Miami braces for a new wave of Cuban 'emigr'es. CUBANS IN THE US

The new immigration accord with Cuba - allowing up to 27,000 Cubans a year into the United States - has neither the magnitude nor the suddenness of the 1980 Mariel boatlift. But in Miami it has set off some old alarms.

Even before they set foot in south Florida in 1980, the refugees from the port of Mariel were tagged as the sweepings of Cuba's prisons and mental hospitals.

It was true only for a small percentage of the Marielitos, but the sudden arrival of 125,000 refugees was a shock that Miami is still recovering from.

Miamians have little doubt that most of the new immigrants from Cuba will follow the old directly to Miami. They also recall getting only a small part of the federal aid for resettling the Mariel refugees that President Jimmy Carter initially promised. Hard-line Cuban exiles also suspect that Cuban President Fidel Castro will use the new immigration to his advantage, just as he did during the 1980 exodus.

Without offering any substantive concessions to the US, notes Jaime Suchlicki, a University of Miami political scientist, the agreement allows Mr. Castro to relieve some discontent with Cuba's sputtering economy by letting restless people out.

Most Cubans in Miami see the new immigration accord in more personal terms - as a chance to reunite families. The bulk of the new immigrants, up to 20,000 of them, are chosen by the same elaborate system of preferences used for other countries. The system favors relatives of US citizens, then legal residents, then people with skills needed in the US. Immediate family members of US citizens and Cuban political prisoners are allowed in without limits.

Many Cubans exiles saw the 1980 influx in family terms as well, and sailed to Mariel to pick up uncles and grandparents, only to find that they were told to pick up strangers as well. By now, the vast majority of the Marielitos have been absorbed into the community as productive citizens, mostly in and around Miami.

Absorbing them, however, was a tremendous cost to local governments and Florida for schools, hospitals, and other services. Miami's Dade County figures that the federal government still owes it $40 million to $45 million in reimbursement. The city of Miami has received less than half its $35 million cost

The impact of the new immigrants will be much more orderly and gradual, but officials are still concerned about the cost. Sen. Bob Graham (D) foresees a possible ``reprise'' of the Mariel boatlift, where the burden of a federal immigration agreement falls on state and local governments.

Even though the new immigrants would be screened for family support in the US, many will still end up as public charges, says Bobby Bernal, assistant manager in Dade County. The county wants assurances of federal help.

Historically, Cuban immigration to the US has come in fits and starts. ``It has always been controlled by Castro,'' says Thomas Boswell, a University of Miami expert on Cubans in Miami. Castro, sooner or later, will abrogate the new agreement, he adds. ``He'll get mad and he'll cut it off.''

Dr. Boswell predicts that, as in past influxes, about 75 percent of new Cuban immigrants would settle in the Miami area with another 10 to 20 percent in the New York-Union City, N.J., area.

The immigrants will probably be an average sample of Cuban society, he adds. Since the elite immigrants of the early 1960s, succeeding waves of immigration from Cuba have been increasingly less skilled.

Their reputation, however, was set largely by the violent criminals among them.

Criminologist Geoffrey Alpert figures that 12 to 15 percent of the Mariel Cubans were criminals - half of that number so violent and dangerous that they helped make Miami the nation's murder capital in the early 1980s.

Many of the most hard-core criminals literally killed each other off. Others are serving prison sentences or are detained in the riot-torn Atlanta penitentiary.

Another repercussion of the Mariel influx is the mass hiring required in the city police department and subsequent corruption probe that has affected close to one of every 12 officers.

Experts look for causes both in Miami's role as a major cocaine transshipment point and in the way the department was swamped with rookies in the early 1980s. Most of the suspect officers were hired in response to the boatlift and a smaller Haitian influx at about the same time.