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

我们目前缺乏定量的现场测量方法来破译巨石通过河流或泥石流过程移动的频率。该项目旨在开发和运行数值实验，以测试巨石移动的频率是否可以从宇宙暴露年代中破译出来。初步模拟表明，在某些情况下，巨石移动事件的数量可以根据巨石周围的暴露模式来确定。拟议的工作将包括对可能的控制变量(例如，巨石大小、侵蚀速度和遗传)的系统调查，这些变量影响移动的、侵蚀的巨石周围和内部核素浓度的平均值和空间变化。这一努力的结果将成为未来旨在测量巨石运动的现场采样活动的支柱，可能适用于广泛的环境(如河道、泥石流扇、冰原)。巨石排列在许多河流的河床上，是控制景观演变速度的重要因素，但它们的长期行为尚不清楚。大型巨石移动事件的重复间隔往往超出了历史记录，使得这些事件的发生概率受到很大限制。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。它可能会导致对重复间隔大于约1000年的罕见、大规模洪水和泥石流事件进行量化，这可能会造成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.