Dams on demand.

In a project that makes Western engineers cringe, explosives experts in Moscow are planning to trigger a huge landslide in the mountainous country of Kyrgyzstan with the aim of building the world's second largest dam.

While this plan, called the Kambarata dam project, raises a long list of troubling issues, investigators interested in giant landslides see it as a rare opportunity. Geologists normally happen upon landslide scenes long after the action has ended. Scrutinizing a mass of lifeless rubble, they try to recreate what happened hours or thousands of years ago. The Kambarata project would present U.S. investigators with their first chance to witness a giant slide in motion.

While the potential research bonanza does not in itself justify the Kambarata plan, landslide investigators would love to be there if it is going to occur, says Bruce Murray of the California Institute of Technology in Pasadena.

American scientists first learned of the Kambarata dam plans two years ago at a pair of workshops, in Pasadena and in Moscow, on giant landslides. Discussing their research, Soviet scientists revealed that for decades they have triggered landslides with explosions, including underground nuclear blasts, says H. Jay Melosh of the University of Arizona in Tucson. While some of these landslides occurred as unintended by-products of explosions, a few were experimental slides used to build small dams in central Asia.

The Kambarata project calls for the creation of two separate dams: one about 70 meters high, the other roughly 270 meters high with a volume of about 112 million cubic meters. Located in a narrow granite gorge of the Naryn River, the dams will deliver hydroelectric power for the central Asian nation of Kyrgyzstan, a former republic in the Soviet Union. Plans for the project require a whopping 275 kilotons of conventional explosives to trigger the series of landslides that will create the larger of the dams, according to project leader Vitaly Adushkin, director of the Institute for the Dynamics of the Geospheres in Moscow.

Conceived before the Soviet Union collapsed, the Kambarata project has since been postponed as Kyrgyzstan tries to find the necessary funds. Last spring, Adushkin's group announced that construction of the main dam will occur in the year 2000 instead of 1997, as earlier planned.

In the United States, investigators are seeking funds to perform experiments during the Kambarata landslide. These avalanches can't serve as true representations of long-runout landslides because they will come down one side of the canyon and quickly run into the opposite side. But geologists can't afford to be choosy. This is the closest to a giant landslide they will ever get.

U.S. researchers have dreamed up a number of possible experiments, ranging from the simple to the sophisticated (and expensive). On the cheaper side, some suggest painting sections of the canyon with different colors and then tracking the colors as they fall. More complicated experiments would involve embedding transmitters within artificial rocks that would accompany the rest of the slide. By tracking the transmitters, researchers could discover how rocks within the slide moved.

While the project has captured the interest of U.S. landslide researchers, several engineers who have learned about the Kambarata plan express reservations. "It's not a good way to build a dam," says Ronald F. Scott, a Caltech engineer who studies dams and their safety during earthquakes.

Normal earthfill dams have a number of features that make them impermeable and strong. But landslide dams are more like a pile of rocks than a well-constructed dam. What's more, this region of Kyrgyzstan is prone to large earthquakes, as demonstrated by a magnitude 7.5 shock that caused considerable damage there last week. "I would not feel at all comfortable about the seismic resistance of such a dam," says Scott.

Adushkin told SCIENCE NEWS that the landslide method is an inexpensive way to construct dams. But Scott believes the impetus to build dams through landslides may come not from economics but from a community of explosives researchers facing unemployment with the demise of the Soviet weapons-testing program. Scott adds that the landslide method may not end up any cheaper than other methods, because workers will have to spend considerable time shaping the Kambarata dam after the landslide.

Alexander Potapov, a former researcher at Adushkin's institute, says, "As far as a stable job, the [Kambarata project] is probably the only real work that will be 100 percent sure in the future" for physicists who had previously studied nuclear explosions. The government of Kyrgyzstan is very interested in building a hydroelectric dam and will be willing to pay, says Potapov, now a postdoctoral researcher at the University of Southern California.

At present, though, many researchers in the United States and Russia are wondering whether the Kambarata project is likely to move forward anytime soon, if ever. The official plan calls for building the smaller of the dams in 1994, but some Russian researchers do not take that date very seriously.