长江三峡建坝前后流量和海平面对感潮河段潮位的影响差异

Different effects of discharge and sea level on tide level before and after the construction of Three Gorges Dam

三峡大坝运行和海平面上升对河口水文动力变化的影响广受国内外关注。本文选取长江感潮河段沿程6个站(芜湖、马鞍山、南京、镇江、江阴和天生港) 1963-1985年(其中1970年和1971年数据缺失)和2003-2013年(其中2008年和2012年数据缺失)共30个年份的1月和7月的月均高潮位资料,以及相应月份上游大通站的流量(1950-2013年)、长江河口吴淞站潮位资料,通过肯德尔趋势分析、回归分析和偏相关分析等方法研究长江感潮河段潮位变化规律和影响因素。结果表明,三峡建坝后:(1)枯季流量和海平面的增加,导致上下段(以江阴为界)的潮位分别上升了0.33 m和0.20 m;洪季流量减少和海平面增加,导致上段潮位减小0.19 m、下段潮位增加0.04 m。(2)感潮河段洪季海平面与潮位回归方程的斜率均增加,表现为建坝后洪季洪涝灾害增加。(3)上下段流量和海平面对潮位贡献率的显著变化是导致上下段潮位呈现不同演变趋势的主要原因。

Responses of estuarine hydrodynamics to the implementation of Three Gorges Dam(TGD)and relative sea-level rise have attracted worldwide attentions.In this study,the monthly mean high tide level in January and July of 30 years from 1963 to 1985(Data for 1970 and 1971 are not available)and 2003 to 2013(Data for 2008 and 2012 are not available)at 6 hydrological gauging stations(i.e.the Wuhu,Ma`anshan,Nanjing,Zhenjiang,Jiangyin and Tianshenggang)along the Changjiang River Tidal Reach(YRTR)were selected,synchronous discharge at upstream Datong station(1950~2013)and tide level at Wusong station in the Changjiang Estuary were obtained.Based on the Mann-Kendall test,regression analysis and partial correlation analysis,herein,to study the tide level responses and relevant influencing factors in the YRTR during the post-TGD period.The results showed,after the TGD:(1)Both river discharge and sea-level increased during the dry season,which caused the mean tide level in the upper and lower sections(bounded by Jiangyin station)raised by 0.33 m and 0.20 m,respectively;however,the decreased river discharge and increased sea-level during the flood season generated the mean tide level declined and raised by 0.19 m and 0.04 m in the upper and lower sections.(2)The slope of the regression equation of sea-level and tide level increased during the flood season,thus,more frequent river flood events will be more likely triggered.(3)The contribution rate of discharge and sea-level to tide level varies significantly in the upper and lower sections,which is the main reason for the different evolution tendencies of tide level in the upper and lower sections.