Two Washington area real estate investment trusts have reported banner results for 1980, reflecting gains from their property investments. One of the firms, Washington Real Estate Investment Trust, announced a three-for-one stock split and an increase in the quarterly dividend rate.

WRIT, one of the most profitable trusts in the industry, reported that operating earnings for the year rose 13 percent to $3.5 million ($2.28 a share) compared with $3.07 million ($2.02) in 1979. Gains from an exchange of real estate in 1979 boosted net income that year to $9.4 million ($6.16).

In the fourth quarter, WRIT earnings rose 21 percent to a record $1 million (68 cents) from $853,000 (56 cents) a year earlier.

The trust's stock split will take effect about March 31 for owners of record March 16, President B. Franklin Kahn said. The split "will triple the number of WRIT's shares trading on the American Stock Exchange, increase the trading and liquidity and reduce the price per share to appeal to WRIT's typical shareholder," Kahn added.

Currently, the average WRIT owner has 200 shares; the firm's stock has been trading recently at about $44. WRIT also announced an indicated annual dividend rate of $1 a share (equal to $3 a share prior to the stock split), a payout boost of 10 percent. A quarterly payment of 25 cents will be made March 31 to owners of record March 16.

Federal Realty Investment Trust reported record 1980 earnings of $1.5 million (90 cents a share), up 18 percent from $1.28 million (85 cents) in 1979. Federal's net cash flow from operations jumped 38 percent to $2.7 million.

The trust's performance last year enabled trustees to boost the dividend rate twice in the year to an annual rate of $1.72 a share, or 23 percent higher than a year ago. Federal acquired two shopping centers in April and four in July, helping boost total assets by 58 percent to $61.3 million.