Game-Changing Satellite Shows Flood Area That Everyone Was Missing

This past month brought disastrous floods to the Balkans leaving hundreds dead and thousands displaced.

If not for a new European satellite, one particularly hard hit town, Balatun, wouldn’t have gotten the emergency relief needed.

Flood photos taken from the satellite, Sentinel 1A, showed that current flood mapping had not incorporated Balatun, which lies near the convergence of two rivers.

“I had a first look and discovered that we were missing an important flooded area visible in the middle of the image,” said Jan Kucera of the European Commission’s Joint Research Center.

Kucera is supervising the technical aspects of Emergency Management Services for Copernicus, a global monitoring and security program for which Sentinel 1A was built.

You can see the extent of flooding in Serbia, Bosnia and Herzegovina, and Croatia from May 22nd to the 24th in red picked up by NASA’s MODIS system (purple are urban areas):

Balkins Flooding

But here’s what it looked like to Sentinel 1A on May 24th. Black areas represent water:


The area in the red box above was used to make the map below, showing the flooded areas of the village of Balatun in northeastern Bosnia and Herzegovina. Serbia is just north of the river:


Just the beginning

Sentinel 1 has only been up about two months. It is not yet technically operational and is still undergoing calibration. However, it has already been hard at work monitoring natural disasters worldwide.

Just over a week after Sentinel 1A was launched, it took one of its first images — that of the Zambezi flood. The flood plain is to the left. To the right, is Victoria falls. ESA

The Balkans was not the first instance in which the satellite has provided assistance. Previously, it helped determine the extent of flooding in Namibia.

“Currently, it’s practically impossible to monitor the situation from the ground because accessibility is difficult and virtually impossible during the rainy season,” said Pauline Mufeti, Head of Namibia’s National Hydrological services.

Photo-equipped aircraft are of little use in rainy conditions, because clouds can obscure their view of the ground. When the clouds clear, these planes can still only image small areas at a time. This is why the radar-equipped Sentinel is important: It can detect through clouds and rain and can even image in darkness.

The Namibia map created with the help of the satellite image. ESA/Tiger Net/Dept. of Water Affairs/GeoVille/DHI/TU Vienna/GEO

This means it can provide near real-time views of disaster areas helping decision makers identify those in peril and strategically plan their response.

In the case of April’s Zambezi flood, which flooded parts of Namibia, Zambia, and Botswana, the Sentinel’s satellite data was acquired and processed within several hours.

The graphic below gives you a rough idea of how Sentinel images and what those images can be used for:

“A new era in Earth observation”

Just 10 days after launch, Sentinel 1A took this radar image of the Antarctic Peninsula. The differing colours show how water, land, and ice differentially reflect the radar. ESA

The ESA has called the Sentinels a “new era in Earth observation.” The satellite responsible for the flooding images was Sentinel 1A, just the first of about a dozen to be launched as part of the European Space Agency’s Copernicus environmental monitoring program.

When they are all launched, they will change “the way we manage our environment, understand and tackle the effects of climate change, and safeguard everyday lives,” said the ESA in a press release.

Another of the first images: Brussels with Antwerp harbour on the top left. ‘The green colours correspond to vegetation, red — blue to urban areas, white to high-density urban areas and black to waterways and low-reflective areas such as airport runways,’ said a press release. ESA

Each Sentinel mission consists of two satellites (A and B) outfitted to achieve specific monitoring goals. Sentinel 1 A and B satellites orbit 180 degrees apart imaging the entire Earth via radar every six days. The satellites’ versatility is expected to aid in a wide variety of projects including ice mapping, oil spill monitoring, maritime security, forest mapping, and emergency imaging.

Sentinel 2 will take high resolution optical images, rather than radar like Sentinel 1. 2A is expected to launch April 2015 and B a year later. In addition to emergency use, these satellites are expected to provide land imaging services to aid in forestry, industry, and agriculture.

Future Sentinel missions (3, 4, 5, 5P, and 6) will focus on ocean, climate, and atmospheric monitoring.