Geography Professor G. Robert Brakenridge spent the past week in the Mississippi and Illinois valleys gathering data in flooded regions to test the ability of a new satellite to view the ground through cloud cover.
In the "ground truth" project, Brakenridge and James Knox, geography professor at the University of Wisconsin at Madison, are correlating photographs and direct observation with recent radar images of the Midwest flood area taken through cloud cover by the satellite.
They are supported by a $3,800 emergency grant from the National Geographic Society.
The European Remote Sensing Satellite, known as ERS1, is considered a technological breakthrough in the study of floods because it uses an imaging process that can capture water and land through cloud cover, something difficult to do with photography and other kinds of optical images, Brakenridge said.
Brakenridge and Knox traveled on August 12th to the Midwest to help in the interpretation of the satellite radar images.
The professors stayed for five days, concentrating their study on the Davenport, Iowa area and on the confluence of the Mississippi and Missouri rivers north of St. Louis.
On the 13th Brackenridge and Knox participated in a low fly-over of the flood areas in a plane about 900 feet above ground level, with radar images in hand. Through this, other ground-level observation and conventional optical photography, they learned about the satellite and other important elements to their study of flooding.
Unlike photographs, radar images are made up mainly of light and dark radar reflections rather than readily identifiable features. As a consequence, the images are difficult to interpret. This is the biggest downfall to the new satellite radar, according to Brakenridge.
However, water creates a distinct dark radar reflection on the satellite image and is easily distinguishable from other images, according to Brakenridge.
"Therefore, what we see on the satellite image accurately depicts what is present on the ground," Brakenridge said.
The purpose of satellite research and observation is to learn how to accurately study how floods develop through time, particularly how they progress down stream, Brakenridge said.
"We are particularly interested in the erosion and sedimentation associated at the flood crest," Knox said.
Other points of interest include the effect of the flood on the valleys' living organisms and the thinning of the flood flow itself as it moves down stream, Knox said.
The Mississippi and Missouri rivers are vast and expansive and create particularly large areas to research in the Mississippi and Illinois valleys, according to Knox. The ERS1 radar helps the professors to get a handle on the size of the task at hand and to determine the exact location, size and root of the river's tributaries.
ERS1 gives the professors the opportunity to see a continuous visual account of the flood even though the weather may be cloudy. "This is the principle advantage of the satellite," Knox said.
The photos produced by the satellite are similar, in principle to those of time lapse photography, following the flood from its very beginning until it reaches its maximum level, Breckenridge said.
"One should think of the satellite radar images as a movie of the flood, or as a series of pictures showing the anatomy of the flood," Brakenridge said.
The satellite pictures are able to capture the entire valley of interest, allowing the researchers to see the geographical distribution of the flood at any point and time, or a simultaneous view of the entire geographical district at once, Knox said.
"This is particularly valuable in the case of the Midwest flooding," Knox said.
The massive flooding in the Midwest this past year, the biggest on record, serves as an ideal field of study, as such widespread flooding has not happened before in this century, Knox said.
The two geology professors plan to work on this and other projects together by communicating through electronic mail, according to Knox.
