简要综述了中国开敞型潮坪的分布与特征，总结了多年来在开敞型潮坪所做的野外观测结果，包括不同时司尺度沉降板观测分析潮汐层偶的生成和保存，插桩观测季节性潮滩冲淤和研究砂、泥质单层的形成与保存结果表明，潮流和波浪侵蚀造成开敞型潮坪潮汐纹层的保存率极低，连续性差季节性强风浪和平静天气交替形成的小型层序，其中砂、泥质纹层厚度的变化与大小潮旋回所形成的沉积序列类似，但二者的成因不同，所代表的时司尺度差别较大因此，在进行高分辨率古潮汐环境研究时需严格分析潮汐沉积的连续性

长江三角洲人地相互作用经历了三个大的发展阶段，在此过程中人对环境的影响不断增强。早期人类的生活和生产方式主要依附于三角洲的自然环境，人们的生产活动场所也受制于三角洲发育的影响。之后人们逐渐采取适应自然变化的措施，力争能与自然协调发展。随着人口增长，经济发展、技术进步，过度的人类活动已使长江三角洲生态环境不断恶化。主要的问题包括地面沉降、洪涝灾害、污染、盐水入侵和海岸侵蚀等，三角洲已经成为全球变化的主要脆弱区之一。由于影响长江三角洲环境的因素众多，关系复杂，以及人类的主动适应能力，目前难以确定三角洲系统的气候变化阈值，即超过它系统将发生不可逆转的衰退。

三峡大坝建成之后，大量泥沙滞留于库区，出库泥沙量减少，坝下河床冲刷而提供相当数量的泥沙，支流湖泊供沙也发生变化，这将使进入河口地区的泥沙有所减少。三峡大坝以上长江干流和支流建设新的大坝，南水北调、封山育林、退耕还林以及减少水土流失都将进一步减少长江进入河口地区的泥沙。由此估计，三峡大坝建成后的百年内长江输入河口地区的泥沙约为2 0×108。2 5×108∥a；冰后期长江三角洲形成和发育期司的长江年均输沙量为l 84×108。2 28×108t。二者的数值相当接近，然而与近50年的观测（4 33×108∥a）相差甚远，长江流域的气候变化和人类活动可能是造成这一现象的原因。文章着重说明中国和长江上游人口的增长、种植作物的改变可能是水土流失、长江泥沙量增长的主要原因。

在过去的一个世纪，中国海岸已明显观测到气候变暖和海平面上升所造成的危害。气候变化对中国海岸带的影响和海岸系统对气候变化的适应性具有明显的区域性差异。海岸自然条件复杂，海岸不同生态环境的自修复能力各异。人类活动对海岸带的影响巨大，在适应气候变化方面具有明显的能动性，适应能力受社会经济发展水平的制约，从而具有明显的区域特征。海岸系统与气候变化之间并不是简单的线性关系。未来气候变暖和海平面加速上升无疑将加大对海岸带的影响，但目前尚难以确定海岸生态系统的气候变化阈值。

Four sediment-rich incised-valley systems in China, which underlie the Luanhe fan delta, the Changjiang delta, the Qiantangjiangestuary, and the Zhujiang delta, are examined based on over 800 drill cores. These four systems are of different shapes and sizes, and arelocated in different tectonic zones with different tide regimes ranging from microtidal to macrotidal. Because of the abundant fluvialsediment supply and relative dominance of river forcing, sediments in the modern Qiantangjiang and paleo-Changjiang estuaries displaya fining-seaward trend. This is different from the classical estuarine facies model of coarse bay-head delta, fine central basin, and coarsebay-mouth deposits. The abundant sediment supply also results in the presence of relatively thick transgressive successions in the overallincised-valley fill. The transgressive succession constitutes more than 50% of the total strata thickness and approximately 60–70% of thetotal sediment volume within the valley. The river-channel facies in the transgressive succession was formed by retrogressive aggradationduring postglacial sea-level rise. Retrogressive aggradation extends far inland beyond the reach of flood-tidal currents, and, therefore, nomarine signatures were found at the lower portion of the incised-valley fill. The regressive succession in the incised-valley systems consistsof fluvial facies or tidal facies and deltaic facies, and was developed as the estuary filled and evolved into a progradational delta. The tidedominatedfacies tends to be developed in the apical areas of funnel-shaped estuaries, such as the modern Qiantangjiang and paleo-Changjiang estuaries.Four generalized facies successions (FS-I, FS-II, FS-III, and FS-IV) are recognized within the valley fill. An idealized schematic incisedvalleyfill contains FS-I at the coastline region, FS-II and FS-III in the middle, and FS-IV at the apex area of the delta/estuary, reflecting adecreasing marine influence and increasing terrestrial contributions. The preservation of multiple incised-valley-fill sequences iscontrolled by the different regional tectonic characteristics. Vertically superimposed valleys are preserved beneath the Changjiang delta,whereas the Luanhe fan delta is characterized by lateral juxtaposition of valley as a result of channel switching.