| 长江中游洪灾形成的地学分析 |
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| 引用本文： | 李长安, 陈国金, 皮建高. 长江中游洪灾形成的地学分析[J]. 第四纪研究, 2003, 23(6): 675-682. |
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| 作者姓名： | 李长安 陈国金 皮建高 |
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| 作者单位： | ①中国地质大学地球科学学院,武汉,430074;; ②湖北省水文地质工程地质大队,荆州,434100;; ③湖南省第二水文队,长沙,410014 |
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| 基金项目： | 国家自然科学基金 (批准号 :40 1 72 0 61 )资助项目,国家基础研究快速反应项目,中国地质调查局大调查项目 (项目号 :1 9991 2 3 0 0 0 3 0 1 4) |
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| 摘 要： | 地质地貌条件是长江中游洪灾形成的背景条件,近代洪水位不断上升是人-地不和谐作用下流域环境系统演化的结果.人类作用导致的多流归槽改变了长江中游河流的地貌过程和水文特性,致使洪水过程显著;大堤修筑导致堤外河漫滩出现泥沙加积,自1650年荆江大堤合拢以来,边滩总体淤积厚度为2.8～11.0m,平均淤积速率12.54～25.64mm/a;围湖造田导致江汉-洞庭平原蓄洪空间减少和"小水大灾"局面的形成;漫滩筑堤围垸严重影响了长江行洪,仅荆江段就有围筑的民垸84个,总面积为4895.95km2,民垸面积是泄洪面积的近9倍.因此,在认识自然规律的基础上,正确协调人-地-水关系,重建良性循环的流域环境系统,是解决长江中游的水患的根本出路.
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| 关 键 词： | 长江中游 洪水灾害 地学环境 人-地关系 |
| 收稿时间： | 2003-06-28 |
| 修稿时间： | 2003-06-28 |
GEO-SCIENTIFIC ANALYSIS OF THE FLOOD CALAMITY IN THE MIDDLE REACHES OF CHANGJIANG RIVER |
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| Li Chang'an, Chen Guojin, Pi Jiangao. GEO-SCIENTIFIC ANALYSIS OF THE FLOOD CALAMITY IN THE MIDDLE REACHES OF CHANGJIANG RIVER[J]. Quaternary Sciences, 2003, 23(6): 675-682. |
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| Authors: | Li Chang'an Chen Guojin Pi Jiangao |
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| Affiliation: | ① Faculty of Earth Sciences, China University of Geosciences,Wuhan 430074;; ② Hubei Hydrogeology and Engineering Geology Team,jingzhou 434100;; ③Hunan Second Hydrogeology Team,Changsha 410014 |
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| Abstract: | The regional landforms and the second Newcazhaysian tectonic sinking zone are the geologic background forming flood in the middle reaches of Changjiang River. The ground subsidence of Jianghan-Dongting plain with a speed of 5～10 mm/a, complicated geologic tectonics, geomorphology and lithology along the Jinjiang river play an important role in the formation of flood calamity. The rising of the flood level of Jingjiang and the increased flood calamity threatening are the result of disharmony between human activities and geologic function. (1)Some streams conflux led by human activities changes the landforms process and the hydrology in the middle reaches of Changjiang River. Because the changing amplitude of the water level and discharge of the single river is big and it doesn′t drain off large quantity of water from upper reaches, the flood progress is very remarkable. (2) The big dike building causes the Jingjiang flood level to rise continuously. Before the big dike was constructed, the mud and sand of Changjiang River was overflowing and silting up in Jianghan plain, the ground subsidence and the deposition of the mud and sand were placed in opposite equilibrium. After the big dike,Changjiang River is controlled between two dikes, the sediment space of mud and sand changed from the face form to the line form, causing the accumulation of mud and sand in the concave flood plain of the dike outside. Since Jingjiang dike was gathered together in 1650, the total thickness of the marginal bank is 2.8 to 11.0 m, the sedimentation velocity is 12.54 ～25.64 mm /a, the height of the channel bar is 5 ～10 m in general. The rising concave flood plain raised the flood level. At the same time, the ground inside the dike lowers continuously because of the tectonic subsidence (5 ～10 mm/a ) and lacking the compensation of the mud and sand. As a result, the height difference of the flood level between inside and outside dikes adds up continuously, the height difference is 8～16 m at present. (3) Reclaiming land around the lake reduces the floodwater storage space. For Jingjiang plain -four lake region for example, lakes spread densely in 1950 in four lake region, there are 123 lakes in total whose area was 2 429 km 2, but only 677 km 2 in 1980. Embanked land on the concave flood plain forms the situation of the flood storage room reducing and “water a little but flood calamity heavily". (4) Embanked land on the concave flood plain affects Changjiang River flood-flux badly. The civil embanked land area is 9 times as much as the flood-flux area, that is to say, the majority of the natural flood-flux area along the Jingjiang river is occupied by the civil embanked land. The research suggests that the gradually rigorous flood situation in Changjiang River is the result of basin environment system evolution led by human-nature inter-function. Accordingly, flood prevention cannot be only water-control. Firstly, we must study hard the natural evolution of basin environment system; Secondly, the function mechanism led by human activities for basin environment system should be analyzed; And finally, a harmonious basin environment system must be reconstructed by understanding nature and man-land relationship. Only so,the flood calamity of the middle reaches of Changjiang River can be lightened even solved essentially. |
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| Keywords: | the middle reaches of Changjiang River flood calamity geologic environment man-land relationship |
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