近40年来白洋淀湿地土地覆被变化分析

白洋淀是华北平原上现存最大的天然湖泊,是典型的内陆湿地。最近40年,白洋淀湿地出现了水面萎缩、生态功能急剧退化、生物多样性减小和水体污染严重等生态环境问题。本文利用1964年CORONA侦察卫星影像、1974年和1983年Landsat MSS影像和2002年ETM+影像,对白洋淀湿地的土地覆被变化及其驱动力做了详细分析。结果表明,湿地面积呈减少趋势:1964年为407.3km2,2002年缩减到274.63km²。湿地水面起伏变化大,1964年水面较宽,为346.75km²;到1974的10年间,减少到94.65km²,1983年和2002年水面继续变窄,水面面积分别为67.27km²和46.86km²。引起湿地土地覆被变化的原因包括降雨量的减少、蒸发量的增大、城市发展用水增大、不合理土地利用开发和上游水库、引水工程修筑等。

Land Cover Change in Baiyangdian Wetland

Baiyangdian is the largest natural lake and the typical inland wetlands in the North China Plain.In recent 40 years,Baiyangdian wetland is facing serious environmental problems,such as water shrinking,ecological function degradation,biodiversity reduction,and water pollution.In this paper,by using the CORONA spy satellite image in 1964,Landsat MSS images in 1974 and 1983,ETM＋ image in 2002,the land cover change and driving forces of Baiyangdian was analyzed.The eCognition 5.0 was used to classify the remote sensing images of the study area,and the spatial analysis superimposed tools in ArcGIS 9.0 was used to obtain the land cover conversion data in different years.The result indicated that the area of the Baiyangdian wetland is decreasing in the study period.The area in 1964 is 407.3km2,and 274.63km2 in 2002.Furthermore,great change happened in the water area.In 1964,the water area is larger,with the value of 346.75km2.In 1974,the water area decreased to 94.65km2.In 1983 and 2002,the water area is smaller,with the value of 67.27 and 46.86km2 respectively.The main factor that causes the land cover change is the variation of water supply.There are two main reasons to impact the water supply of the study area.One is climate change,including the decreased precipitation and the increased evaporation.The other one is human activities,such as water consumption for urban development,land use change,the construction of reservoirs and water transfer projects.This paper applied the early CORONA spy satellite images to Baiyangdian wetland land-cover change analysis,solved the problem of lacking in data of early time period in the region.It made the research time back up to 1960s.Furthermore,the multi-temporal satellite remote sensing data used in the study improved the temporal resolution of land cover monitoring,and provided basic data for performance of regional land-cover change analysis.