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Xu, Y.; Cheng, L.; Zheng, J.; Zhu, Y.; Wu, Y.; Shi, J., and Zhang, W., 2019. Intensive anthropogenic influence on the morphological evolution of estuarine tidal channels. Journal of Coastal Research, 35(6), 1237–1249. Coconut Creek (Florida), ISSN 0749-0208. Long-term and large-scale morphological consequences of human activities are important to consider during human settlement construction around estuarine environments. Thus the rapid human-induced changes in the geomorphology of estuarine areas commands a growing socio-economic and scientific interest. Lingding Bay, a part of the Pearl River estuary, is one of the areas that draws much attention in this respect. By using admiralty charts and topographic maps since the 1960s, decadal timescale morphological changes are investigated to understand the effects of human activities on estuarine tidal channels. The results show that the estuarine channels have undergone overall net erosion over this 50 year period, with a sequence of alternating erosion and deposition phases. On basis of the variations of aspect ratios and thalweg movements, five types of stable channels are identified. The upstream part of the east channel is the most unstable region defined as type 5, where the significant topographical change is principally associated with the unplanned sand mining activities. The whole west tidal channel is approaching relative stability because it was deepened as the main navigational channel, with the thalwegs being straighter. Based on empirical orthogonal function analysis, the anthropogenic effects, including the dredging, sand excavation, and land reclamation, are found to be of relatively major importance in the morphological evolution process of the estuarine channels. [ABSTRACT FROM AUTHOR]

Zhou, C.Y.; Zheng, J.H.; Dong, P.; Zhang, J.S.; Zhu, Y.L., and Zhang, Z.H., 2016. Tidal evolution in the Yellow and East China Sea during Holocene. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 785-789. Coconut Creek (Florida), ISSN 0749-0208. The impact of the sea level (SL) change on the propagation of tides in the Bohai Sea, Yellow Sea and East China Sea (BYECS) during Holocene was investigated by a 3D numerical model with SL of −60, −30, −15, 0 and +2 m, respectively. Same amplitude and phase of tidal constituents M2, S2, K1 and O1 were applied along the open boundaries in all the cases. The results showed that the number of amphidromic points of M2 increased from 2 to 4 while that of K1 increased from 1 to 2 as the SL rising. Both M2 and K1 co-phase lines rotated anti-clockwise as sea-level rising. S2 shared similar evolution pattern with M2 while O1 evolved similarly with K1. The +2 m SL can have significant influence on the tide pattern. Mainly because the new basin area enlarged, especially the vast area around the Subei and Changjiang estuary, also very near the amphidromes in the south Yellow Sea, which dissipated large amount of tide energy. The new coastline and bathymetry changed the propagation pattern of M2, the tide energy decreased significantly at the north Yellow Sea and Bohai Sea while increased along the Yangtze estuary and Korea west coast. The strong tidal current area corresponded well with the sand ridges during Holocene while weaker tidal current area corresponded with finer muddy deposit, indicating tide force is the dominate factor controlling the bedform generation and sediment distribution in BYECS. [ABSTRACT FROM AUTHOR]

Zheng, J; Zhang, W; Zhang, P, and Zhu, Y., 2014. Understanding space-time patterns of long-term tidal fluctuation over the Pearl River delta, South China. Principal component analyses (PCA) were used to identify the space-time patterns of long-term tidal fluctuation in the Pearl River delta (PRD) region. The tidal levels of the 35 stations over the entire PRD were divided into four regions by the PCA. The results show that different regions display different trends, indicating spatial variability of long-term tidal fluctuations in PRD region. The regional pattern of the first component loadings is mainly located near the outlets. Time series of the factor scores of the the first principal component (PC) shows a significant increasing trend. The regional pattern of the second component loadings is concentrated in the upper part of the PRD region. The factor scores of the the second PC, however, display a significant deceasing trend. The trend in the factor scores of the the third PC of the middle part of the North River is not significant, but it has to face the highest flood risk. As for the upper part of the East River, the factor scores of the the fourth PC also show a significant downward trend that demonstrates that the tidal level shows an obviously decreasing trend in the upper part of the East River. The impacts of the intensive human activities on these changes in the PRD region in the latest three decades are the dominant factor. In particular, the large-scale and long-term sand excavation in the whole PRD region directly results in the riverbed down-cutting, leading to the tidal level in the upper part of the delta decreasing obviously. More tidal prism can enter the delta much more easily also due to the sand excavation, which can fill out the volume not only to keep the tide level, but also even increase the tide level in the middle part of the North River. What's more, intensive reclamation in the estuary is another main factor for tide increase at the outlets of the PRD region. [ABSTRACT FROM AUTHOR]