长江与尼罗河河口区地貌环境演化和人类活动对比研究

Numerous boreholes and radiocarbon-dated late-Quaternary stratigraphy obtained from the Yangtze and Nile delta plain helps extensively understand the coastal environmental evolution through time-period defined. The results of the present study primarily include: 1) Holocene delta at both geographic sectors began to form at ca. 7000 yrs BP., which is the response to deceleration in eustatic sea-level rise; 2) the sea-level rise at the Yangtze and Nile coast demonstrates an un-coeval fluctuations that can be attributed to the differences of local subsidence; 3) sedimentary facies assemblage at the both delta system shows similarity, but grain-size goes far beyond the comparable level, characterized by the silt-dominated sedimentary setting in the Yangtze, and medium and fine sands in the Nile. The former reflects the tidal accumulation along the coast and the latter illustrates the longshore-driven erosive processes; 4) late Quaternary stiff muds widely found in the delta plain, which were defined as the fluvio-lacustrine deposits largely afftected by the paleoclimate fluctuations of temperate Yangtze and hot-dry Nile pattern, and 5) human activity at the both delta plain results in considerably environmental deterioration, which is featured chiefly by the lake shrunk and coastal erosion at the Nile and drainage network vanishing and associated floods in the Yangtze. The result of the present study provides insight into the late Quaternary delta evolution on global scale.

利用大量钻孔和分析资料，进行长江和尼罗河三角洲全新世河口区地貌环境演化的对比研究，重点剖析波浪型和潮流型河口地貌演化特点；探索气候、海平面波动的共振或异振特点，及河口地貌在时空演变上的响应；阐明河口区沉积、沉降速率及其控制因素，并与海平面波动关系；分析人类活动特点及对河口地貌作用；旨在为全球河口环境演变提供科学依据。.