View From Above

There's an African flood every year that drops down like an enormous hand. Five months after the rainfall in February, the Okavango Delta in Botswana-peaking in August as right as rain-spills over like dripping fingers.

People don't die as they do in major floods, though roads become inaccessible. The spreading waters are actually welcomed in this arid land. The groundwater is recharged for vegetation and wells, and wildlife is sustained. Researchers who want to study the biodiversity effects of what becomes the world's largest wetland often take to the air to do so.

One of those researchers, Melba Crawford, a professor with appointments in civil engineering and agronomy, arrived at Purdue this spring semester. After 25 years at the University of Texas at Austin, Crawford was recruited to take the Laboratory for Applications of Remote Sensing (LARS) to new heights. A civil engineer by training, her expertise has been applied in hydrology, agriculture, forestry, archeology, atmospheric science, as well as soil moisture and pollution-related areas. She also spent last year in Washington, D.C., as an inaugural Jefferson Science Fellow at the State Department.

But what is remote sensing? And where will it be applied?

"Remote sensing involves measuring any kinds of phenomena without direct physical contact," Crawford says. "People often think of it in terms of weather satellites, pictures from astronauts on the space station, or aerial photography."

Picture a cropduster making singlelane passes over a field with a camera staring out the bottom of the plane snapping pictures. Crawford, however, likes to think of remote sensing in a whole set of gradations. "There's spacebased remote sensing," she says, "but it's not just photography. These instruments generally involve some type of sensor that measures reflected or emitted energy. It might be related to temperature, precipitation, the height of ice sheets, or something associated with plant or atmospheric chemistry."

Remote sensing is also performed from aircraft, on trucks and tractors, and on the ground, she says. Consider acoustic sensors, Global Positioning Systems, and ground penetrating radar, for example.

Crawford has used remote sensing to study environmental and property-related issues in the aftermath of Texas coast hurricanes, monitor endangered species; habitats at Kennedy Space Center, assess earthquake damage in Algeria, and map wildfires in the Australian outback. Other remote sensing applications could provide a clearer characterization of forests, map soil patterns and different responses of crops through precision farming, and be used in urban areas like Houston and New Orleans to measure subsiding zones. As a technology for homeland security, remote sensing can be used for both planning and response to emergencies.

For a hands-on researcher like Crawford, there are too many projects and not enough air time. Though she says she could either be up in the air or on the ground with the calibration instrumentation. "I love being out in the field, and I still have projects in Texas," she says.

In her own research, Crawford is particularly interested in new laser-based technologies for characterizing vegetation structure and mapping fine-scale topographic variation. As far as LARS is concerned, Crawford is working with faculty to incorporate the most appropriate remote sensing technologies into their research. Her campus presence should also help foster interdisciplinary work. A new ground station for receiving data from satellites is being built here by the Purdue Terrestrial Observatory, a part of Information Technology at Purdue, and she hopes her connections to both engineering and agronomy will spark more crossover work.

"Remote sensing fits very well with spatial technologies and is important to modeling in areas such as climate change," Crawford says. "The data that are acquired must be analyzed. That's where my expertise enters."

As Crawford enters Purdue, she hopes her leadership at LARS will help solve some problems by taking a view from above.