Global warming and rising sea level have been observed to exert great impacts on China’s coast in the past century, includingincreased coastal erosion, degraded coastal ecosystems, exacerbated saltwater intrusion, and enhanced storm surges. The impacts ofclimate change and the adjustments of coastal systems are significantly site specific, resulting from local differences in climate change,coastal physiographic and ecological conditions, and resilience of coastal systems. Anthropogenic activities also exert increasing influenceson coastal systems. Societal vulnerabilities to climate change are greatly influenced by their adaptive capacities and selective adjustment,which are greatly determined by local socioeconomic conditions, so they are also highly localized. Coastal systems do not behavelinearly to climate change. The projected increasing global warming and accelerating sea level rise will undoubtedly impose morethreats to coastal systems. However, it is still difficult to determine the coastal socio-ecological thresholds to climate change without fullunderstandings of coastal physical and biological processes, and adaptation responses of coastal ecosystems and human societies.

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.