1975年—2018年白洋淀湿地变化分析

白洋淀湿地生态功能重要、战略地位特殊，研究其时空变化规律具有重要意义。本文基于1975年—2018年间10期Landsat卫星遥感影像，辅以2017年—2018年高分二号（GF-2）卫星遥感影像，在野外考察湿地类型及其覆被特征基础上，人机交互解译获取各期土地利用/覆被分类图，从面积变化、类型转化、景观格局变化方面分析了近43年白洋淀湿地变化时空特征，讨论了影响分析结果的不确定性因素以及湿地变化成因。结果表明：1975年—2018年白洋淀湿地面积总体呈减少趋势，净变化-68.20 km²（-24.83%）。其中，1975年—1990年湿地面积波动性小、基本稳定，1990年—2011年湿地面积持续性减少，2011年—2018年湿地面积呈现增加趋势。湿地与非湿地类型相互转换区域主要分布于淀区南部、西部、北部的水体—水生植物—耕地—建设用地过渡区域。近43年白洋淀湿地景观趋于破碎、复杂和异质。遥感影像选取月份、年份，以及土地利用/覆被分类体系、分类方法，是影响分析结果的主要不确定性因素。气候、水文等自然因素变化，叠加工农业及城镇生活用水、上游水利工程蓄水、地下水开采等人为因素变化，是白洋淀湿地面积减少、趋于干化的成因。

Analysis of changes of Baiyangdian wetland from 1975 to 2018 based on remote sensing

Baiyangdian Wetland is located in Xiong''an New Area, with important ecological functions and special strategic position. For a long time, under the combined effects of human activities and climate change, the Baiyangdian Wetland has gradually shrunk and even dried up. It is of great significance to further study the carrying capacity of ecological and environmental of the Xiong''an New Area by understanding the change characteristics and ecological functions of the Baiyangdian Wetland ecosystem. Currently remote sensing based analysis of changes of this region has insufficient in research periods, classification system and information interpretation of land use/land cover of wetland.
This work studied spatiotemporal characteristics of changes of Baiyangdian Wetland from 1975 to 2018. Images of Landsat MSS/TM/ETM+/OLI during 1975-2018 and GF-2 PMS in 2017 and 2018 were acquired to analyze land use/land cover change. First, image interpretation symbol were built based on field survey of wetland types and their image features. Then, all images in ten periods were interpreted visually and land use/land cover were mapped out during 1975-2018. Last, we analyzed spatiotemporal characteristics of changes of Baiyangdian Wetland from changes of areas, types and landscape patterns.
Results showed that areas of the Baiyangdian Wetland decreased 68.20 km² (24.83%) from 1975 to 2018. Different characteristics were at different time periods. The wetland area was basically stable from 1975 to 1990, but decreased continuously from 1990 to 2011. In the period of 2011-2018 wetland area showed an increasing trend. The inter-transformation areas between types of wetland and non-wetland were mainly distributed in the transition region of water-aquatic plants-cultivated land-construction land, in the southern, western and northern parts of the Baiyangdian Wetland. In the past 43 years, the landscape pattern of Baiyangdian Wetland has become fragmented, complex and heterogeneous.
Main uncertain factors affecting the analysis results include acquired time, such as month and year, of satellite images, classification systems and methods of land use/land cover. Changes in natural factors, such as climate, hydrology, as well as in human factors, such as water consumption from industrial, agricultural and urban, water resources projects in headwaters of baiyangdian basin, and groundwater exploitation, are the causes of the reduction and drying of the Baiyangdian Wetland.