The nation has failed to cope adequately with shifts in population from the Frost Belt to the Sun Belt and with a declining growth rate throughout the country, a cogressional committee said yesterday.

Rep. James H. Scheuer (D-N.Y.), chairman of the House Select Committee on Population, said that absolute decline in population of certain cities in the Northeast and Midwest is not "a blessing or a disaster."

"It depends totally on how we cope with it," he said. "Efforts to date have been ill-conceived, chaotic, haphazard, wasteful and sometimes downright cruel."

Scheuer cited his own city of New York, which since 1970 has lost 1 million "middle-income, professional, executive, entrepreneurial people."

Instead of adjusting to having a smaller city with fewer jobs, New York is considering the construction of 100,000 public housing units in the South Bronx, he said.

"That is not management. That is not planning. That is sheer, unadulterated waste," Scheuer charged. "No one appears to have considered whether or not South Bronx is an area that can and should be redeveloped -- and if so, for what purpose and with what goals. Perhaps we should help those who want to leave South Bronx find good housing and jobs in other, more viable parts of the city."

Rep. Daniel K. Akaka (D-Hawaii) said his state has become the first in the nation to adopt a plan for longrange management of growth because it is gaining population rapidly and must import 80 percent of its commodities.

The committee, in a report summarizing its findings after a 13-month study of population shifts, warned that without adequate planning, the nation would repeat the mistakes it made in coping with the "baby boom" of the late 1940s to the early 1960s.

Those mistakes included the failure to build enough schools in the 1950s and early 1960s so that many students were on half-day sessions in overcrowded schools. Then, as the flood of school-age children crested, local officials began overbuilding so that now in many parts of the country there are teachers who are out of jobs and school buildings that are empty.

"The major institutions in this country will face similar disruptions for the next 50 years, as the 'baby boom' generation continues to move through its life cycle, leaving the problems of the 'baby bust' in its wake," the report said.

Rep. John N. Erlenborn (R-Ill.), the committee's ranking minority member, said one problem could be the strain on a smaller working population trying to support a larger number of retired people through the Social Security system early in the next century.

The group's report noted that "in 1910 there were 10 youths under age 18 for every elderly person; by 1977 there were only three youths for each person 65 and over." It predicted that the "baby boom" generation, which will begin to reach age 65 in 2010, will peak as the elderly generation in the year 2030. Then it will constitute 14 to 22 percent of the population, depending on future fertility rates, the study said.

The panel also said that "the 'baby boom' generation may never achieve the relative economic success of the generations immediately preceding it or following it because its large size results in an oversupply of workers in that age group."

But it added that such a result may be offset by the fact that baby boom people have more education than their predecessors.

It predicted the labor force will grow from 83 million in 1970 to 119 million in 1990.

It noted that the population is aging because of low fertility rates and concluded that, since young people push up the crime rate, "we can anticipate lower crime rates in the future if the crime rates of different age groups remain constant."

The committee recommended the creation of some unit, perhaps in an existing federal agency, to monitor population changes and develop ways for the nation to respond to them. It also called for more research on the baby boom generation with a view to predicting future mobility, earnings, needs and social impacts of its members."