Intensive Anthropogenic Influence on the Morphological Evolution of Estuarine Tidal Channels

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.