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On 23 August 2017 a Category 3 hurricane, Typhoon Hato, struck southern China. Among the hardest hit cities, Macau experienced the worst flooding since 1925. In this paper, we present a high-resolution survey map recording inundation depths and distances at 278 sites in Macau. We show that one-half of the Macau Peninsula was inundated, with the extent largely confined by the hilly topography. The Inner Harbor area suffered the most, with a maximum inundation depth of 3.1 m at the coast. Using a combination of numerical models, we simulate and reproduce this typhoon and storm surge event. We further investigate the effects of tidal level and sea level rise on coastal inundations in Macau during the landfall of a "Hato-like" event. [ABSTRACT FROM AUTHOR]

Asian deltas are densely populated and richly bio-diversified regions with significant social, economic, ecological and environmental importance across the globe. These low-lying and fertile floodplains support substantial food production. Because of sediment supply reductions, sea-level rising, subsidence, and frequent storm surges, many deltas are rapidly sinking and shrinking, which will threaten survival of millions of populations. It's of great significance to monitor the delta morphological evolution and understand the relationship between their shoreline migrations and sediment supplies. However, quantifying the delta morphological changes is challenging due to its nature of high dynamics. In this study, we developed a methodology integrated by a time-series algorithm of water frequency and a spatial analysis to track the morphological changes of 11 major Asian deltas from 1986 to 2018.The results show that the deltas of Yellow, Yangtze, Pearl, Red, Mekong, Ganges-Brahmaputra, and Chao Phraya have experienced a net land gain at the total of 1829.3 km2, with China's three major deltas accounting for 73 percent of all. The deltas of Mahanadi, Irrawaddy, Indus, and Godavari-Krishna have undergone a net land loss at the total of 295.1 km2, of which the Indus River Delta accounted for 65 percent. Most of the shorelines in the Yangtze River Delta were constantly advancing seaward at a rate of over 30 m/year, whereas, many ones in the rest of Asian deltas were significantly being eroded at a rate of over 20 m/year. These changes in delta morphology are closely related to sediment supplies and management policies. These results also suggest that rational wetland reclamation with auxiliary projects of ecological restoration can enhance the deltaic ability of sustainable development. [ABSTRACT FROM AUTHOR]

Understanding ancient climate changes is hampered by the inability to disentangle trends in continental ice volume from records of relative sea-level change. As a unique coastal deposit in tropical and subtropical regions, beachrock has been proved to be reliable for constraining the glacial meltwater signal and thus the total volume of land-based ice in Quaternary. However, beachrock is rarely recognized in the fossil record due to (a) the two-dimensional distribution of beach deposits, as opposed, for example, to extended platform sediments, and (b) the fact that specific environmental conditions are required in order to lithify sediments directly on the beach. By combining the stratigraphic architecture with petrography of characteristic carbonate cements, we demonstrate the first known occurrence of Ordovician beachrock in the Tarim Block, northwestern China. According to biostratigraphic data, a middle Katian (Upper Ordovician) palaeokarst surface is capped by carbonate conglomerate beachrock and this is suggesting a significant relative sea-level rise in late Katian. The beachrock can be correlated with widespread subaerial exposure surfaces and a pronounced stratigraphic gap within the Katian in northwestern Tarim. We suggest that the beachrock ‘fingerprinted’ a strong melt-water pulse in high latitudes after a short-lived Katian glaciation, which has not received much attention in scientific papers so far. [ABSTRACT FROM AUTHOR]

The Hirnantian period, making the end of the Ordovician with significant mass extinctions and large ice‐sheets, is a critical interval for studying paleoclimate variations. This research represents the first cyclostratigraphic study of this period, utilizing high‐resolution (1 mm sampling rate) geochemical data from the ∼7‐m thick SH‐1 drill core, capturing the latest Ordovician glaciation. Our analysis identifies the presence of Milankovitch cycles with periods of 17–21, ∼33, and ∼100‐kyr, suggesting an optimal sedimentation rate of 3.1 m/Myr. Notably, we detected signals of millennial‐scale variability, aligning with the ∼1.5‐kyr Dansgaard‐Oeschger and ∼2.4‐kyr Hallstatt heliomagnetic cycles, even in deposits lacking visible laminae alternation. This finding bolsters the hypothesis of an external origin for these millennial‐scale features. Additionally, our reconstruction of sea‐level variations, using principal component analysis and sedimentary noise modeling, reveals two intervals of sea‐level fall and one sea‐level rise, linked to an astronomical forcing cycle of ∼1.2‐Myr. The obliquity band power‐total power ratios correspond to ∼1.2‐Myr periodicities for s4‐s3 term. The synchronization of ∼1.2‐Myr cycle minimum with a sea‐level drop (low PC1 value) suggests that glacio‐eustatic variations were influenced by ∼1.2‐Myr obliquity modulation cycles. This research enhances our understanding of glacio‐eustasy during the latest Ordovician from an astronomical perspective, offering valuable insights into the interplay between orbital cycles and Earth's paleoclimate. Key Points: Millennial‐scale cycles have been detected based on five high‐resolution proxy seriesMillennial‐scale cycle preserved in the Hirnantian was linked to the D‐O and Hallstatt cycle∼1.2‐Myr PC1 filter revealed one rise and two falls of sea‐level during Hirnantian [ABSTRACT FROM AUTHOR]

Chen, Y.; Huang, W., and Xu, S., 2014. Frequency analysis of extreme water levels in east and southeast coasts of China with analysis on effect of sea level rise. Qiantang bore as well as the storm surge are great disasters for river bank protection at the estuary of Qiantang River. Pearl River estuary is also frequently attacked by strong typhoon storm surge. The risk of damage from storm surge is expected to increase in both estuaries, exacerbated by sea level rise (SLR) and possible climate-induced increases in typhoon intensity and frequency. Adequate estimation on extreme water level will be essential to the coastal flood mitigation for both estuary areas with the effect of climate change. In this study, the popular frequency models Weibull, Lognormal, Gumbel, P-III and GEV are compared on Ganpu station located at the estuary of Qiantang River and Denglongshan station in Guangdong province, the optimal GEV model is recommended. For the risky analysis and management concern induced by the shortage of studied data, the estimated 50 year and 100 year extreme water levels respectively at Ganpu and Denglongshan stations are recommended in this study. Both studied stations located at different estuaries are all type II GEV model as the parameter of GEV distribution are higher than 0. The difference of the parameter and the reason causes the difference in the studied stations are analyzed and discussed in this paper. Furthermore, with the estimated 2.9mm/yr SLR by sea level bulletin of China, effect of SLR in frequency analysis on Denglongshan station is discussed. [ABSTRACT FROM AUTHOR]

Sea-level rise as a result of climate change increases inundation and erosion, which are affected by a complex interplay of physical environmental parameters at the coast. China's coast is vulnerable to accelerated sea-level rise and associated coastal flooding because of physical and socio-economical factors such as its low topography, highly developed economy, and highly dense population. To identify vulnerable sections of the coast, this paper presents a national assessment of the vulnerability of the Chinese coast using 8 physical variables: sea-level rise, coastal geomorphology, elevation, slope, shoreline erosion, land use, mean tide range, and mean wave height. A coastal vulnerability index was calculated by integrating the differentially weighted rank values of the 8 variables, based on which the coastline is segmented into 4 classes. The results show that 3% of the 18,000-km-long Chinese coast is very highly vulnerable, 29% is highly vulnerable, 58% is moderately vulnerable, and 10% is in the low-vulnerable class. Findings further reveal that large amounts of land and population will be vulnerable to inundation by coastal flooding from sea level rise and storm surge. Finally, some suggestions are presented for decision makers and other concerned stakeholders to develop appropriate coastal zone management and mitigation measures. [ABSTRACT FROM AUTHOR]

The Ximing Sandstone-to-No. 9 Coal succession of the Taiyuan Formation in the Linxing gas field records a complex internal architecture of a transgressive succession developed in the western coast of the late Pennsylvanian North China epeiric sea. Facies and sequence stratigraphic analyses reveal its depositional evolution from fluvial channels through fluvial-dominated and tide-influenced inner estuaries to tide-dominated estuaries and finally to wave-dominated barrier lagoons. The evolution from fluvial- to tide-dominated deposition has been ascribed to the funnel-shaped valley coupled with an increased tidal prism induced by the upstepping and backstepping shoreline. The evolution from tide- to wave-dominated deposition has been ascribed to the wide North China epeiric seaway lacking local coastline irregularities after the incised-valley fill that provided sufficient fetch for the occurrence of large storm waves. Grain-size analysis reveals the relative importance of traction, saltation, dispersed suspension, and flocculated suspension in the development of the transgressive estuarine to lagoonal deposits. This study not only contributes to a proper understanding of coastal depositional response to the relative sea-level rise but also provides a context within which to interpret the symbiotic relationship of the superimposed sandstone–shale–coal reservoirs and predict the distribution of favorable unconventional gas production formation. [ABSTRACT FROM AUTHOR]

A late Kasimovian (Pennsylvanian) coral reef is reported in the Yanbanzhai (YBZ) area, southern Guizhou Province, South China. The YBZ coral reef, with a thickness of approximately 5.5 m and a lateral exposure of nearly 50 m, is primarily composed of the colonial rugose coral Fomichevella. The fusulinids collected from the reef indicates a late Kasimovian age. Five microfacies types have been identified, including coated bioclastic grainstone, coral (Fomichevella) framestone, bioclastic wackestone, bioclastic grainstone, and peloidal grainstone. The vertical evolution of the microfacies in the YBZ coral reef indicates major sedimentary environmental changes associated with relative sea‐level changes. The growth of the reef‐builder Fomichevella was controlled by the transgression and regression. Deep water promoted the upward expansion of Fomichevella, while shallow water inhibited its growth. Published records of atmospheric pCO2 estimation and sea‐surface temperatures, combined with geochemical proxies, confirm a warm climatic period during the late Kasimovian. This is an interglacial period conducive to the growth of the coral reef. Sea‐level and climate changes associated with the Late Palaeozoic ice age (LPIA) are interpreted as significant controls of the development of the YBZ coral reef. This research of the YBZ coral reef in South China provides practical palaeobiological evidence for global sea‐level rising during the late Kasimovian period caused by the high‐latitude Gondwana delaciation. [ABSTRACT FROM AUTHOR]

Land subsidence is impacting large populations in coastal Asia via relative sea-level rise (RSLR). Here we assesses these risks and possible response strategies for China, including estimates of present rates of RSLR, flood exposure and risk to 2050. In 2015, each Chinese coastal resident experienced on average RSLR of 11 to 20 mm/yr. This is 3 to 5 times higher than climate-induced SLR, reflecting that people are concentrated in subsiding locations. In 2050, assuming these subsidence rates continue, land area, population and assets exposed to the 100-year coastal flood event is 20%-39%, 17%-37% and 18%-39% higher than assuming climate change alone, respectively. Realistic subsidence control measures can avoid up to two thirds of this additional growth in exposure, with adaptation required to address the residual. This analysis emphasizes subsidence as a RSLR hazard in China that requires a broad-scale policy response, utilizing subsidence control combined with coastal adaptation. Chinese coastal populations are concentrated in subsiding locations, and also subject to sea-level rise. Here the authors find that more areas, population and assets are exposed to coastal flooding by 2050 but realistic subsidence control measures can avoid additional risks. [ABSTRACT FROM AUTHOR]

Floods in river deltas are driven by complex interactions between astronomical tides, sea levels, storm surges, wind waves, rainfall‐runoff, and river discharge. Given the anticipated increase in compound flood hazards in river deltas in a warming climate, climate‐informed regional to local extreme water levels (EWLs) is thus critical for decision‐makers to evaluate flood hazards and take adaptation measures. We develop a simple yet computationally efficient stress test framework, which combines historical and projected climatological information and a state‐of‐the‐art hydrodynamic model, to assess future compound coastal‐fluvial flood hazards in river deltas. Our framework is applied in the world's largest single urban area, China's Pearl River Delta (PRD), which is also characterized by densely crossed river network. We find that extreme sea level is the dominant driver causing the compound coastal‐fluvial flood in the PRD over the past 60 years. Meanwhile, there is large spatial heterogeneity of the individual and compound effects of the typhoon intensity, local sea‐level rise, and riverine inflow on coastal‐fluvial floods. In a plausible disruptive scenario (e.g., a 0.50 m sea‐level rise combined with a 9% increase in typhoon intensity in a 2°C warming), the EWL will increase by 0.76 m on average. An additional 1.54 and 0.56 m increase in EWL will occur in the river network and near the river mouth, respectively, if coastal floods coincide with the upstream mean annual flood. Findings from our modeling framework provide important insights to guide adaptation planning in river deltas to withstand future compound floods under climate change. Plain Language Summary: Compound floods pose serious threats to the dense population living in river deltas worldwide. Climate change could increase the compound flood hazards through stronger tropical cyclones, sea level rise, higher extreme precipitation, and river flows. It is urgent to understand how the so‐called grey swan events will evolve under a changing climate in these already flood‐prone areas. Here, grey swan events are high‐consequence events that are beyond people's experience but may be foreseeable and thus can be systematically prepared for. In this study, a storyline‐based framework is proposed to assess the potential grey swan compound floods under a warming climate. We apply this framework to China's Pearl River Delta, the world's largest single urban area. In a plausible disruptive scenario (e.g., a 0.50 m sea‐level rise combined with a 9% increase in typhoon intensity in a 2°C warming), we find that extreme water levels will increase by 0.76 m on average. Our flexible and computationally efficient storyline‐based framework could guide coastal planners to prepare for the grey swan compound flood hazards under climate change. Key Points: A quantitative stress test framework is proposed to assess the compound coastal‐fluvial flood in the river delta at minimal costA state‐of‐the‐art unstructured mesh generation technology is applied to develop an objective and reproducible hydrodynamic modelCompound effects of typhoon intensity, local sea‐level rise, and river inflow on coastal‐fluvial floods are systematically investigated [ABSTRACT FROM AUTHOR]

Abstract: Holocene environmental change and environmental archaeology are important components of an international project studying the human-earth interaction system. This paper reviews the progress of Holocene environmental change and environmental archaeology research in the Yangtze River Valley over the last three decades, that includes the evolution of large freshwater lakes, Holocene transgression and sea-level changes, Holocene climate change and East Asian monsoon variation, relationship between the rise and fall of primitive civilizations and environmental changes, cultural interruptions and palaeoflood events, as well as relationship between the origin of agriculture and climate change. These research components are underpinned by the dating of lacustrine sediments, stalagmites and peat to establish a chronology of regional environmental and cultural evolution. Interdisciplinary and other environment proxy indicators need to be used in comparative studies of archaeological site formation and natural sedimentary environment in the upper, middle and lower reaches of the Yangtze River Valley. Modern technology such as remote sensing, molecular bioarchaeology, and virtual reality, should be integrated with currently used dating, geochemical, sedimentological, and palaeobotanical methods of analysis in environmental archaeology macro- and micro-studies, so as to provide a greater comprehensive insight into Holocene environmental and cultural interaction and change in the Yangtze River Valley area. [Copyright &y& Elsevier]

Against a background of climate change, Macau is very exposed to sea level rise (SLR) because of its low elevation, small size, and ongoing land reclamation. Therefore, we evaluate sea level changes in Macau, both historical and, especially, possible future scenarios, aiming to provide knowledge and a framework to help accommodate and protect against future SLR. Sea level in Macau is now rising at an accelerated rate: 1.35 mm yr over 1925-2010 and jumping to 4.2 mm yr over 1970-2010, which outpaces the rise in global mean sea level. In addition, vertical land movement in Macau contributes little to local sea level change. In the future, the rate of SLR in Macau will be about 20% higher than the global average, as a consequence of a greater local warming tendency and strengthened northward winds. Specifically, the sea level is projected to rise 8-12, 22-51 and 35-118 cm by 2020, 2060 and 2100, respectively, depending on the emissions scenario and climate sensitivity. Under the +8.5 W m Representative Concentration Pathway (RCP8.5) scenario the increase in sea level by 2100 will reach 65-118 cm-double that under RCP2.6. Moreover, the SLR will accelerate under RCP6.0 and RCP8.5, while remaining at a moderate and steady rate under RCP4.5 and RCP2.6. The key source of uncertainty stems from the emissions scenario and climate sensitivity, among which the discrepancies in SLR are small during the first half of the 21st century but begin to diverge thereafter. [ABSTRACT FROM AUTHOR]

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