| 摘要: |
| 通过对长江三角洲地区埋藏古树、泥炭、以及海相贝壳测年资料以及地方志、历史文献当中关于研究区洪灾事件记录的搜集、整理,研究结果表明,由于长江三角洲地区地势低平这一地貌特点,使得海面变化对于研究区洪灾的发生有着重要的影响.在长江中下游地区,海面的上升是导致冰后期长江河谷泥沙加积的主要原因,随着海面的上升和河床的抬高,长江中下游的水位也随之上升,从而导致长江洪水期排泄不畅,加重了洪灾的影响,加上长江三角洲地势低平,使海面变化成为长江三角洲地区洪灾发生的一个重要影响因子.同时,海面上升对长江水流的顶托作用也是加剧洪灾危害的一个重要原因.本文对于未来研究区洪水发生的预测,加强海岸带地区自然灾害的预防工作,减少生命财产的损失,具有一定的理论与实践意义. |
| 关键词: 长江三角洲 古洪水研究 全新世 海面变化 |
| DOI：10.18307/2003.sup27 |
| 分类号: |
| 基金项目:中国科学院知识创新工程重要方向项目(长江中下游洪水孕灾环境变化、致灾机理与减灾对策,KZCX3-SW-331)和国家自然科学基金项目(历史时期长江中下游平原旱涝序列时空格局与风险评价No.40271112)联合资助 |
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| Sea Level Changes and Paleoflood Events since the Holocene Epoch in the Yangtze Delta Region |
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ZHANG Qiang, JIANG Tong
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Nanjing Institute of Geography and Limnology, CAS, Nanjing 210008, P. R. China
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| Abstract: |
| Wide collection is performed on the dating materials of buried paleo-trees, peat and shells, and also the cho-rography and historical document in the Yangtze Delta. All the 14C data are calibrated into calendar years. The sea level changes in the Yangtze Delta are reconstructed from the 14C-dated shell ridges and peat. The research results indicate that frequently occurring flood periods matched the climatically warm and wet periods well. 6 flooding periods correspond to the 6 periods characterized by relatively warm and humid. Humid and warm climate is in close relation to the occurrence of floods. Additionally, the Yangtze Delta is geomorphologically low-lying, making flood events occurred to the region susceptive to sea-level changes other than the main flood-inducing factors like excessive precipitation and human activities. In the middle and lower reaches of the Yangtze River, the rise of sea level plays a key role in the deposition of the sand on the riverbed. With the rise of the sea level and the rive bed, the water level of the middle and lower part of the Yangtze River rises correspondingly, the result of which is to make the discharge of excessive water difficult during the flood period, intensifying the loss induced from flood disasters. The pushing to the water flow of the Yangtze Hiver from the high sea level is also one of the factors intensifying the negative effect of the flood disaster. Digital modeling results indicate that rising of sea level is the main driving factor for the deposition of the riverbed sand after the Ice Age. The result of this deposition is the decreasing of the transportation capacity of the flood discharge, together with the rising of the sea level; all these factors make the transportation of the flood discharge more difficult. This paper put under consideration the influence the sea-level changes on the flood events occurred to the Yangtze Delta, the research results are theoretically and practically meaningful in forecasting the occurrence of flood disasters and strengthening the prevention of coastal disasters. |
| Key words: The Yangtze Delta paleoflood the Holocene sea-level changes |
