Based on the mixed pixel decomposition of remote sensing data, the Hongjiannao Lake area is extracted by making use of Landsat data. The Hongjiannao Lake area shrank by 19.7 km2 during 1973—2009, and the change rate was -34%. In the 1970s, the lake area was bigger and showed little change, and the largest was 59.97 km2 in 1974; It reduced rapidly in the 1980s, and the change rate was -12.4%; In the 1990s, the change rate became smaller, it was -10.6%; The lake area reduced faster in the 2000s, and the change rate reduced to -16.6%, and the lake area was only 38.33 km2 in 2009. As for its monthly change, the lake area was relatively bigger from March to May in 2001; from May 2001 to November 2001, the lake area reduced continuously and the change rate was -4.4%; from November 2001 to March 2002, the lake area increased again and the change rate was +2.2%; from March 2002 to November 2002, the lake area reduced lastly and the change rate was -4.1%.

Download Here