讲座题目：Dunes in big rivers: some characteristics and considerations for collaborative research 主讲人：James Leonard Best 教授 主持人：程和琴 教授 开始时间：2019-06-06 10:00:00 讲座地址：闵行校区河口海岸大楼B101报告厅 主办单位：华东师范大学河口海岸学国家重点实验室
报告人简介： James Leonard Best，伊利诺斯大学香槟分校(UIUC)地质系、地理与地理信息科学、机械科学与工程系教授。其研究领域包括沉积物输运机制、现代沉积环境调查、古沉积沉解译。目前研究项目包括湍流与沉积物运动之间的相互作用、沉积物流中的湍流调制、底形动力学、辫状河流动力沉积、合流河道动力地貌、大河沉积学、多波束成像在沉积环境中的应用、盆地演化、古环境沉积学等。同时，他率先开发和应用了一系列新技术与方法，特别是实验技术（如相控激光多普勒测速法、超声多普勒速度剖面、基于两相微型PIV的微流场测试技术）和应用于大河沉积动力学的研究仪器（如ADCP、GPR和MBE等）。其成果在Nature、Nature Geoscience等顶级期刊上发表多篇学术论文。 James L. Best曾任沉积学旗舰刊物《Sedimentology》主编、《Developments in Sedimentology》丛书主编、《Sedimentology and Earth Surface Processes》期刊客座主编，《Nature》、《Science》、《Geology》、《Journal of Sedimentary Petrology/Research》等的编委，任国际沉积学协会主席团成员、美国国家科学基金会（NSF）地理和空间科学专家组成员、美国国家科学基金会（NSF）地球科学仪器和设施委员会专家组成员、英国工程和物理科学研究委员会（EPSRC）的理事会成员、英国自然环境研究理事会（NERC）同行评审学院创始成员。曾获英国地貌学研究机构“Gordon Warwick”杰出贡献奖。 报告内容： Dunes are perhaps the most common bedform in all river and estuarine channels, and are vital as regards flow resistance, bedload transport, ecological habitat and as a tool for reconstructing the dynamics of ancient alluvial sequences. Much of our knowledge concerning the dynamics of dunes has come from detailed laboratory and numerical simulations, which have provided exceptional detail concerning the fluid dynamics of dunes and the factors influencing their form and stability. Yet, these models have been largely unable, as yet, to reproduce the morphology and dynamics of dunes that are common in many of the world’s large rivers and estuaries, which tend to have a different morphology to those ‘classic’ dunes investigated in many laboratory studies. This realization has been led by use of new field technologies, such as multibeam echosounding (MBES) and acoustic Doppler current profiling (aDcp), which in the last decade have revolutionized our understanding of alluvial channel dynamics. This talk will detail several aspects of the morphology of dunes in big rivers and highlight areas for future research enabled by new technologies. The talk will: 1) Summarize on recent work examining the morphology, and especially leeside angle and shape, of dunes in a range of the world’s big rivers as revealed by MBES. These examples, including the Amazon, Mekong, Paraná, Mississippi, Missouri and Waal rivers, demonstrate that dunes are predominantly low-angle, with a segmented leeside profile, and thus will possess a very different fluid dynamics to ‘classic’ dunes. 2) Examine the morphology and superimposition of dunes within the Amazon River, Brazil, detailing their spatial distribution and importance for the styles of deposition represented within the rock record; 3) Detail the changing morphology of dunes within the fluvial-tidal transition of the Columbia River, USA, examining the controls upon this changing morphology and implications for sediment transport and deposition. The talk will provide examples using MBES imaging and pose a series of areas for fruitful future research efforts and collaborations, and in applications of major importance, such as assessing bedload transport rates, quantifying the effects of sand mining and assessing the ecological habitats of alluvial channel beds. |
