RSS feeds, social networks, and mobile apps.
In Europe, European Flood Awareness System is involved monitoring and forecasting floods across Europe. It provides complementary, flood early warning information up to 10 days in advance to its partner entities including the European Emergency Response Coordination Centre which collects and analyses real-time information on disasters, monitors hazards, prepares plans for the deployment of experts, teams and equipment, and works with Member States to map available assets and coordinate the EU's disaster response efforts.
In Japan, the Japan Meteorological Agency issues warnings for meteorological phenomena such as heavy rain, storms, storm surges, high waves, heavy snow and snowstorms and disseminates them through television, radio, internet and loudspeaker vans.
While these systems are a significant improvement in some cases, they are all clearly intended for broad general warnings, typically before the fact, and do not provide sufficient granularity to address highly local, let alone surface-invisible, unusual situations.
Moreover, such alert systems don't exist at all in less developed locations in many parts of Asia where variable flooding is an ongoing problem.
Thus, there is a significant technological problem regarding determining local flood depth conditions over a given local area, and providing alerts relating to local occult flood-caused conditions, in flooded areas where flooding is uncommon. Moreover, this technological problem potentially exists even within commonly flooded areas because, as noted above, local conditions can vary unexpectedly due to flood-caused hazards or changes in topography or due to particular unusual circumstances.