Germany is braced for a dramatic increase in migration this year from Soviet Central Asia, where nearly 2 million so-called Volga Germans have lived since their expulsion from European Russia during World War II.

The Volga Germans are descendants of farmers who were invited in the 18th century by Russia's German-born ruler, Catherine the Great, to colonize the Volga River basin. Under German law, they have automatic rights of reentry and citizenship.

They have been coming back to Germany in growing numbers, from a trickle of 753 in 1986 to 147,950 last year, according to the German Interior Ministry. Now, with the Soviet economy in crisis and its legislature about to pass an emigration law waiving the need for exit visas, those ethnic rights may be claimed by even more.

Some Western specialists have estimated that half the Soviet Germans will leave by 1995. If Moscow does not address their concerns, one U.S. official said, "the Soviets will lose 1 million Germans."

Neither Bonn nor Moscow wants that to happen. For the Soviets, it would mean losing hundreds of thousands of productive farmers and workers. For the newly unified Germans, it would compound the problems of integrating the 16 million former East Germans into the Western economy.

To keep the Soviet Germans from leaving, however, the Kremlin must find a homeland for them somewhere in Europe. They "want to retain their identity as ethnic Germans," German Chancellor Helmut Kohl said in a 1989 radio interview, adding that they "hope that an ethnic German territory or republic can again be set up there."

There are two chief possibilities for resettlement. One is a return to the prewar Volga German autonomous republic, established by Lenin in the early days of the Soviet Union and abolished by Joseph Stalin in August 1941, when he deported the ethnic Germans to Kazakhstan after the Nazi army invaded. A resolution proposing the republic's restoration was passed by the Soviet legislature in November 1989, but was shelved after strong opposition from the military and the region's current residents.

The other possibility is a sliver of prewar East Prussia, a triangle of Baltic coastline sandwiched between Lithuania and northeastern Poland that Stalin grabbed for the Soviet Union at the 1945 Yalta conference. Known as the province of Kaliningrad after its main city, the former East Prussian port of Koenigsberg, it is formally part of the Soviet Union's Russian republic -- although separated from it by two other republics -- and houses the major Soviet naval base of Baltisk.

While no plebiscite has been held to determine the wishes of the Volga Germans, who are largely scattered in farming communities across the northern part of the Central Asian republic of Kazakhstan, a Rebirth Society organized by their leaders has continued to press for a return to the fertile Middle Volga region. Kaliningrad, a U.S. official noted, is a polluted industrial area with no potential for agriculture.

But the Kaliningrad option has some powerful backers. A series of articles advocating it was published in 1989 by the government newspaper Izvestia, and Germany's huge Deutsche Bank has proposed turning the former Koenigsberg into a duty-free port for Western goods bound for the Soviet heartland.

Kaliningrad's neighbors are less enthusiastic. Poland, invaded by Nazi armies in 1939 after a dispute over German access to another Baltic enclave, the German-populated free city of Danzig (now Gdansk), is nervous about the possibility of again finding itself between Germany and an isolated German community. According to a Polish diplomat, Foreign Minister Krzysztof Skubiszewski raised the Kaliningrad issue with Soviet officials during his visit to Moscow last fall but heard nothing to calm his concerns.

In a meeting last summer with leaders of the Rebirth Society, Soviet Deputy Prime Minister Vladimir Gusev, whose duties include setting government policy on Soviet nationalities issues, proposed official recognition for the Volga Germans as a nationality group, but with no territory of its own. According to an account published in the Volga German newspaper Freundschaft (Friendship), one delegate responded by asking acidly whether Gusev was proposing a "Palestinian solution."