For the last 10 years, J. Kenneth Robinson has represented the predominantly Republican 7th Congressional District, which covers nearly one-fourth of Virginia.

In the last decade, however, the suburban sprawl of Northern Virginia has spilled into Robinson's massive district in the middle of the state, bringing with it many new Democratic voters.

So it is with some trepidation that Robinson, a five-term Republican from Winchester, views the congressional redistricting process that began in Virginia this week, because new boundary lines will be drawn by the Democratic-controlled General Assembly.

Rep. Joseph L. Fisher, an Arlington Democrat, testifying before a joint meeting of the assembly's House and Senate committees on privileges and elections, implored his fellow Democrats to "avoid the mischievous gerrymander."

Fisher told committee members, who met Monday at the Arlington County Courthouse, that "every political leader must acknowledge that he would like a safe election district for himself and his party."

Robinson did not attend the hearing, but sent a statement.

"I like the district the way it is," he wrote, but conceded "population figures have given stern notice that the status quo cannot be maintained."

Population estimates prepared by the Virginia Department of Planning and Budget, which the General Assembly will use as guidelines until official 1980 census statistics are available, set Virginia's 1980 population at 5,313,000. If the estimate is accurate, that would be an increase of 664,506 over the state's 1970 population of 4,648,494.

Despite the expected increase, Virginia has not gained enough to add an 11th congressional district. So the mathematically ideal district, following the one-person, one-vote rule, would contain 531,300 persons.

Robinson's current district has a population of 595,000, which is 64,000 or 12 percent, more than it should be.

State Sen. Hunter B. Andrews (D-Hampton), chairman of the Senate privileges and elections committee, dismissed most of the concerns. The worries about gerrymandering are "created by you fellows (in the press)," he said, adding that the process of redrawing congressional boundaries is "not as political as you think."

Andrews said the U.S. Supreme Court's one-man, one-vote rule before the 1970 redistricting makes the process a "mathematical one." The state constitution, he added, requires the districts be, as far as is practical, "compact and contiguous."

Despite Andrews' assurances, some Republicans are concerned Richmond lawmakers may follow a tradition that began in Boston in 1912.

To ensure the election of Gov. Elbridge Gerry to Congress, the friendly Massachusetts legislature concocted a district that was shaped like a salamander. After Gerry won, the term gerrymander came into the political lexicon.

Besides the 7th, the district that deviates most from the ideal size is Northern Virginia's 8th, represented by Democrat Herbert E. Harris II of Fairfax.

Because the 7th and 8th adjoin, the redistricting process will cause "dominos to flop all over the central part of the state," Andrews said.

Harris told legislators Monday that his only advice to them was "the current divider between the 8th and 10th (Fisher's) congressional districts is easily recognizable to voters and should be preserved."

The two Northern Virginia districts are roughly divided along Rte. 236 (Little River Turnpike) near the Potomac River and Rte. 50 beyond Fairfax City, with 8th south and the 10th north of those roads.

While Harris' district has 52,800 too many residents, Fisher's district has 12,600 too few.

The third congressman who testified Monday was G. William Whitehurst, a Republican from Virginia Beach.

Whitehurst offered several "general principles" that he said should guide legislators in drawing new congressional maps.

"Any connection between my view of the public interest and my own self-interest is, of course, purely accidental," said Whitehurst, prompting smiles from several of the 27 legislators at the hearing.

Whitehurst's big pitch was to leave Norfolk and Virginia Beach in his 2nd District. He said that adding the 31,800 Virginia Beach residents who currently vote in the 4th District to his own "would constitute an almost ideally sized congressional district." Virginia Congressional Districts (TABLE) (COLUMN)(COLUMN)Population(COLUMN)Projected District(COLUMN)Representative(COLUMN)(1980 Est.)(COLUMN)Change 1st(COLUMN)Paul S. Trible (R)(COLUMN)528,800(COLUMN)+2,500 2nd(COLUMN)G. William Whitehurst (R)(COLUMN)500,700(COLUMN)+30,600 3rd(COLUMN)David E. Satterfield III (D, retiring)(COLUMN)494,500(COLUMN)+36,800 4th(COLUMN)Robert W. Daniel Jr. (R)(COLUMN)512,500(COLUMN)+18,800 5th(COLUMN)W. C. (Dan) Daniel (D)(COLUMN)537,900(COLUMN)-6,600 6th(COLUMN)M. Caldwell Butler (R)(COLUMN)490,600(COLUMN)+40,700 7th(COLUMN)J. Kenneth Robinson (R)(COLUMN)595,400(COLUMN)-64,100 *8th(COLUMN)Herbert E. Harris II (D)(COLUMN)584,100(COLUMN)-52,800 9th(COLUMN)William C. Wampler (R)(COLUMN)548,800(COLUMN)-17,500 *10th(COLUMN)Joseph L. Fisher (D)(COLUMN)519,700(COLUMN)+11,600(END TABLE) *Northern Virginia Districts