flood

Flooding is a remarkably common phenomenon around the globe. Satellite imaging companies often try to capture imagery of the floods as such imagery is useful for governments and emergency services. DigitalGlobe, for example, has its First Look program through which it captures imagery and distributes it to emergency responders. Today we are looking at a few locations that we know about via the FirstLook program and where the imagery has since made its way into Google Earth. However, none of the imagery in today’s locations really captures the full scale of the events. This is due to a number of reasons:

• There is often no warning for floods. There may be warning for particular types of well-known weather systems such as cyclones and typhoons, or when there are heavy rains in a region the rivers downstream may be expected to flood. But even so, the severity of the flood is hard to predict.
• Floods follow rain and there are often cloudy conditions during and shortly after a flood, so it may take some time before there are suitable conditions for capturing imagery.
• In the case of flash floods the event is typically over before the location can be imaged, so all we can expect to see is the damage caused, such as houses or roads washed away.
• Google only puts high quality imagery in the default layer (more on this at the end of the post).

Eastern Sudan – July / August 2016
In late July and early August there were heavy rains and subsequent flooding in eastern Sudan. According to this article tens of thousands of people were affected and thousands of homes damaged or destroyed. There is a DigitalGlobe image of the town of Sennar and surrounding areas that was captured in response to the floods. Although there is a lot of standing water in the image, we could not find any flooded houses or evidence of houses washed away.

Skopje, Macedonia – August, 2016
In early August, 2016, Skopje Macedonia experienced severe flash flooding, killing at least 21 people. See this article for photos. In this case the imagery in Google Earth comes from CNES / Astrium. We can see some flooded areas, but the imagery does not quite cover the worst affected area (the northern parts of Chento).

Chetwynd, Canada – June, 2016
Chetwynd, Canada, experienced severe flooding in June, 2016 prompting a state of emergency to be declared. There is a DigitalGlobe image of Chetwynd captured after the event. Although we can see wet areas we could not find any washed away roads or bridges. We believe that the worst damage took place in areas not covered by the image.

Wuhan, China – July, 2016
The city of Wuhan was just one of many locations in China that experienced severe flooding in July. There is a CNES / Astrium image captured after the worst of the floods had already subsided, but the river is still very full, flooding some of the buildings along its banks.

In all the above locations we are looking at the imagery in the default layer. There is almost certainly more imagery hidden in ‘historical imagery’ that Google has chosen not to put in the default layer. However, Google has not updated ‘historical imagery’ since early June so we can’t see it. We should also mention Pekalongan City, Indonesia which experienced flooding in June, 2016. We can see bits of a Digital Globe image, but the parts we can see do not cover the affected area.

To see the locations above in Google Earth, download this KML file. We have marked out the extent of the relevant imagery in each location.