Now, a team of scientists led by Reeves has found a way around this "growing" problem.
The study began as a collaboration between Reeves' faculty advisers, Rosemary Knight, a geophysicist who studies groundwater systems, and Howard Zebker, a geophysicist and electrical engineer who uses satellite-based remote sensing techniques to study the Earth's surface. Knight and Zebker hoped that the combination of their expertise, and the efforts of their graduate student, would lead to new ways of using satellite data for groundwater management.
Reeves analyzed a decade's worth of surface elevation data collected by satellites over the San Luis Valley in Colorado. Although the valley is rich with growing crops, Reeves and her advisers hoped that recent advances in data-processing techniques would allow her to gain an understanding of the aquifer that lay below.
As part of her analysis, Reeves produced maps of satellite measurements in the valley and saw a regular pattern of brightly colored high-quality data in a sea of dark, low-quality data. After overlaying the maps with a Google Earth image of the farmland, the team realized that the points of high-quality data were in the dry, plant-free gaps between circles of lush crops on the farms.
In the San Luis Valley, the majority of irrigation is done by center-pivot irrigation systems. Like a hand on a clock, a line of sprinklers powered by a motor moves around, producing the familiar circles seen by airline passengers.
The circles don't overlap, leaving small patches of arid ground that don't receive any water and so don't have any plants growing on them.
Reeves confirmed that these unvegetated data points were trustworthy by comparing the satellite data to data collected from wells in the area exactly the kind of proof that would be important to hydrologists studying aquifers.
The satellites use interfe
|Contact: Louis Bergeron|