基于形态结构特征的洞庭湖湖泊健康评价

湖泊形态结构特征与湖泊健康水平密切相关,是评价湖泊生态系统、服务功能是否健康的基础。以历史文献、图件及1986—2010年水沙实测数据等资料为依据,选取洲滩出露频率、水动力条件和几何形态等3类共8个湖泊形态结构特征指标,采用突变级数法对典型年洞庭湖湖泊健康状况进行评价。结果表明:(1)东洞庭湖湖泊健康状况相对较好(隶属度平均值为0.7486),但波动较大(0.6775—0.7965);南洞庭湖次之(0.7311);西洞庭湖最差(0.7269),其健康相对隶属度波动最小(0.7026—0.7487);(2)近20a来,洞庭湖湖泊健康状况呈现"先恶化、后改善"的趋势。1998年其健康隶属度最低(0.6912),2004年值最高(0.7711),其余典型年的值介于二者之间。这充分说明"4350"工程实施、三峡水库蓄水运行等有效地改善了洞庭湖湖泊形态结构,使其朝健康方向发展。

Health evaluation of Dongting Lake based on morphological characters

The lake's morphological characters is closely related to the functions of lake ecosystem. It is fundamental to evaluate service function and healthy conditions. According to historical literatures, maps, water and sediment data from 1986 to 2010, 8 indicators of morphological characters including the exposed frequency of bottomland, hydrodynamic conditions and geometry form of the lake were selected to evaluate the healthy condition of the lake ecosystem during the typical years by catastrophe progression method. It showed that: (1) The East Dongting Lake has a relatively good health status (the average membership grade was 0.7486), but with great fluctuations (0.6775-0.7965); then followed by South Dongting Lake, (0.7311); the West Dongting Lake (0.7269) was the worst one with a minimum fluctuation of health relative membership degree (0.7026-0.7487);(2) In the last 20 years, the health standard of Dongting Lake Basin had showed a tendency of " worse at the beginning then improved". It had the lowest healthy membership grade in 1998(0.6912), and the highest value was in 2004(0.7711), the values of the other typical years were in the middle, which might be the result of the strong support from both the implementation of "4350" project and Three Gorges dam.