基于长期水文变化的苏北高邮湖生态水位及保障程度

湖泊生态水位是维持湖泊生态系统结构和功能完整性、维持生物多样性的最低水位,研究湖泊生态水位过程对湖区动、植物栖息地保护和湖泊水资源管理具有重要意义.利用高邮湖1953-2013年日水位资料进行生态水位计算分析,采用M-K法和滑动T法对1953-2013年年均水位进行突变检验,分析高邮湖1953-1992年来水文变化规律,结合年保证率法和年内展布法得到高邮湖逐月最低生态水位过程,并计算出高、低水位发生时间及历时,在此基础上对其1993-2013年生态水位保障程度进行研究.主要结论有:(1)高邮湖年均水位过程突变发生在1997年;(2)高邮湖高水位时期(7-10月)的最低生态水位为5.8 m,水位高于5.9 m的天数要达到111 d左右;低水位时期(12-次年3月)的最低生态水位为5.1 m,水位低于5.3 m的天数要达到96 d左右;其余月份最低生态水位为5.2 m;(3)高邮湖生态水位年内保障程度最低发生在7月,为60.83%,年际保障程度1994年和2001年最低,分别为49.59%和50.41%,低水位天数得不到保障.

Determination of the ecological water-level and assuring degree in the Lake Gaoyou, northern Jiangsu with long-term hydrological alteration

The ecological water level is the lowest water level to maintain the integrity and variety of a lake ecosystem. For the protection of the biological habitats and the management of water resources, the study in an ecological water level is meaningful. Based on daily water level data of Lake Gaoyou, northern Jiangsu Province, from 1953 to 2013, the ecological water level data is calculated and treated. The mutation tests are carried using Mann-Kendall method and moving T-test method. The water level regulation in 1953-1992 is analyzed. The monthly progress of the lowest ecological level is also deducted using the annual guaranteed frequency method and dynamic calculation method. The starting time and duration of high/low water levels of Lake Gaoyou are calculated accordingly. The key conclusions are as follows:(1) The mutation point occurred in 1997. (2) The lowest ecological water level of high water level period (from July to October) is 5.8 m, and the time that the water level is higher than 5.9 m needs to be 111 days; the lowest ecological water level of low water level period (from December to next March) is 5.1 m, and the time that the water level is lower than 5.3 m needs to be 96 days; the lowest ecological water level is 5.2 m for the other months. (3) The lowest assuring degree of the ecological water level occurs in July of the year, being 60.83%. The lowest assuring degree in 1993-2013 occurs in 1994, being 49.59%. The days of low water levels are not secured.