Collaborative Research: Defining controls on incisional avulsions in alluvial basins

合作研究：确定冲积盆地切割撕裂的控制河流撕裂发生在河流分流并在周围的泛滥平原上创造了一条新的渠道时。相关的洪水对生活在河流沿岸的人们来说可能是灾难性的，但减灾是困难的，因为模型无法预测河流撕裂的时间、位置或类型。当一条新的河道是通过侵蚀而不是沉积建立起来的时候，就会发生切割性撕裂，尽管这种撕裂在一些河流系统中很常见，但这种撕裂方式尤其鲜为人知。这项研究的目的是确定与切开撕脱相关的沉积学和水动力学条件。利用联合建模和现场方法，PI将评估诸如洪泛平原地形、坡度、地面覆盖和岸上沉积等特征如何控制撕裂类型，并检验切割撕裂发生在地形崎岖、无植被、排水良好的泛滥平原中发生的假设，这些洪泛平原缺乏充足的岸上悬浮泥沙供应。模拟工作将使用Delft3D，这是一个基于物理的数值模型，求解水流和泥沙运动方程，现场数据收集将集中在古地层，在那里可以测量大量古撕裂沉积的河道和滩地特征。该项目的结果将有助于提高撕裂洪水危险性的预测，并将加深对河道撕裂与滩地冲刷和沉积之间关系的理解。撕裂作用也是河流相油气、地下水和二氧化碳储集层分布的主要控制因素。通过这项研究获得的对撕裂过程的更好理解将有助于地下对储集层质量和位置的预测。这项工作的更广泛影响还包括开发一个关于河流和撕裂的自定进度的基于网络的教育模块。与地球科学推广基金会合作，专业人员将设计上述河流课程，其中包括使用谷歌地球和谷歌地图进行河流和撕裂的导游。来自上方的河流将重点关注河流形态和形态，河流撕裂，以及对社会的撕裂影响。PIS将与宾夕法尼亚州立大学和波士顿学院的外联办公室合作，在匹兹堡和波士顿地区的学校开发、试点测试和评估模块活动，目标是每个地区服务不足的社区。最后，这项建议还将支持对几名研究生和本科生的教育和培训，以及两名初级教员的早期职业生涯。

Collaborative Research: Defining controls on incisional avulsions in alluvial basinsRiver avulsion occurs when water is diverted out of a river and creates a new channel on the surrounding floodplain. The associated flooding can be catastrophic for people living along rivers, but hazard mitigation is difficult because models cannot predict the timing, location, or style of river avulsion. Incisional avulsion occurs when a new river channel is established through erosion rather than deposition, and, although it is common in some river systems, this avulsion style is particularly poorly understood. The goal of this study is to define the sedimentologic and hydrodynamic conditions associated with incisional avulsions. Using combined modeling and field approaches the PIs will evaluate how characteristics such as floodplain topography, slope, ground cover, and overbank deposition control avulsion styles and test the hypothesis that incisional avulsions occur in steep fluvial systems with topographically rough, unvegetated, well-drained floodplains that lack abundant overbank suspended-sediment supply. Modeling work will be conducted with Delft3D, a physics-based numerical model that solves the equations for water flow and sediment transport, and field-data collection will focus on ancient strata where channel and floodplain characteristics can be measured for large numbers of paleoavulsion deposits.The results from this project will help improve prediction of avulsion flood hazards and will enhance understanding of the relationships between channel avulsion and floodplain erosion and deposition. Avulsion is also a primary control on the distribution of fluvial hydrocarbon, groundwater, and CO2-storage reservoirs. Better understanding of avulsion processes gained through this research will aid subsurface predictions of reservoir quality and location. Broader impacts of this work also include development of a self-paced, web-based education module about rivers and avulsions. In collaboration with the Geoscience Outreach Foundation the PIs will design a Rivers from Above curriculum comprising guided tours of rivers and avulsions using Google Earth and Google Maps. Rivers from Above will focus on river forms and patterns, river avulsion, and avulsion impacts on society. The PIs will work with the outreach offices at Penn State and Boston College to develop, pilot test, and evaluate module activities in Pittsburgh- and Boston-area schools, targeting underserved communities in each region. Finally, this proposal will also support the education and training of several graduate and undergraduate students and the early careers of two junior faculty members.