七里海泻湖湿地演变过程及其生态环境效应分析

The Evolution Process and Analysis on Eco-environmental Effect of the Qilihai Lagoon Wetland

以河北省秦皇岛市昌黎县七里海泻湖湿地为研究区,选取1919～2005年间的4幅地形图和1987年以来的10景landsat TM(ETM)遥感影像为数据源,运用遥感和地理信息系统技术,研究了七里海泻湖湿地近百年的时空演变过程,分析了泻湖湿地演变的影响因素与生态环境效应。结果表明,近百年来,七里海泻湖面积发生明显变化,由1919年的711.1hm2缩减为2005年的279.1hm2;1919年泻湖周边沼泽湿地面积为2263.3hm2,2005年泻湖周边的沼泽湿地已经基本消失;1956年以前,泻湖湿地以自然演变为主,主要受雨量充沛、入湖河流径流量丰富的影响,泻湖水面面积呈逐年增加趋势,1956以后,受流域开发治理工程、围垦和水产养殖等人类活动的影响,泻湖及周边湿地水动力条件发生改变,泻湖周边天然湿地逐渐为人工湿地所代替,泻湖水面面积减小,淤积加重,湿地生态系统受到极大干扰,呈现出生物多样性降低、景观单一化、湿地效应减弱等生态环境恶化的特征。

Taking the topographic maps and remote sensing images during 1919 to 2005 as the data source and using remote sensing and geographic information system technology, the spatial and temporal changes of the Qilihai lagoon wetland in Changli, Qinhuangdao, Hebei Province were studied in this paper over the past 87 years. The factors, which impact on the evolution of lagoon wetland and eco - environment, were analyzed in accordance with historical statistics information and observation data. The results showed that the area of Qilihai lagoon changed remarkably which deflects from 711.1 ha in 1919 to 279.1 ha in 2005 during the past 87 years. The evolution of the Qilihai lagoon wetland has mainly gone through 3 stages in accordance with different dominant factors. During the period of naatural evolution from 1919 to 1956, the lagoon wetland took nature evolution mainly and the lagoon area increased from 711.1 ha in 1919 to 984.3 ha in 1956. The lagoon area continued to increase up to 1 282.3 ha in 1969. However, because of construction of bastardies and tidal barrier from 1969 to 1979, the tidal channel became narrow, and hydrodynamic conditions had remarkably shifted. Consequently the water area was bind by 817.9 ha and the mud and silt have been continuously deposited in the lake basin. The degeneration phenomenon occurred in the aquatic environment. During the period of impact caused by cofferdam and aquaculture from 1979 to 2005, a large scale cultivated activities caused a sharply reduction of lagoon area which was down to 279.1 ha under the backdrop of construction of the dam and tidal barrier. The natural wetlands surrounding the lagoon which areas was 2 263.3 ha in 1919 have basically disappeared until 2005 and gradually replaced by artificial wetlands. The water quality was deteriorated due to pollution and envi- ronmental degradation. The area of natural wetland around the Qilihai lagoon decreased, which resulted in the habitats of various wildlife were compressed massively and wildlife communities were replaced by artificial biotic communities. So the wetland biodiversity has been reduction. The entire ecosystem becomes the high vulnerable ecosystem. The deflation of lagoon area and aggravation of lake basin siltation caused the functions of flood control storage, runoff equalization and climate adjustment to be weaken greatly. The people pollutant, solid waste and aquaculture wastewater produced by large -scale reclamation as well as oily sewage created by fishing boat in new aperture fishing port have great influence on the lagoon water quality. The ecological environment of the Qilihai lagoon wetland has been worsening seriously day by day.