2010 a Watershed Year for Floods, Droughts?

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PHOTOS: 2010 a Watershed Year for Floods, Droughts?

PHOTOS: 2010 a Watershed Year for Floods, Droughts?



This gallery is part of a special National Geographic News series on global water issues.



Pakistan flood

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2010-12-17 16:00

Mohammed Nawaz was rescued by the Pakistani Navy on August 10 in Sukkur, Pakistan, as floods swept through the country. At the peak of the flooding, the worst in decades, a third of the country sat underwater.


The deluge left at least 1,500 dead, tens of millions displaced, and millions of acres of agricultural land in ruin.


Ironically, some water engineers and environmental groups point to farming as a catalyst for the disaster. Pakistan has the world's largest contiguous irrigated landscape, with riverside agriculture and human-made canals replacing natural floodplains, wetlands, and river flows that would traditionally hold more water and ease flooding.

A recent study points to another reason for increased flooding: the water cycle is speeding up. Using satellite observations, NASA and university researchers have found that rivers and melting ice sheets delivered 18 percent more water to the oceans in 2006 than in 1994. The findings, which National Geographic Freshwater Fellow Sandra Postel blogged about in October, suggest that the volume of water running off the land toward the sea is expanding by the equivalent of roughly one Mississippi River each year.

Why is the water cycle speeding up? "As the atmosphere warms from the addition of carbon dioxide and other greenhouse gases, it can hold more moisture," explains Postel. "As a result, more water evaporates from the oceans, leading to thicker clouds that then dump more rainfall over the land. That heavier-than-normal rain can then produce massive flooding as it runs back toward the sea, where the cycle begins all over again."



Pakistan Drought


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Pakistani teenagers make a long trek out of a shrunken swimming hole at drought-ravaged Simli Dam, about 15 miles (25 kilometers) from Islamabad, in a photo taken June 22.

A lack of rain earlier this year forced Pakistan to drain its reservoirs and groundwater supplies, before floodwaters hit at the end of July.

As climate change tightens its grip on the world, scientists predict more extreme drought and flooding events. In 2010 several countries experienced disastrous flooding and drought back-to-back. This presents significant challenges, especially in developing countries, where capacity to store rain water and glacial melt is limited. At stake is food security, public health, and the stability of cities and towns.



Amazon Drought


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Hard-hit by a months-long drought, a waterway within the Amazon Basin trickles to a halt in Manaus, Brazil (see map), on November 19.

The Negro River, a major tributary of the Amazon River, dropped to a depth of about 46 feet (14 meters)—the lowest point since record-keeping began in 1902.

About 60,000 people in the Amazon have gone hungry as falling river levels paralyzed transport and fishing. Millions of dead fish have also contaminated rivers, leading to a shortage of clean drinking water, the Reuters news agency reported.

Caused by El Niño—a cyclical warming of tropical waters in the central and eastern Pacific Ocean—such a severe drought usually occurs once in a century. But the 2010 disaster comes just five years after the latest Amazon "megadrought," according to Reuters.



Sinkhole in Guatemala

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A huge sinkhole in Guatemala City (map), Guatemala, crashed into being this May, reportedly swallowing a three-story building.

The sinkhole was likely weeks or even years in the making until floodwaters from tropical storm Agatha caused the sinkhole to finally collapse, scientists say.

Sinkholes are natural depressions that can form when water-saturated soil and other particles become too heavy and cause the roofs of existing voids in the soil to collapse. Another way sinkholes can form is if water enlarges a natural fracture in a limestone bedrock layer. As the crack gets bigger, the topsoil gently slumps, eventually leaving behind a sinkhole.

It's unclear which mechanism is behind the 2010 Guatemala sinkhole, but in either case the final collapse was sudden.




Hungary's Toxic Mud Spill

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2010-12-17 16:00

Triggered by a reservoir collapse in early October at the Ajkai Timfoldgyar alumina plant in the town of Ajka (map), Hungary, a toxic-sludge flood devastated seven towns with contaminated water, fouled fields, and wrecked ecosystems. Alumina, or synthetic aluminum oxide, is used in the smelting of aluminum.

Hungarian authorities reported that at least four people were killed in the wake of the fast-moving, 35-million-cubic-foot (1-million-cubic-meter) flood. Hundreds more were injured or forced to evacuate.

The reservoir failure was the latest environmental insult to Europe's Danube River. But it is not the first, nor the worst, disaster of its kind, experts say.
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