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

岩石的风化破碎是高山沉积瀑布的第一步。风化过程受昼夜加热和降温、湿润和干燥、昼夜和季节性冻结和融化或季节性活跃层融化的影响。这些过程单独或结合在一起，导致裂缝的亚临界或临界扩展，从而准备和触发落石。落石过程是高山景观演变的关键因素，但也给游客和基础设施带来了危险。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间和空间信息。为了根据可预见的气候变化预测风化过程和相关崩塌的轨迹和速率，有必要加强对过程的了解。我们遵循一个集成了温度和降水/水分梯度的概念多尺度模型，该模型取决于海拔和坡向：(1)在实验室尺度上，我们将模拟受控条件下的温度循环、湿润和干燥以及霜冻风化，以量化裂缝活动，并建立温度/水分-裂缝活动关系，结合声发射传感器、裂纹仪、湿度和温度探头以及电阻率测量。(2)在Rockwall标尺上，缺乏信息的部分原因是野外测量岩石湿度的难度。我们将使用温度和自行开发的湿度传感器、裂纹计和气象站来监测温度、水分和岩石运动学。我们将使用2D电阻率测量和红外摄影来不连续地量化岩石水分和温度的空间差异。达姆卡尔和达赫斯坦研究区的石灰岩岩壁被选为覆盖海拔1400至3000米和南北两面。(3)我们将使用我们在实验室和Rockwall尺度上的结果来模拟山区尺度的岩石风化，应用已经测试过的基于地理信息系统的地质统计学和岩石力学模型和模拟工具，以克服目前使用的纯粹由温度驱动的模型的局限性。我们将把结果与我们将从重复的地面激光扫描测量中创建的落石数据进行比较。此外，我们将调整我们的温度条件，通过结合气候情景来模拟小冰期以及2050年和2100年的气候条件。该项目的创新之处在于在空间尺度上研究岩石风化，解决过程相互作用，并首次将岩石水分和岩石力学参数结合在一起。这将对岩石风化和相关的崩塌产生新的见解，这是了解过去和未来阿尔卑斯山地貌演变以及预测未来风化和崩塌轨迹以减轻阿尔卑斯山灾害所必需的。

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.