Gradenbach-Eggerberg rockslope deformation: Mountain water level and slope movement measurements

Gradenbach-Eggerberg rockslope deformation: Mountain water level and slope movement measurements Documentation of the mountain water level and mass movement data records on the Eggerberg slope (Gradenbach, Carinthia, Austria) used for analyses in publication A. Hormes (2025) Austrian Research Centre for Forests (BFW) Institute for Natural Hazards, Unit Torrent Process & Hydrology K. Hagen, A. Hormes, U. Stary, E. Lang, G. Priesch, A. Köhler, First published October 2025 Contact: [email protected] Content Content 1 1. Introduction 1 2. Climatological data 3 3. Mountain water level data set (boreholes) 5 3.1. Station description 6 3.2. Information on the data records 6 4. Slope movement at the ravine data set (wire extensometer) 8 4.1. Station description 9 4.2. Information on the data records 10 5. References 11 1. Introduction The long time series of measurements at Eggerberg are presented here that are used in the contribution: Hormes A., Fromm R., Schönberger C., Sausgruber T., Köhler A., Stary U, Adams M., Markart G., Lienhart W., Fischer J.T (2025): Acceleration of the Gradenbach-Eggerberg rock slope deformation, Austria, in Geoenvironmental Disasters. DOI: 10.1186/s40677-025-00344-6 The Gradenbach catchment (32 km²) is located south of the Main Alpine Ridge in the Schober Group (Carinthia, Austria). It is mainly known for the large, deep-seated, and active rock slope deformation at the Eggerberg slope (Figure 1) near its mouth, which covers about 2 km² and reaches depths of over 130 m. This deformation becomes a serious threat when combined with the torrent, potentially endangering the settlement of Putschall and downstream villages in the Möll Valley (Brückl 1984, Gottschling 1999, Hagen et al. 2000, Moser et al., Weidner et al 2011). Figure 1: Deep-seated rock slope deformation at Eggerberg – approximate extent shown with dashed red line (Photo: BFW/Hagen). The dataset was manually compiled and is (partly) unprocessed, revisions are in progress. This means that small gaps in the timeseries are linearly interpolated, small data offsets can exist, outliers or other unphysical values may be still present. Note: The GNSS derived displacement data from the slope (Lienhart and Brunner 2013, Schönberger et al. 2020) is not contained in this data repository. For a quick overview of the contained data, the reader is referred to the interactive plots in the HTML files. These contain the same data as the CSV files. 2. Climatological data Climatological data presented originate from SPARTACUS v2.1 observational gridded dataset (Hiebl and Frei 2016, Hiebl and Frei 2018, GeoSphere Austria 2020)). This dataset provides daily values for air temperature (minimum temperature (TN) and maximum temperature (TX) in °C), precipitation (RR in [mm]), and absolute sunshine duration (SA) on a day-to-day basis, at a spatial resolution of one kilometer. Data on the snow water equivalent in l/m² (SWE) of the snow cover (Olefs et al. 2020) are provided by SNOWGRID-CL (SNOWGRID Climate Version V2.1, GeoSphere Austria 2022). All data are spatially interpolated to location N 47.000° E 12.853 (WGS 84, EPSG 4326) by linear means. The locatiuon corresponds to the upper part of the slide at 2023m asl. The precipitation sums RR_100 and RR_100_below_0 are derivatives based on the SPARTACUS data and defined as: ·RR_100: precipitation sum of the 100 previous days ·RR_below_0: daily precipitation of days where the sum of TN and TX doesn’t exceed 0 °C ·RR_100_below_0: precipitation sum from RR_below_0 of the 100 previous days The SPARTACUS, SNOWGRID and derivation data are found in the CSV-file: spartacus.csv The data format is a text format with a custom CSV dialect. The header consists of six rows containing meta data that are separated with an equal sign (=) from the field name, e.g.: Stationname=Spartacus V2.1 and SNOWGRID CL data and derivatives latitude=47.0 longitude=12.853 elevation=2023 nodata=-9999 unit=%Y-%m-%d;kg/m^2;s;degC;degC;kg/m^2;kg/m^2;kg/m^2;kg/m^2 Longitude and Latitude are in WGS 84 decimal system, elevation is in meters above the Adriatic (maA). The nodata field indicates a numeric NaN representation of missing values. Unit gives the printf-format for the timestamp and the SI unit for each data column. The meta data is followed by the column names, e.g.: date;SWE;SA;TN;TX;RR;RR_100;RR_below_0;RR_100_below_0 The following data block consists of semicolon separated float values with a dot as a decimal sign. The first column is the date for each row. Make sure to replace any value -9999 with NaN. 3. Mountain water level data set (boreholes) 3.1. Station description The mountain water level (MWL) was measured at several points in the area of the deep-seated mass movement at Eggerberg. The locations of boreholes 3b and 15 are shown in Figure 2, and their coordinates are listed in Table 1. Figure 2: Location of the boreholes and the extensometer (source image: KAGIS. 2025) Table 1: Properties of boreholes and Location (EPSG:4326, WGS 84) Borehole WGS 84 (EPSG:4326) altitude Pipe [m] borehole filter Name Data X Y A.s.l. [m] Over ground Depth Upper end Lower end Borehole15 MWL 12.86074 46.99285 1493 1.11 -50.0 -39.0 -49.0 Borehole3b MWL 12.85468 46.99349 1626 1.17 -45.0 -35.0 -45.0 3.2. Information on the data records Before July 2007 (borehole 3b) and August 2008 (borehole 15), MWL measurements in the boreholes were taken manually using a cable light plummet (Figure 3), which has a measuring accuracy of 1 cm. Measurements were taken approximately every 2 weeks. However, especially in the early years, the interval was inconsistent, with periods without measurement of up to one month. The resulting daily MWL values (MWLd) are linearly interpolated inbetween the manual measurements from the dataset using the formula: MWLd=DMWL / i(1) where DMWL is the difference between two MWL measurements and iis the duration between two measurements in days. Figure 3: MWL measurement with the cable light plummet (left), borehole-design (right). A column is_measurement flags whether a value is directly measured (1) or interpolated (0). Interpolated values were identified by analyzing the change in daily MWL differences (i.e., the difference of consecutive daily changes, with units mm/day²). When this change in daily differences was below 0.1 mm/day², the value was assumed to be interpolated. Days with larger changes were considered to correspond to actual manual measurements. A notable data gap exists between 1 February 1996 and 7 October 1998 due to a lack of manual recordings. Since July 2007 (borehole 3b) and August 2008 (borehole 15) measurements have been recorded automatically using an OTT Orpheus Mini pressure probe with an integrated temperature sensor and data logger. Again, some smaller data gaps are filled via interpolation, and those gaps are indentified in the same logic as for the manual measurements. The data for boreholes 3b and 15 used in the publication are found in the files: borehole3b.csv and borehole15.csv respectively. The data format is a text format with a custom CSV dialect. The header consists of six rows containing meta data that are separated with an equal sign (=) from the field name, e.g.: Stationname=MWL at borehole 15/3b latitude=46.99285 longitude=12.86074 elevation=1493 nodata=-9999 unit=%Y-%m-%d;m;0/1 Longitude and Latitude are in WGS84 decimal system, elevation is in maA. The nodata field indicates a numeric NaN representation of missing values. Unit gives the printf-format for the timestamp and the SI unit for each data column. The meta data is followed by the column names, e.g.: date;MWL_bl3b;is_measurement The last collum “is_measurement” indicates if the value is interpolated (0) or a true measurement (1). The following data block consists of semicolon separated float values with a dot as a decimal sign. The first column is the date for each row. Make sure to replace any value -9999 with NaN. 4. Slope movement at the ravine data set (wire extensometer) 4.1. Station description At the Gradenbach ravine, the convergence between the foot of the mass movement and the relatively stable rock mass on the opposite valley side was monitored by the BFW using two wire extensometers (location Figure 2, Table 2). However, one was destroyed after a few years; thus, only data from the still existing extensometer is provided here. The wires span approximately 50 meters (Figure 4, Figure 5). Important note: The time series indicated a continuous recording over a large data gap between 1996 and 1998. It is implausible that the slope did not move during this period and any analysis should treat the data as two separate measurements: until 1996 and after 1998! We keep the data as provided to be consistent with the Publikation Hormes, 2025. Figure 4: Wire extensometer at the Gradenbach ravine (Photo: BFW/Hagen). Table 2: Location of the wire extensometer (EPSG4326, WGS 84). Name X Y Altitude Wire extensometer 12.862327 46.986815 1200 Figure 5: Wire extensometer registration at Gradenbach,; strip chart recorder and digital recording (Thalimedes). 4.2. Information on the data records Observations started in 1979 and ended in 2023, with a gap between 1996 and 1998. The analogue readings with a strip chart recorder were manually digitized with an approximate accuracy of 2.5mm. The analogue readings were manually digitized. In 2006, the wire extensometer was upgraded with a continuous electronic recording system (Thalimedes, see Figure 5), which records data with a resolution of 1mm. The temporal resolution of the data until 2006 is daily and hourly afterwards. However, to minimize the influence of temperature and solar radiation—which cause expansion and contraction of the metal wire—only daily values of the distance are provided. Additionally, daily velocities over the past 10 days in meters per 10 days are calculated to reduce the scatter of the movement values. Like the interpolated borehole data, a boolean indication whether a measurement has been interpolated or truly recorded is stored in the columns “is_measurement”. Interpolated values were identified by analyzing the change in daily distances (i.e., the difference of consecutive daily changes, with units m/day²). When this change in daily differences was below 0.01 mm/day², the value was assumed to be interpolated. Days with larger changes were considered to correspond to actual measurements. The Extensometer data used in the publication is found in the file: extensometer.csv The data format is a text format with a custom CSV dialect. The header consists of six rows containing meta data that are separated with an equal sign (=) from the field name, e.g.: Stationname=Wire Extensometer latitude= 12.862327 longitude= 46.986815 elevation=1200 nodata=-9999 unit=%Y-%m-%d;m;m/10d;1/0 Longitude and Latitude are in WGS84 decimal system, elevation is in maA. The nodata field indicates a numeric NaN representation of missing values. Unit gives the printf-format for the timestamp and the SI unit for each data column. The meta data is followed by the column names, e.g.: date;distance;velocity;is_measurement The following data block consists of semicolon separated float values with a dot as a decimal sign. The first column is the date for each row. Make sure to replace any value -9999 with NaN.