基于全球地表水数据的长沙市湿地景观动态变化研究

Dynamic change of wetland landscape in Changsha based on JRC global surface water data

【目的】探究长沙市1999—2019年湿地景观的时空演变规律,综合分析长沙市湿地景观格局的动态变化特征,以及自然、人为因素对湿地景观格局的影响机制,为长沙市湿地资源的保护与合理利用提供理论依据。【方法】基于全球地表水数据(GSWD),结合气象、水文等数据,采用湿地分布信息提取、湿地类型划分和景观格局指数的方法,针对湿地季节性和波动变化特征,对长沙市1999—2019年湿地景观格局的动态演变情况进行长期且连续的监测,分析其长时间尺度的演变趋势以及短期的波动变化特征。【结果】(1)1999年以来,长沙市湿地面积持续增加,其中,永久性河流是长沙市的主要湿地类型。2007—2009年,长沙市湿地景观发生了较大的变化,主要表现为2008年前永久性河流、湖泊分别向季节性河流、湖泊转化,2008年后出现逆转。2017年以前,长沙市湿地景观格局破碎化程度不断加剧,2017年之后开始逐渐恢复。(2)在自然因素中,长沙市湿地面积受降水和湘江径流量影响较大;在人为因素中,人口的增加和粗犷的社会经济发展模式,会间接导致景观格局破碎化加剧,但政府政策和措施对湿地修复具有强制性作用。【结论】基于全球地表水数据提取湿地信息具有可行性;长沙市湿地面积持续增加,永久性河流及其周边是主要湿地类型。研究结果可为长沙市湿地资源的保护与合理利用提供重要参考。

[Objective]The objectives of this study were to explore the temporal and spatial evolutions of wetland landscape in Changsha from 1999 to 2019,to comprehensively analyze the dynamic-change characteristics of wetland-landscape patterns in Changsha in the same period,and to explore the influence mechanism of natural and human factors on wetland-landscape patterns,so as to provide an important theoretical basis for the protection and rational utilization of wetlands in Changsha.[Method]Based on global surface water data(GSWD),combined with meteorological and hydrological data,this paper adopted the methods of wetland distribution information extraction,wetland type classification and landscape pattern index,aiming to achieve long-term and continuous monitoring of the dynamic evolution of annual wetland-landscape patterns in Changsha City from 1999 to 2019 based on the seasonal and fluctuating characteristics of wetlands.In addition,we analyzed the evolution trend of its long time scale,as well as the short-term fluctuation change characteristics.[Result](1)Since 1999,the wetland area in Changsha has been overall increase,with permanent river being the main wetland type.From 2007 to 2009,there was a large fluctuation in wetland landscape,as represented by the transformation of permanent rivers and lakes to seasonal rivers and lakes,respectively,in the early stage,and by the reversal of fragmentation after 2008.The fragmentation degree of wetland-landscape pattern in Changsha continuously intensified until 2017 and later began to gradually recover.(2)The wetland-landscape pattern in Changsha was greatly affected by the natural factors such as precipitation and runoff from the Xiangjiang River and extreme freezing disasters that led to large fluctuations of the wetland-landscape pattern.The wetland landscape pattern in Changsha was also affected by human factors such as growing population and urban expansion that may lead to the intensification,but government policies and measures had a positive effect on wetland restoration.[Conclusion]It was feasible to use GSWD to extract wetland information.The wetland area in Changsha had continued to grow,among which permanent river was the main wetland type.The results from this study could provide important scientific references for the protection and rational utilization of wetlands in Changsha.