| 其他摘要 | The Yellow River Delta (YRD) wetland is a typical coastal wetland in the warm temperate zone of China. Massive sediment is transported from the Loess Plateau to the YRD each year by the Yellow River which results in the new-born protogenetic wetland. The special natural conditions of the YRD is suitable for wetland research. Under the background of global climate change, the YRD wetland plays an important role in the regional development. The “Yellow River Delta High-Efficiency Ecolonomic Zone” Plan and “Shandong Peninsula Blue Economic Zone” plan were implemented in the YRD since 2006 which promoted the YRD to be an interactional hotzone of economy and environment. How to maintain the balance of development and environment? Wetland is the key element in regard to this issue. It is important to understand the evolution process, land change stages, land change prediction and driving factors of land changes of the YRD wetland. In this study, we used the remote sensing, global positioning system and geographical information system technologies to study the land change processes and driving mechanism of coastal wetlands in the YRD from 1976 to 2013. As supplement, field investigation, model simulation and laboratory experiment were also adopted in our study. The main results were as follows: 1) The length of coastline of in the YRD increased by 10% from 1976. The proportion of artificial coastline increased from 27.96% to 84.65 %; 2) There were three evolution stages of the YRD from 1976. The rapid growth stage from 1976 to 1986, stagnant stage from 1986 to 2000 and the slow growth stage from 2000 to 2013. The delta area had a growth of 699.45 km2 during the past 37 years which indicated a growth of 18.90 km2 per year; 3) Factors influencing the evolution of the YRD included the land-ocean interaction, runoff of the Yellow River and anthropogenic activities; 4) The distribution, composition and structure of wetland had significant changes since 1991. The area of natural wetlands declined from 1997.20 km2 to 1485.91 km2 during 22 years (1991-2013), with an average decrease of 23.24 km2 per year. The area of natural wetlands increased from 112.22 km2 to 560.21 km2 during the 22 years, with an increase of 20.36 km2 per year. Sub-classes of wetlands also showed different change results; 5) Marsh, bush wetland, swamp, slat marsh, tidal flats, soak, pond, paddy field and salt pon contributed to the main changes of wetlands; 6) Wetland degradation is common phenomenon in the YRD. From 1999 to 2004 and from 2004 to 2009, about 40% wetland in the YRD suffered the worst degradation, with a loss area of close to 700 km2 for each stage; 7) The wetland in the YRD was facing some ecological crisis. Both areas of the natural and artificial wetlands might decrease a lot from 2013 to 2021 by change simulation; and 8) Both natural and artificial factors promoted the land changes of wetland in the YRD. Seawater, runoff of the Yellow River, roads, land use type, artificial facilities, oil exploitation, policy and regulations were the most important factors that influencing wetland. The concept model of driving mechanism of wetlands in the YRD was finally built. Our results are expected to contribute to the sustainable development of wetlands in the YRD.
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