Diverting Soviet rivers. Many of the nation's rivers flow north instead of to the arid south, where most Soviet Muslims live. The government has plans to correct these `blunders of nature.'

THE Soviet Union, in a move officially described as ``directed at correcting the `blunders of nature,' '' is embarking on a multimillion-dollar scheme to reroute part of the flow of rivers. Less certain is whether the scheme will eventually be seen as yet another blunder -- this time, by humanity.

Clearly, the Russians have good reason for suspecting that if Mother Nature did not blunder, then she is a co-conspirator in an anti-Soviet plot. For while some of the world's great rivers cut across the expanses of this country, many of them flow north into the Baltic Sea and Arctic Ocean rather than south where the bulk of the population lives.

Official figures indicate that only 16 percent of the annual flow of the country's rivers goes to the southern and central areas where 85 percent of the population is concentrated and 80 percent of industrial production takes place.

Accordingly, the Soviets are planning several leviathan schemes to divert northern rivers to the south.

The significance of the water diversion projects goes beyond their environmental and economic impact. Like almost everything else in this country, they have a political dimension as well.

The southern part of the Soviet Union is where the majority of the country's Muslim population is located. And the rate of population growth in this area far outstrips that in Russia and the European part of the Soviet Union.

The Soviet leadership, well aware of what happened when Iran was gripped by Islamic fundamentalism, is sensitive to anything that might provoke popular discontent in the south and create a seedbed for Muslim extremists.

And the lack of water -- for agriculture, industrial development, and human consumption -- has the potential to be just such an issue.

One official, in a newspaper interview, said, ``The water situation in these regions grows more acute every year.''

For that reason the Soviet leadership is carefully studying plans to send more water southward. Under one plan, part of the discharge of rivers that flow north would be channeled into the south-flowing Volga River in an effort to bring more irrigation water to the southern European part of the Soviet Union. There are some indications, according to Western analysts, that construction on this project has already begun.

But the Russians are apparently still studying an even more ambitious project, estimated to cost tens of billions of dollars, to divert rivers from northern Siberia to Soviet Central Asia.

The Siberian diversion scheme has generated controversy here and in the West, partly because of fears that it might bring about unforeseen climatic changes in the Northern Hemisphere, sparked by a partial melting of the polar ice cap.

The Volga plan has not provoked as much discussion, because it is smaller than the Siberian scheme. Nevertheless, it is a major project in its own right.

Under the plan, some 5.8 cubic kilometers of water would be diverted every year from the Sukhona River and Lacha, Vozhe and Kubenskoye lakes, in the north, through a series of canals, pumping stations, and channels. The water would eventually be discharged into the Sheksna River, then into a reservoir, and finally into the mighty Volga.

It would be used for new irrigation projects in southern Russia, the Caucasus, the Ukraine, and Moldavia. Soviet planners hold that an additional 5 million hectares of land (some 19,000 square miles) will be brought under irrigation, resulting in the production of an additional 500,000 tons of meat, 1 million tons of vegetables, and 400,000 tons of fruit. The project is expected to be completed by 1990.

Government officials say some of the water will also be used to increase city water supplies, to support new industries, and to increase the supply of fresh water to the Azov and Caspian seas.

Polad A. Polad-zade, an official in the Ministry of Land Reclamation and Water Resources, told the government newspaper Izvestia that ``there is no threat of large-scale climatic changes'' and that ``negative effects'' of the project ``can be minimized or even eliminated altogether.''

OTHERS, however, aren't so sure. For one thing, the project will reportedly flood numerous towns and villages. Mr. Polad-Zade, however, while saying that ``researchers and designers are paying special attention to the rich cultural and historical heritage of the Russian north,'' did not indicate how the state would go about preserving ``monuments of antiquity and ancient settlements.''

Concerns have also been expressed about harming fishing in the northern areas, about altering the salinity of the Baltic Sea (into which the northern rivers drain), and about tampering with the ecology of the Caspian and Azov seas.

Indeed, the Soviets have a spotty record when it comes to large-scale water projects. On at least two occasions, they have had to dismantle projects due to unforeseen effects on the environment.

One Western analyst says of the Volga scheme, ``I don't think they know all the environmental impacts yet.''

Another says, ``There's a surprising number of high-level scientists who are against this project.''

It is unclear how that decision will affect the other, more massive Siberian scheme, which envisions the diversion of 27 cubic kilometers of water yearly from the Ob and Irtysh rivers, or about 7 percent of their total flow. Engineers are drawing up plans to channel the water more than 2,550 kilometers (1,600 miles) southward, into Soviet Central Asia and Kazakhstan. Satellites have been used to map possible routes, including ancient riverbeds that are now dry.

There are myriad environmental concerns surrounding the Siberian scheme. One is that a massive rechanneling of water will alter the climate and ecosystems of Siberia and Central Asia in unpredictable ways by drawing water from cold areas into arid, hot ones.

Another is that the polar ice cap might be affected. Scientists say the infusion of fresh water from Siberia's rivers builds up the ice cap; some theorized that, deprived of even a portion of this fresh water, the ice cap might recede -- perhaps permanently. Then, some argue, weather patterns in the Northern Hemisphere might be altered -- although scientists disagree on the possible results.

Ironically, some -- like climatologist Michael Kelly at Britain's University of East Anglia -- theorize that one upshot might be reduced rainfall in parts of the Soviet Union, offsetting gains realized through the river diversion scheme.

It is unclear, however, where the proposal now stands. The Siberian scheme was mentioned during the meeting of the Communist Party's Central Committee in October, but it was certainly not given prominence. ``My interpretation,'' says a Western diplomat, ``is that they have shelved the decision,'' and instead simply called for ``further study'' until the year 2000.

Still, a report last August indicated that preliminary planning had been approved, and that design work had actually begun. One official said the benefits from the project could be realized ``by the end of this century'' -- hardly likely if it remains only in the planning stages until then.

And a dispatch from Tass, the official Soviet news agency, after the latest Central Committee meeting, mentioned the ``upcoming completion'' of the Siberian diversion scheme -- although satellites have not detected any major construction activity taking place.

The diversion scheme appears to have influential backers in Kazakhstan and Uzbekistan, two republics that would receive much of the new water.

Officials in these areas have formed unofficial ``lobbies,'' orchestrated press campaigns lauding the project, and apparently forced the issue on the agenda of the last Communist Party congress in 1981. Presumably, they will attempt to do the same thing at the 1986 congress.

Therefore it seems likely that pressure to approve the plan will increase.

``It's like the Frankenstein monster,'' a Western diplomat says. ``It could be very hard to kill once it gets going.'' -- 30 --