长江口外羽状锋的屏障效应及其对水下三角洲塑造的影响

河口锋在大多数河口地区均有出现,它在河口过程中有着重要作用。国外ＢｏｗｍａｎＭ．Ｊ．１９７８年对河口锋的动力学问题作过一些研究 ,国内有学者１９９３年和１９８９年对长江口河口锋的特征以及对泥沙运移的作用作了阐述 ,但由于锋的多尺度和瞬时演变的复杂性,加之测试手段的局限 ,至今尚未取得成熟的理论 ,对锋的研究目仍处于初级阶段。近年来在长江口水文观测和河口锋大面调查期间 ,多次发现清、混体交汇的羽状锋 ,经进一步研究还发现羽状锋带常位于水下三角洲前部部位上 ,而且其走向也常和水下三角洲前缘线基本一致。由此引起思考 :…

THE BARRIER EFFECT OF PLUME FRONT ON THE SUBMERGED DELTA DEVELOPMENT OF YANGTZE RIVER ESTUARY

Based on data obtained from the survey of the Yangtze River Estuarine front, a detailed analysis of the frontal surface structure, position, intensity and seasonal variations is presented. From the frontal surface structure and water densities of both sides of the front, a formula of frontal surface barrier force is deduced based on the hydrostatic principle, which suggests the barrier effects of estuarine plume front. Furthermore, the correlation analysis between barrier effects and underwater topography indicates the plume front effects on the submerged delta development. That is, the average frontal surface position prevents the submerged delta from further extending eastward, the front movement with flood and ebb causes the submerged delta to slant eastward gently, and the seasonal variations of frontal intensity restricts the submerged delta cycle of summer deposition/winter erosion.