海平面上升的淹没效应和岸滩冲淤对潮间带湿地面积影响的分离估算

海平面上升的淹没效应导致潮间带湿地面积损失,泥沙淤积可以抵消海平面上升的影响而使潮间带湿地面积持续增长。潮间带湿地面积的实际变化取决于这两个因素的抗衡。本文通过对崇明东滩固定断面高程的重复测量,结合海平面上升速率和潮间带坡度,尝试分离海平面上升和泥沙淤积两因子对潮间带湿地面积变化的影响。结果表明,2005～2010年间,泥沙淤积使崇明东滩潮间带湿地面积增加1.79km2（平均0.36km2/a）,而相对海平面上升的＂淹没＂效应导致崇明东滩潮间带湿地面积损失约0.44～0.64km2（0.09～0.13km2/a）,潮间带面积实际增长1.15～1.35km2（0.23～0.27km2/a）。今后几十年,受全球海平面加速上升和长江入海泥沙进一步减少的影响,崇明东滩潮间带湿地的净淤涨速率可能进一步下降,崇明东滩湿地的开发利用将面临新的挑战。

Separation Estimate of Beach Erosion and Deposition on Intertidal Wetland Because of Sea Level Rise and Normal Deposition

Swamping effect of sea level rise causes intertidal wetlands loss,while sedimentation could make the intertidal area continued growth.The actual changes of the intertidal wetland depend on these two factors.Based on the repeated measurements of three fi xed cross-section elevation and combined sea level rise rate and the slope of the intertidal zone,this paper is trying to distinguish the impact of these two factors to the development of the intertidal zone.The results show that,sedimentation caused Eastern Chongming intertidal wetland area increased by 1.79km2（average 0.36 km2/a） from 2005 to 2010,while swamping effect of relative sea level rise led to Eastern Chongming intertidal wetland area loss of about 0.44~0.64 km2（0.09~0.13km2/a）,and the actual increase of the intertidal wetland area was 1.15~1.35km2（0.23~0.27km2/a）.In the coming decades,the global sea level rise will accelerate and the sediment from Yangtze River to the sea will further reduce,so the net deposition rate of Eastern Chongming intertidal zone may decline further,and the development and utili-zation of Chongming wetlands will face new challenges.