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Predicting the effects of climate change on alpine rock slopes: Evaluation of paraglacial and periglacial drivers of rockfall in the European Alps

预测气候变化对高山岩石斜坡的影响：评估欧洲阿尔卑斯山落石的冰旁和冰缘驱动因素

基本信息

批准号：
316624774
负责人：
Dr. Daniel Dräbing
金额：
--
依托单位：
Departement Fysische Geografie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/316624774?language=en
关键词：
Predicting effects climate change alpine

项目摘要

Rockfall from alpine rockwalls represents a hazard to human life and infrastructure but also a natural process of rock slope evolution. Two contrasting hypotheses currently exist which aim to explain rock slope evolution: (1) a paraglacial adjustment of the rockwalls with increasing frequency due to deglaciation and a subsequent asymptotically decline of adaption and (2) a frost-weathering dominant adaption with steady-state rates. Climate change will affect alpine systems by an increase of temperatures and a decrease of frost weathering activity and glaciated area. Hypothesis (1) suggests an increase of rockfall frequency due to deglaciation. On contrary, hypothesis (2) expects a decrease of rockfall frequency due to the dislocation of highest frost cracking activity to higher altitudes. Both hypotheses are based on assumptions which have been never tested or validated in the field. As a consequence, the future adaption of rockwall to climate change is unknown.Very few studies focus on rockfall after deglaciation on different time scales. On the Holocene time scale, rockfall is relied to increase post glaciation. The findings are based on dating and derivation of erosion rates without incorporating mechanical or thermal rockwall properties. As a result, the observed increase cannot be traced back to paraglacial adjustment or frost weathering processes. On the contrary, rock slope erosion in recently deglaciating areas can integrate mechanical and thermal rockwall properties. However, the period to establish frequency-distributions is too short to draw conclusions on potential evolution due to climate change.This approach integrates Holocene and recent rock slope erosion in one investigation. The objectives of the study are (1) to quantify the thermal regime of the rockwalls, (2) to quantify the response of mechanical regime and establish a short-term erosion rate. Furthermore, the study will (3) increase the process understanding of frost weathering and (4) quantify long-term rock slope erosion. In a space-for-time substitution approach (5) a rock slope erosion model will be developed to bridge short-term and long-term rock slope failure. Fieldwork will take place in the Hungerli Valley, Valais Alps, and in the Gaisberg Valley, Ötztal Alps. State-of-the-art geomorphological, geotechnical and geophysical methods including refraction seismic tomography, electric resistivity tomography, terrestrial laserscanning, laboratory frost-weathering simulation and Be-10 dating will be combined to address the research objectives. Expected results include the temporal and spatial distribution of permafrost and frost weathering processes, the short-term adaption of rockwalls, an increase of understanding of frost weathering processes, a frost weathering model, a rock slope erosion model bridging short- and long-term rock slope erosion and the prediction of future rock slope evolution in the context of climate change and increased deglaciation.

高山岩墙落石是对人类生命和基础设施的危害，也是岩质边坡演化的自然过程。目前存在两种相反的假说，旨在解释岩石边坡的演变：（1）一个paraglacial调整的岩壁，由于冰消作用和随后的渐进下降的适应和（2）冻结风化占主导地位的适应与稳定状态的速度。气候变化将通过温度升高、霜冻风化活动和冰川面积减少来影响高山系统。假设（1）表明由于冰川消融，落石频率增加。相反，假设（2）预计由于最高冻裂活动向更高海拔的错位，落石频率会降低。这两个假设都是基于从未在实地测试或验证的假设。因此，岩壁未来对气候变化的适应性尚不清楚，对冰消期后不同时间尺度上的岩崩研究较少。在全新世时间尺度上，崩塌是冰后期增加的主要原因。这些发现是基于测年和推导侵蚀率，而不包括机械或热岩壁性能。因此，所观察到的增加不能追溯到冰缘调整或霜冻风化过程。相反，在新近冰川消退区的岩石边坡侵蚀可以集成的力学和热岩壁属性。然而，建立频率分布的时间太短，无法得出气候变化导致的潜在演变的结论。这种方法将全新世和现代岩石边坡侵蚀整合在一次调查中。本研究的目的是（1）量化岩壁的热状况，（2）量化机械状况的响应，并建立短期侵蚀速率。此外，该研究将（3）增加对霜冻风化过程的理解和（4）量化长期岩石边坡侵蚀。在时间空间替代方法（5）中，将开发岩石边坡侵蚀模型以桥接短期和长期岩石边坡破坏。实地考察将在瓦莱州阿尔卑斯山的Hungerli山谷和Ötztal阿尔卑斯山的Gaisberg山谷进行。将结合最先进的地貌学、岩土工程学和地球物理学方法，包括折射地震层析成像、电阻率层析成像、地面激光扫描、实验室霜冻风化模拟和Be-10测年，以实现研究目标。预期成果包括：永冻和冻风化过程的时间和空间分布、岩壁的短期适应、加深对冻风化过程的了解、冻风化模型、连接短期和长期岩坡侵蚀的岩坡侵蚀模型，以及在气候变化和冰消作用加剧的背景下预测未来岩坡的演变。