洞庭湖洲滩地年淹水天数和面积变化

研究了洞庭湖洲滩地年淹水天数和面积变化。利用洞庭湖代表性水文站1952~2000年的逐日水位资料，分析了洞庭湖洲滩地的多年平均淹水时间（天数）。结合20世纪70年代和90年代不同水位时相卫星图像的解译数据，通过插入法和相关分析，得出了20世纪70和90年代不同淹水天数的洲滩地面积。结果表明，区内不同区域变化各异，东洞庭湖不同淹水天数的洲滩地均减少，南洞庭湖中位的洲滩地增加，但高位和低位洲滩地减少，西洞庭湖不同淹水天数的洲滩地均增加。表明东洞庭湖在70~90年代发生了逆向演替，南洞庭湖以正向演替为主，西洞庭湖发生了正向演替。为此，提出中低位洲滩地不宜发展杨树，获、芦生产的重点应该逐步地由东洞庭湖向西、南洞庭湖转移。

VARIATIONS OF FLOODED DAYS AND AREAS OF BEACH WETLANDS IN DONGTING LAKE

The paper discussed flooded days and areas of beach wetlands in Dongting Lake.To identify the flooded days in a year in the beach wetland，daily data of water level in Dongting Lake during 1952~2000 were applied.Variations of different flooded days in a year and area of the beach wetland were identified by using data from TM satellite picture with assistance of correlation analysis and interpolation method.Reduction of flooded days in a year in the beach wetland in east Dongting Lake during 1990’s indicated that it had shown reverse succession.The area of beach wetland flooded more than 100 days in a year had reduced in south Dongting Lake；however，the area of beach wetland flooded less than 100 days had enlarged.These indicated that the positive succession is the essential case in south Dongting Lake.Enlarging of beach wetland of different flooded day in a year in west Dongting Lake indicated that it had taken the place for positive succession.Correspondingly，it was proposed that it is not suitable to plant in the low beach wetland of Dongting Lake，and reed production should be shifted gradually to the west and south parts of Dongting Lake.