| 基于HEC-RAS及GIS的川西叠溪古滑坡堰塞湖溃决洪水重建 |
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| 引用本文： | 马俊学,陈剑,崔之久,刘蓓蓓. 基于HEC-RAS及GIS的川西叠溪古滑坡堰塞湖溃决洪水重建[J]. 现代地质, 2022, 36(2): 610-623. DOI: 10.19657/j.geoscience.1000-8527.2021.168 |
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| 作者姓名： | 马俊学 陈剑 崔之久 刘蓓蓓 |
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| 作者单位： | 1. 中国地质大学(北京) 工程技术学院,北京 100083;.北京大学 城市与环境学院,北京 1008712. 应急管理部 国家减灾中心,北京 100124 |
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| 基金项目： | 国家重点研发计划项目(2018YFC1508806,2018YFC1505003)；;国家自然科学基金重点项目(41230743);国家自然科学基金面上项目(41571012)； |
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| 摘 要： | 青藏高原东南缘岷江上游地区地质环境条件十分复杂,滑坡堵江灾害及堰塞湖溃决事件频发,重建其灾害演化过程对于地区性防灾减灾和风险控制具有重要指导意义。以川西岷江上游叠溪古滑坡堰塞湖为研究对象,首先利用高精度DEM和ArcGIS软件重建了叠溪古堰塞湖的原始规模,其原始最大湖水面积为1.1×107 m2,相应的湖容量为2.9×109 m3;然后采用经验公式法和HEC-RAS一维水力学模型重建叠溪古堰塞湖溃决洪水的水力学特征。计算结果表明,HEC-RAS模拟的最大溃决洪水洪峰流量为73 060 m3/s,与经验公式法计算结果(74 500~76 800 m3/s,平均值76 000 m3/s)非常接近,误差小于5%。对应的最大洪水深度和流速分别为70.1 m和16.78 m/s,模拟河段的洪水淹没范围约为6.08 km2。综合误差分析推测的溃决洪峰流量误差范围为69 000~81 000 m3/s。叠溪古滑坡堰塞湖溃决洪水在世界范围内是十分罕见的,其最直接的影响是在下游数公里范围的河谷内形成大量带状或台阶状的溃坝堆积体和巨砾石堆积“阶地”,且这种影响仍延续至今,这与前人关于高能洪水水文特征和沉积特征的研究认识高度一致,证明本研究成果是非常可靠的。此外,本研究还表明,HEC-RAS一维水力模型可用于高山峡谷地区古滑坡堰塞湖溃决洪水重建研究,可为青藏高原东南缘岷江上游古环境重建和地貌演化提供参考。
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| 关 键 词： | 古滑坡堰塞湖 溃决洪水 洪峰流量 HEC-RAS 误差分析 岷江上游 |
| 收稿时间： | 2021-05-20 |
| 修稿时间： | 2022-03-01 |
HEC-RAS-/GIS-Based Paleohydraulic Reconstruction of the Diexi Ancient Landslide-Dammed Lake Outburst Flood in Western Sichuan Province |
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| MA Junxue,CHEN Jian,CUI Zhijiu,LIU Beibei. HEC-RAS-/GIS-Based Paleohydraulic Reconstruction of the Diexi Ancient Landslide-Dammed Lake Outburst Flood in Western Sichuan Province[J]. Geoscience of Geosciences, 2022, 36(2): 610-623. DOI: 10.19657/j.geoscience.1000-8527.2021.168 |
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| Authors: | MA Junxue CHEN Jian CUI Zhijiu LIU Beibei |
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| Affiliation: | 1. School of Engineering and Technology, China University of Geosciences, Beijing 100083, China2. College of Urban and Environmental Sciences, Peking University, Beijing 100871, China3. National Disaster Reduction Center of China, Ministry of Emergency Management of China, Beijing 100124, China |
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| Abstract: | Landslide-dammed lakes and outburst floods have been widely developed along the Upper Minjiang River valley, due to the complex geological environmental conditions in this region. Hazard evolution reconstruction has major significance for regional disaster prevention and mitigation. This study is dedicated to the Diexi ancient landslide-dammed lake (DALL) triggered by a strong paleoseismic in the Upper Minjiang River in Western Sichuan Province, at the southeastern margin of the Tibetan Plateau. We focus on the fluid dynamics of downstream megaflood characteristics. The estimated former lake size was 1.1×107 m2, and the impounded volume was 2.9×109 m3. The maximum peak discharge and paleohydraulics of the landslide-dammed lake outburst flood (LLOF) were reconstructed with empirical equations and one-dimensional (1D) HEC-RAS hydraulic numerical model. The results reveal that the maximum peak flow of the Diexi ancient LLOF by HEC-RAS was 73,060 m3/s, largely similar to the results by the empirical methods (74,500-76,800 m3/s, avg. 76,000 m3/s), with an error of < 5%. The corresponding maximum flood depth and flow velocity are 70.1 m and 16.78 m/s, respectively. The inundated area during the modeled reach of Minjiang River was approximately 6.08 km2. The uncertainty bound of the maximum peak discharge was determined to be 69,000-81,000 m3/s. The maximum peak discharge of the Diexi ancient LLOF was more than one hundred times the average annual flow of Minjiang River (approximately 700 m3/s), indicating that it was an abnormally large outburst flood in Diexi Region once in a hundreds-of-thousand years in history, and also one of the world’s largest LLOFs. The direct consequence of the high-energy outburst flood was the formation of band- or terrace-shaped outburst deposit bars and boulder deposit terraces on both sides of the gorge and river-bed in the downstream. These findings are consistent with previous hydrological and sedimentary studies on the high-energy outburst floods, demonstrating the high reliability of our results. In addition, this study also shows that the 1D HEC-RAS model can be used to reconstruct the hydraulics of an ancient LLOF in deep-confined gorge environments. This study is of great significance to the paleoenvironment reconstruction and geomorphic evolution in the upper reaches of Minjiang River. |
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| Keywords: | ancient landslide-dammed lake outburst flood peak discharge HEC-RAS uncertainty assessment Upper Minjiang River |
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