基于遥感影像的黄河三角洲湿地景观演变及驱动因素分析

为揭示1973-2013年黄河三角洲湿地景观演变情况及其驱动因素,更好地服务于区域湿地生态保护和恢复,利用1973-2013年9期Landsat卫星影像,构建了黄河三角洲湿地景观数据库。阐述了黄河三角洲湿地景观组成现状、分布规律和阶段特征,并结合黄河入海水沙及社会经济数据,探讨了其驱动力。研究表明:1)黄河三角洲湿地以自然湿地为主,近40 a来湿地总面积呈下降趋势,且以自然湿地向人工湿地和非湿地的转换为主要特征,湿地景观破碎化趋势严重;2)黄河三角洲湿地景观面积的整体下降趋势与黄河入海水沙的整体减少有较好的函数关系,且以输沙量对自然湿地景观,尤其是咸水湿地景观变化趋势的影响更强,径流量则对淡水湿地景观的影响更为突出。3)黄河三角洲湿地景观面积变化亦具有阶段性特征,这是由于黄河来水来沙量的显著周期性变化,叠加上持续扩大的人类活动影响所致。该研究分析了黄河三角洲湿地景观格局演变规律,并定性探讨了主要驱动因素,相关结论对区域湿地保护和恢复具有一定参考意义。

Analysis of wetland landscape evaluation and its driving factors in Yellow River Delta based on remote sensing image

As one of the most active regions in the world, the Yellow River Delta has a large-area wetland which plays a significant role in balancing the regional eco-environment. However, in the past decades, increasingly severe natural and human environment have formed great threat to the Yellow River Delta wetland. Researches are urged to make clear what exactly has changed and which factors exactly result in it in order to put forward the measures of instructions on regional wetland protection. Therefore, a wetland landscape database that contained 9 land use maps of the Yellow River Delta in the year 1973, 1979, 1985,1992, 1995, 2000, 2005, 2010 and 2013 was constructed with artificial visual interpretation as method and Landsat-MSS/TM/ETM/OLI satellite images as data source. Combined with the Yellow River runoff and sediment data, socioeconomic data, the Yellow River Delta wetland evolution and its driving factors were analyzed. Researches showed that:1) Natural wetland was the primary wetland of the Yellow River Delta, among which saltwater wetlands accounted for the larger proportion. However, different natural wetland types had different distribution feature: saltwater wetlands had an evolution sequence from sea to land, while freshwater wetland had an evolution sequence by the distance to the Yellow River. Active and widely distributed, the tidal creek played good corridor function, and dominated the landscape distribution and evolution. 2) The wetland area of the Yellow River Delta experienced an overall decline during 1973-2013, and showed an overall fragmentation trend, accompanied with large scale natural wetland converting to artificial wetland and non-wetland. 3) Changes of wetland area of the Yellow River Delta also presented stage characteristics, mainly due to the superimposed effect of the significant periodic changes of the Yellow River runoff and sediment and the increasingly severe human influence. 4) There was a function relationship between the change of wetland area and the Yellow River runoff and sediment, which was especially close between saltwater wetlands and sediment, and between freshwater wetlands and runoff. However, more improvement should be made in further study as follows: 1) Main driving factors were discussed just based on qualitative analysis, and a more quantitative method needs to be used to quantify the driving factors in the process of wetland landscape evolution, which will provide the better guidance for regional wetland protection and restoration. 2) Only Lijin hydrometric station data were used in this study, which failed to quantify the distribution of water and sediment in space, and thus, the relationship between wetland landscape evolution and water-sediment change needs to be studied more clearly. At the same time, ocean and land interaction is another important factor which should be taken into account in the future. 3) Besides, as a typical coastal wetland landscape, tidal creek plays a significant role in regional wetland evolution, but due to space limitation, its effects were not presented in this article.