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### 水库联合运行对库下汛期河道过水断面形态参数变化率的影响——以黄河内蒙古河段为例

1. 1. 中国科学院地理科学与资源研究所 中国科学院陆地水循环及地表过程重点实验室,北京 100101
2. 中国科学院大学,北京 100049
• 收稿日期:2014-10-28 修回日期:2015-01-29 出版日期:2015-03-20 发布日期:2015-03-20
• 作者简介:

作者简介：苏腾, 男, 山东泰安人, 硕士研究生, 主要研究方向为河流地貌学。E-mail: sut.12s@igsnrr.ac.cn

• 基金资助:
国家重点基础研究发展计划(973项目) (2011CB403305);国家自然科学基金项目(41271027)

### Impact of joint operation of reservoirs on the change ratio of downstream cross-sectional geometry parameters: A case study of the Inner Mongolian reach of the Yellow River

Teng SU1,2(), Suiji WANG1, Yanguo MEI1,2

1. 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
• Received:2014-10-28 Revised:2015-01-29 Published:2015-03-20 Online:2015-03-20
• Supported by:
National Basic Research Program of China (973 Program), No.2011CB403305;National Natural Science Foundation of China, No.41271027]

Abstract:

Studies of the impacts of reservoir operation on downstream channel changes have been a hot spot in fluvial geomorphology in the last decades. However, it remains unknown on how to quantitatively express channel adjustments induced by the joint operation of upstream reservoir systems. The joint operation of the Liujiaxia and Longyangxia reservoirs on the upper Yellow River since 1986 has significantly influenced downstream channel variations. The objective of the paper is to analyze the channel cross-section changes at Dengkou, Bayangaole, Sanhuhekou, and Toudaoguai gauge stations located in the Inner Mongolian reach of the upper Yellow River in the period 1978-1982 (the earlier period, before the joint operation) and the period 2008-2012 (the later period, after the joint operation). As for the four gauge stations, we calculated the change ratios of cross-sectional geometry parameters, including channel cross-section area, water width, mean water depth, and the ratio of width to depth, at a given water level after the flooding season. The results show that most of the change ratios of the geometry parameters increased remarkably after the flooding season. Furthermore, the change ratio of each parameter at all the channel cross-sections decreased significantly in the later period compared with that during the earlier period. The change ratio of the cross-section area decreased 3.4 times while that of the water width and mean water depth decreased 3.5 times and 2.8 times, respectively. Spatially, the downstream variations of the change ratio of the geometry parameters evolved from a convex curve in the earlier period to an "S"-shaped curve in the later period. The observed decreases of the change ratios of channel geometry parameters are due to the joint operation of large upstream reservoirs. These reservoirs stored a large amount of flood water and reduced the peak discharge and maximum flow velocity in the flooding season; as a result, the erosion ability of the floods decreased. With the joint operation of the large reservoirs, the Inner Mongolian reach of the Yellow River shrunk significantly in recent years and the channel is faced with a great risk of extreme floods. Therefore, it is necessary to reasonably utilize the dam's adjustment functions for a better control of runoff and sediment export in the flooding season. With effective measures taken, the channel can avoid further shrinkage and is thus ready for extreme floods.