CHANGSHA, Nov. 13 (Xinhua) -- China's second-largest freshwater lake has expanded 28.9 percent over the past 40 years as local authorities returned farmland and relocated residents to make room for the lake to increase its flood control capabilities.

Since 1978, the area of Dongting Lake in central China's Hunan Province has increased by 779 square kilometers to 3,470 square kilometers, according to the Hunan provincial bureau of water resources.

Dongting Lake, which links with the Yangtze River, was once the country's largest freshwater lake. Due to sediment accumulation and farmland reclamation, the lake shrank to 2,691 square kilometers in 1978 from 4,350 square kilometers in 1949.

Its flood storage capacity was then reduced, thus raising the flood control risk downstream in the middle and lower reaches of the Yangtze River.

Since the massive flooding in 1998, local authorities have relocated residents and sped up the returning of farmland to the lake to boost the flood control capabilities.

Over the past 20 years, local authorities have demolished 333 dykes and relocated 558,000 people, said Zhan Xiao'an, director of the Hunan provincial bureau of water resources.

In addition to the efforts to boost flood control, local authorities will also strive to send more water into the lake during the dry season to improve its ecological environment, said Zhan.