Abstract:

According to historical literatures,maps,water and sediment data,water quality monitoring data from 1986 to 2010,13 indicators including external and environmental indicators,hydrodynamic conditions and biological indicators were selected to evaluate the healthy condition of the lake ecosystem during the typical years by Projection Pursuit method based on Genetic Algorithm in the Dongting Lake. The results show as follows. From 1986 to 2010,the projection value of ecosystem health in the Dongting Lake showed a tendency of  “wavy descend”. The highest value was in 1991(1.7264), the lowest healthy membership grade was in 2006(1625 8),and in 2010 the projection value began to rise again(1.679 0). The South Dongting Lake had a relatively good health status,then followed by West Dongting Lake, and the East Dongting Lake was the worst one.It illustrated that water dynamic conditions,biodiversity and water quality have been changed a lot under the effect of the reclamation of lakes,returning farmland to lake and the Three Gorges Reservoir,but it exists some differences in different lakes