Keeping watch

There are two major causes of grassland fires: natural events, such as lightning or extremely dry and hot weather, and human error, such as a discarded cigarette or electrical fault.

The four methods China adopted to monitor its prairies are observation towers, ground patrols, air patrols and satellite supervision. Each has its own advantages and disadvantages, according to experts.

Satellites are said to cover all grasslands but they can only successfully detect 30 to 50 percent of blazes in a small scale because their resolution power is limited.

Air patrols, on the other hand, offer higher resolution power but cover a much smaller area and is more expensive.

Wildfires are naturally difficult to monitor with satellites as they rely on light during the day and thermal temperatures at night, said a source with the Sichuan meteorological station's agrometeorological center who did not want to be identified.

"When low bushes catch fire, the smoke is not as large as a forest fire, so there's a chance that satellite monitoring efforts may fail, (especially given that) highland temperatures are relatively low and that the perimeter of grassland fires is (often) not significant," the source added.

(China Daily December 9, 2010)