Characterizing Rockwall Weathering from Microclimate, Rock Moisture and Rockfall Acitvity – ClimRock

风化作用导致的岩石破碎是高山沉积物级联的第一步。风化过程受昼夜加热和冷却、干湿、昼夜和季节性冻融或季节性活动层融化的影响。这些过程单独或共同导致裂缝的亚临界或临界扩展，从而准备和触发岩崩。岩崩过程是高寒景观演变的关键因素，但也对游客和基础设施造成危害。尽管如此，人们对热和水分驱动的风化过程知之甚少，特别是缺乏关于岩壁水分的时空信息。根据可预见的气候变化，提高对过程的理解对于预测风化过程和相关岩崩的轨迹和速率是必要的。我们遵循一个概念性的多尺度模型，将温度和降水/湿度梯度整合在一起，这取决于海拔和方向：(1)在实验室尺度上，我们将模拟受控条件下的温度循环、干湿和霜风化，结合声发射传感器、裂缝计、湿度和温度探头以及电阻率测量，量化裂缝活动并建立温度/湿度-裂缝活动关系。(2)在岩壁尺度上，由于野外岩石水分测量困难，导致信息缺乏。我们将使用温度和自行开发的湿度传感器、裂纹计和气象站监测温度、湿度和岩石运动学。我们将利用二维电阻率测量和红外摄影技术，不连续地量化岩石湿度和温度的空间差异。选取Dammkar和Dachstein研究区的石灰岩岩壁，覆盖海拔1400 ~ 3000 m，南北两面。(3)我们将利用我们在实验室和岩壁尺度上的结果来模拟山尺度上的岩石风化，应用已经测试过的基于gis的地质统计和岩石力学模型和模拟工具，以克服目前使用的纯温度驱动模型的局限性。我们将把结果与我们将从重复的地面激光扫描调查中产生的岩崩数据进行比较。此外，我们将调整温度条件，通过纳入气候情景来模拟小冰期和2050年和2100年的风化条件。该项目的新颖之处在于跨空间尺度研究岩石风化，解决过程相互作用，并首次整合岩石水分和岩石力学参数。这将为岩石风化和相关的岩崩提供新的见解，这需要了解过去和未来的阿尔卑斯山景观演变，并预测未来的风化和岩崩轨迹，以减轻阿尔卑斯山的危害。

Rock breakdown by weathering is the first step of the alpine sediment cascade. Weathering processes are influenced by diurnal heating and cooling, wetting and drying, diurnal and seasonal freezing and thawing or seasonal active-layer thawing. Individually or in combination, these processes result in the subcritical or critical propagation of fractures that act to prepare and trigger rockfalls. Rockfall processes are a key agent of alpine landscape evolution but also present hazards to tourists and infrastructure. Nonetheless, thermal- and moisture-driven weathering processes are poorly understood and particularly, temporal and spatial information on moisture in rockwalls are lacking. Improved process understanding is necessary to anticipate trajectories and rates of weathering processes and associated rockfall in light of foreseeable climate change. We follow a conceptual multiscale-model integrating temperature and precipitation/moisture gradients, which depend on elevation and aspect: (1) On laboratory scale, we will simulate temperature cycles, wetting and drying and frost weathering under controlled conditions to quantify cracking activity and develop temperature/moisture-cracking activity relationships, combining AE sensors, crackmeters, moisture and temperature probes and resistivity measurements. (2) On rockwall scale, the lack of information results partially from the difficulty to measure rock moisture in the field. We will monitor temperature, moisture and rock kinematics using temperature and self-developed moisture sensors, crackmeters and meteo stations. We will quantify spatial differences of rock moisture and temperature discontinuously using 2D resistivity surveys and IR photography. The limestone rockwalls in the Dammkar and Dachstein research areas were selected to cover an altitudinal range from 1400 to 3000 m and north and south faces. (3) We will use our results on laboratory and rockwall scale to model rock weathering on mountain scale, applying already tested GIS-based geostatistical and rock mechanical models and simulation tools, to overcome the limitations of currently used purely temperature-driven models. We will compare the results with rockfall data that we will create from repeated Terrestrial Laserscanning surveys. Furthermore, we will adjust our temperature conditions to simulate weathering condition during the Little Ice Age and in 2050 and 2100 by incorporating climate scenarios. The novelty of this project is the investigation of rock weathering across spatial scales, addressing process interactions and integrating rock moisture and rock-mechanical parameters for the first time. This will create new insights on rock weathering and associated rockfall, which are required to understand past and future Alpine landscape evolution and to anticipate future weathering and rockfall trajectories to mitigate Alpine hazards.