上海石化近岸海床冲淤特征与海堤稳定性分析

ANALYSIS ON THE EROSION-ACCRETION CHANGES OF SHANGHAI PETROCHEMICAL COMPLEX OFFSHORE SEABED AND THE SEAWALL STABILITY

运用GIS对2000-2013年上海石化近岸海床冲淤特征、机制及海堤稳定性进行研究。结果表明：（1）2000-2013年海床大范围为淤积区,但金山深槽冲刷强度较大。其中,2000-2004、2004-2008年以冲刷为主,年均净冲刷速率为5.27cm和10.52cm;2008-2012年以淤积为主,年均净淤积速率为8.50cm;2012-2013年冲淤较稳定,稳定区占总面积的76.04%;（2）8个断面北岸及深槽中部（断面Ⅴ）地形较稳定,但在深槽西部（断面Ⅰ和Ⅱ）和东部（断面Ⅶ和Ⅷ）南侧冲刷;离岸15m以浅海床以淤积为主;（3）海堤稳定评估中,第六次围堤岸段稳定性较低。总之,海床的冲刷与金山涨潮冲刷槽补沙机制的丧失有关,同时城市沙滩、南汇促淤等工程也有影响,新一轮涉水旅游项目正在开发中,需密切关注。

The erosion-accretion characteristics and the underlying mechanisms of the Shanghai Petrochemical Complex（SPC） offshore seabed in 2000--2013, together with the stability evaluation of the seawall was studied with GIS software. Results indicate that： （1） Most areas of the seabed were in state of accretion in 2000--2013, but there emerged a great scouring intensity in the Jinshan Trough. Among them, the evolution of study areas was given priority to erosion in 2000--2004 and 2004--2008, with an average annual net erosion rate of 5.27 cm and 10.52 cm, respectively. But it was in accretion state in general in 2008--2012, with an average annual net accretion rate of to 8.50 cm. The study areas were mostly in steady state in 2012--2013, accounting for 76.04% of the total. （2） Analyses on the 8 cross sections showed that the terrain in the north was in relatively steady state. The terrain in the middle of the deep trough （section V） was stable, but the Jinshan Trough was scoured southward in the west （section Ⅰ and Ⅱ） and east （the section Ⅶ and Ⅷ）. And the areas shallower than 15 m were given priority to accretion in the south of study areas. （3）The seawall stability evaluation showed that the seawall was in primary and secondary stability level centrally distributed on the sixth coastal levee. For more than a decade, the erosionaccretion characteristics of the SPC offshore seabed was closely related to the loss of sand transport in Jinshan flood trough, and wading engineering constructions such as city beach and large-scale deposition promotion projects in Nanhui. New wading tourism development project is under developing, which still need much more concern.