| 三门峡水库影响渭河下游河道横向演变的研究 |
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| 引用本文： | 庞炳东.三门峡水库影响渭河下游河道横向演变的研究[J].地理研究,1997,16(3):39-46. |
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| 作者姓名： | 庞炳东 |
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| 作者单位： | 北京气象学院 北京 100081 |
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| 摘 要： | 多沙河流修建水库影响库区河道演变,建库前后河道遵循不同的演变规律,兴建三门峡水库后的15年间赤水河河口至陈村河段发生了7次自然裁弯,三门峡水库改建后20年间却没有发生一次自然裁弯,这是一个非常有趣的现象。文中利用渭河下游河道的实测资料,对比兴建三门峡水库前后以及三门峡改建前后渭河下游河道的横向演变,得到如下几点认识:(1)侵蚀基准面的变化是引起渭河下游河道横向摆动的主要因素;(2)洪水比降变平,相应河道弯曲系数变大,河道由稳定型向摆动型发展;洪水比降变陡,相应河道弯曲系数变小,河道由摆动型向稳定型发展;(3)滩地的泥沙组成代表河岸的可动性。河岸可动性增大,河道由稳定型向摆动型发展,河岸可动性变小,河道由摆动型向稳定型发展;(4)河道断面形态的调整是对基准面变化和来水来沙变化的复杂响应过程;(5)来水来沙影响渭河下游河道横向演变。
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| 关 键 词： | 多沙河流 横向演变 侵蚀基准面 弯曲系数 |
| 收稿时间： | 1997-02-03 |
| 修稿时间： | 1997-06-03 |
EFFECTS OF SANMEMXIA RESERVOIR ON LATERAL FLUVIAL PROCESSES IN THE LOWER WEI RIVER |
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| Pang Bingdong.EFFECTS OF SANMEMXIA RESERVOIR ON LATERAL FLUVIAL PROCESSES IN THE LOWER WEI RIVER[J].Geographical Research,1997,16(3):39-46. |
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| Authors: | Pang Bingdong |
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| Institution: | Beijing Institute of Meteorology, Beijing 100081 |
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| Abstract: | The reservoir of the river with high concentration has influences on fluvial process.There were seven natural cut-offs occurred in the lower Wei River from 196l to 1975.After the reconstruction of the Sanmenxia Project the natural cut-offs in the lower Wei River did not occur from 1976 to 1996.By the analyses of the field observed data it is found that the above-mentioned phenomenon is caused by the following factors, (1) The bed elevation of Tongguan serves as a local base level to the lower Wei river.The natural cut-offs occurred after a rise of the bed elevation of Tongguan.2) After the construction of the Sanmenxia Reservoir, the river slope of the lower Wei River became gentle.meanwhile the bend coefficient was getting large.After the reconstruction of the Sanmenxia Project, the river slope became steeper, the bend coefficient became small.3) After the construction of the Sanmenxia Reservoir, the bed material of the new.flood-plain became loose, incoherent and easy to be eroded.The natural cut-offs occurred with small ratio of cut-off.The mean ratio of cut-offs was 3.42.(4) After the construction of the Sanmenxia Reservoir, the discharge capacity at the bankfull stage was reduced.The probability of flow over its flood-plain became high.lt provided more chance for the flood inundate its flood-plain.(5) When the kinetic 1ine of over-bank flood with hyperconcentration coincides with the ditch, the ditch may more probably develop into a new main channel and the natural cut-offs Complete finally.After the reconstruction of the Sanmenxia Project, the main channel of the lower Wei River was eroded in depth and widened in width.The discharge capacity at the bankfull stage was recovered and increased.Meanwhile, due to the bed of the river was degraded deeply into old river.bed level, the materials of the river bank consist of two parts.The lower part consists of coherent fine particle sediment;the upper part consists of incoherent coarse particle sediment, so the collapses of the river concave bank slow down.Since the rainfall was rare, from 1976 to 1990, just one flood was over the flood-plain in 1981, and the duration of the flood was short.Therefore, after the reconstruction.of the Sanmenxia Project, the lower Wei River lost the abovementioned essential condition for natural cut-offs. |
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| Keywords: | river with high concentration lateral fluvial processes local base level bend coef- ficient |
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