Alexandria prosecutor William L. Cowhig had enough personal income to meet his obligations, according to a key defense witness called yesterday to counter allegations that Cowhig needed bribe money to survive financially.

Testifying at Cowhig's bribery trial in Alexandria Circuit Court, Frank B. Higdon, a certified public accountant, said that Cowhig, with his salary, bank loans, old legal fees and rentals from a small Bahamian resort he owned, had assets of $123,454 available to him. Cowhig's obligations at the time totaled $89,123, Higdon said.

Cowhig is accused of asking for and receiving $32,000 in bribes from Dirgham Salahi, Alexandria's beggest bingo game operator, from Jan 4, 1977, to May 1, 1978 -- the period covered by Higdon's testimony.

Included in the financial analysis is $22,020 in "cash and money orders given to [Cowhig] or mailed to [Cowhig and] not deposited" in any bank account, according to the written "Cash Flow" statement prepared by Higdon. The money came from proceeds of Cowhig's Two Turtles Hotel in the Bahamas, Higdon testified.

The testimony by Higdon contradicted financial aspects of the case presented by the prosecution last week. A prosecution witness, Virginia State Police accountant Coy Ivy, said that Cowhig had financial obligations of as much as $2,000 each month more than he received in spendable salary.

Special prosecutor Edward J. White contended in opening arguments last week that Cowhig's need for moeny had provided the motivation for him to solicit bribes.

Higdon said yesterday that the difference between financial conclusions drawn by the defense and prosecution was due to sources of income that were "ignored" by Ivy and to financial information available to the defense regarding the Bahamaian hotel.

Special prosecutor White vigorously objected that Higdon's testimony was not supported by documents or exhibits. Last night Circuit Court Judge Percy Thornton Jr. ordered Higdon to turn over to White immediately all of the information on which his testimony was based. White is expected to cross-examine Higdon for the first time today.

Cowhig told The Washington Post last July that the Two Turtles had not been a financial success, and that he had been paying only interest in his monthly mortgage installments.

Documents introduced into evidence by the prosecution last week showed that Cowhig had been making the full $1,820 monthly payments since April 1977, and had made interest-only payments of $851 only in January, February and March of 1977.

Last August, Reevers Turnquest, the manager of the small, two-story flagstone hotel, told The Post that paying guests stayed in the hotel's four guest rooms only when two nearby hotels were filled. Turnquest said that the main income-producing area of the hotel at that time was the bar, whose clients were mainly local workers and occasional American sailboat enthusiasts.

Higdon, a former FBI agent who testified that he has practiced as a certified public accountant in Alexandria for 25 years, spent more than four hours on the witness stand yesterday. Defense lawyer Leonard B. Sussholz flashed a photocopy of Higdon's handwritten "Cash Flow" statement on a screen for jurors, who watched in rapt attention as Higdon explained his figures.

Higdon testified that based on "phone conversations" with Turnquest, he concluded that Cowhig's hotel receipts during the 16 months covered by his indictment totaled $52,778.01. Of that, $23,026.01 was kept by Turnquest to reimburse him for improvements he had made at the hotel.

The sum of $22,020 in cash was received by Cowhig or mailed to him from hotel proceeds, Higdon testified. Other figures listed by Higdon under a cloumn marked "Turtles" included $9,561 worth of hotel receipts deposited in a bank account, $660 deposited in the bank account on May 5, 1978, and a $2,500 cashier's check deposited in a bank account owned by Cowhig's wife, Shirley.

Higdon testified that he added $6,027 in savings accounts, $27,000 in loans, $29,379 in spendable income, and several other small amounts to the $52,778 in gross hotel receipts to conclude that Cowhig had a total of $123,454 available to him during the period of the indictment.

After $89,123 in hotel expenses, two loans on airplanes, and the mortgage on the hotel were satisfied, Cowhig had a total available to him of $34,331.24, Higdon testified. The money was "available for anything he wanted to do with it," Higdon said.

White protested that "there is not one scintilla of proof" to back up Higdon's conclusions, at which point Thornton ordered Higdon's documents turned over to the prosecution.