珠江口伶仃洋地貌特征演变与纳潮能力变化研究

Morphological change and tidal prism variation in the Lingdingyang, Zhujiang River Estuary

在自然和人为的双重作用下,珠江口伶仃洋地貌特征发生了巨大变化,改变了水动力环境,致使纳潮能力也发生深刻变化。本文以珠江口伶仃洋地貌变化和纳潮能力变化为研究对象,采用近百年来的古地图资料、人类活动和水文特征等资料,通过第四纪地质学、地图学、遥感学、历史地理学等方法,反演内伶仃洋形态变化过程,探讨1906年以来珠江口伶仃洋的地貌变化过程。采用岸线分维数、形状指数、纳潮量、潮差消减能力,定量反映地貌变化对纳潮能力的影响。结果表明,1906-2014年,地形演变造成伶仃洋纳潮量减少了14.50%;1971-2014年,伶仃洋纳潮量减少了11.27%。海岸线的变化引起纳潮能力逐渐变弱,潮差沿程变化率减小了0.23,尤其是自1971年以来,因堤围等建设,河口岸线逐渐平直,纳潮能力逐渐减弱。

The geomorphic features in the Zhujiang River Estuary have changed tremendously due to natural processes and human activities over the last century, and these changes have led to the variations in the hydrodynamic environment such as the reduced tidal prism in the estuary. In this paper, the relation between geomorphic features and the tidal prism was analyzed. In order to identify how the historical landform change affects the tidal prism, we investigated the morphology change in the Lingdingyang Estuary through the analyses of historical topographic maps and nautical charts. The shape index and fractal dimension were introduced as indicators to reflect coastline changes that affect the tides. The tidal dissipation rate and tidal influx were found to represent the tidal prism. The results show that the tidal influx in the Lingdingyang has declined by 14.50% since 1906 under the morphological change. The tidal dissipation rate weakens subject to the morphological changes and the tidal dissipation rate decreases by 0.23. Meanwhile, the tidal reduction capability is weakened due to the coastline change, which has become the straight artificial coastline under the embankment construction especially since 1971.