EAGER: Deciphering boulder movement history using cosmogenic isotopes - a numerical investigation.

我们目前缺乏定量的现场指标来破译多久漂砾移动的河流或泥石流过程。 该项目旨在开发和运行数值实验，以测试巨石运动的频率是否可以从宇宙成因暴露测年中破译。初步建模表明，在某些情况下，可以根据巨石周围的暴露模式确定巨石移动事件的数量。拟议的工作将包括系统地调查可能的控制变量（例如，漂砾尺寸、侵蚀速率和遗传）对移动的侵蚀漂砾周围和内部核素浓度的平均值和空间方差的影响。这项工作的结果将成为未来实地采样活动的基础，这些活动旨在测量巨石运动，可能适用于各种环境（例如，河道、泥石流扇、冰碛）。巨石排列在许多河流的河床上，是景观演变速度的重要控制因素，但人们对它们的长期行为还没有很好的了解。大的，巨石移动事件的复发间隔往往超出了历史记录，使这些事件的概率约束不足。该项目旨在提高我们预测巨石移动事件频率的能力，以减轻灾害和恢复栖息地。它可能会导致量化罕见的，大规模的洪水和泥石流事件的能力，复发间隔大于1000年，这可能会导致重大的生命和财产损失。

We currently lack quantitative field metrics to decipher how often boulders move by fluvial or debris flow processes. This project aims to develop and run numerical experiments to test whether the frequency of boulder movement can be deciphered from cosmogenic exposure dating. Preliminary modeling has shown that, in some cases, the number of boulder movement events can be determined from the pattern of exposure around the circumference of a boulder. The proposed work would include systematic investigation of likely controlling variables (e.g., boulder size, erosion rate, and inheritance) on the mean and spatial variance in nuclide concentration around and within a mobile, eroding boulder. Results from this effort would form the backbone for future field sampling campaigns aimed at measuring boulder movement, potentially applicable to a wide range of environments (e.g., river channels, debris flow fans, moraines).Boulders line the beds of many rivers and are an important control on rates of landscape evolution, yet their long-term behavior is not well understood. The recurrence interval of large, boulder-mobilizing events is often beyond the historical record, leaving the probability of these events poorly constrained. The project aims to improve our ability to predict the frequency of boulder moving events for hazard mitigation and habitat restoration. It could potentially lead to the ability to quantify infrequent, large magnitude flood and debris flow events with recurrence intervals greater than ~ 1000 yrs, which can cause significant loss of life and property.