Social Sciences

View From Above

Geography team hits the water with NASA satellite mapping project
satellite

How much do we really know about the world’s water and how it ebbs and flows?

Not a lot, it turns out.

These days, it’s easy to assume everything on Earth has already been thoroughly charted. Google Earth has mapped the planet’s most remote spots and smartphones give us turn-by-turn directions to just about anywhere we want to go.

Water, though, remains elusive. Sure, we can find every river, lake, reservoir and wetland on a map, but we still can’t see how much water is in them and how this changes over time. We just don’t have the crucial information that could help farmers plan crops, allow scientists to see how warmer temperatures are shrinking lakes and enable communities to prepare for flooding.

But soon our knowledge of the world’s water will increase by an order of magnitude.

In 2020, NASA and the space agencies of Canada, France and the United Kingdom will begin using equipment in space to tell us much more about this resource covering most of our planet. Under a project called Surface Water Ocean Topography or SWOT, the agencies will launch a satellite for the collection of valuable information about the world’s lakes, rivers, wetlands and oceans.

Roughly the size of a Prius, the satellite will orbit 550 miles above Earth. Powered by supersized solar panels on either side, it will need just 100 minutes to complete each circuit of the globe.

Three radar “eyes”—one on the main body and the other two on wing-like arms—will bounce radio waves off Earth, measuring the length of time it takes those signals to travel down and back. With this information, researchers can calculate water heights to within a few centimeters, creating a comprehensive and ever-changing picture of the planet’s surface waters.

“It will be like making an extremely high-resolution map every two or three weeks,” geography professor Mark Fonstad said.

Launching a first-of-its-kind technology into space takes years of preparation, and that’s where Fonstad and his team of undergraduate and graduate students come in. They’re working with the US Geological Survey to test and tweak the SWOT technology before it’s operational.

technology on the river

UO geographers paddled the Willamette River, recording water height to calibrate the NASA equipment.

During two days in spring 2015, Fonstad and his students paddled the Willamette River between Eugene and Corvallis in a green-and-yellow cataraft and a handful of kayaks. Onboard, they had sonar and some of the world’s most precise mapping equipment, which allowed them to collect real-time measurements of water heights in precise locations all over the river.

Meanwhile, high above them they caught occasional glimpses of a NASA airplane flying the same route, and using the same SWOT technology that the satellite will carry to collect data about bodies of water.

Comparing on-the-water data with readings from the SWOT radar, researchers can calibrate the satellite equipment. They can also fine-tune the calculations that convert raw data into information about how much water is currently in a river or stream, how fast it is flowing and where it is in relation to flood levels, for example.

Ultimately, that kind of highly detailed information will be shared with people and nations everywhere.

Said Fonstad: “One of the biggest challenges in water resource management is uncertainty—not having knowledge about how much water is where at a given time.”

—Kit Alderdice

Top photo caption: A satellite the size of a Prius will orbit 550 miles above Earth, circling the globe in 100 minutes.