Towards hydrological triggering mechanisms of large deep-seated landslides

It is a widely accepted idea that hydrologically triggered deep-seated landslides are initiated by an increase in pore-water pressure on potential slip surface induced by rising groundwater level after prolonged period of intense rainfall although the process is not fully understood. In order to contribute to better understanding, the rainfall–groundwater relationships, hydrogeological monitoring and repeated geoelectrical imaging were carried out from March 2007 to April 2011 in large deep-seated landslide near ?ubietová (Western Carpathians) catastrophically reactivated at the end of February 1977. Based on our observations, groundwater level (GWL) response to precipitation differs considerably with respect to both overall hydrological conditions and GWL mean depth. While the rate of GWL increase up to 25 cm/day were measured after some rainfall events during wet periods, noticeably lower recharge rate (up to 1–2 cm/day) and delayed GWL response to rainfall (usually from 2 weeks to 2–4 months) were observed at the beginning of the wet season after considerable depression of GWLs due to previous effective rainfall deficit. Likewise, slow GWL fluctuations without short-term oscillations are typical for deeper GWLs. Thus, long-term (several seasons to several years) hydrological conditions affect markedly groundwater response to rainfall events in the studied landslide and can be crucial for its behaviour. Comparison of hydrological conditions characterising the analysed period with those that accompanied the landslide reactivation in 1977 allow us to assume that slightly above-average rainy season following the prolonged wet period can be far more responsible for movement acceleration (and possibly failure initiation) in deep landslides than the isolated season of extreme precipitation following a longer dry period. This is true especially for landslides in regions with significant seasonal temperature changes where potential effective precipitation (PEP), calculated as excess of precipitation (P) over potential evapotranspiration (PET), may be efficiently used for estimation of slope saturation condition.     

Exploratory analysis of paleoecological data using the program CanoDraw

This paper attempts to persuade the reader that methods of direct gradient analysis may serve as a basis for more detailed exploration of the data and that these exploration methods can be also used for checking the appropriateness of the assumptions of the applied ordination method. Generalized linear models and generalized loess smoothing together with several ways of data presentation are used to explore a sample data set.     

Importance of borehole deviation surveys for monitoring of hydraulic fracturing treatments

During seismic monitoring of hydraulic fracturing treatment, it is very common to ignore the deviations of the monitoring or treatment wells from their assumed positions. For example, a well is assumed to be perfectly vertical, but in fact, it deviates from verticality. This can lead to significant errors in the observed azimuth and other parameters of the monitored fracture‐system geometry derived from microseismic event locations. For common hydraulic fracturing geometries, a 2° deviation uncertainty on the positions of the monitoring or treatment well survey can cause a more than 20° uncertainty of the inverted fracture azimuths. Furthermore, if the positions of both the injection point and the receiver array are not known accurately and the velocity model is adjusted to locate perforations on the assumed positions, several‐millisecond discrepancies between measured and modeled SH‐P traveltime differences may appear along the receiver array. These traveltime discrepancies may then be misinterpreted as an effect of anisotropy, and the use of such anisotropic model may lead to the mislocation of the detected fracture system. The uncertainty of the relative positions between the monitoring and treatment wells can have a cumulative, nonlinear effect on inverted fracture parameters. We show that incorporation of borehole deviation surveys allows reasonably accurate positioning of the microseismic events. In this study, we concentrate on the effects of horizontal uncertainties of receiver and perforation positions. Understanding them is sufficient for treatment of vertical wells, and also necessary for horizontal wells.     

The Žermanice sill: new insights into the mineralogy,petrology, age,and origin of the teschenite association rocks in the Western Carpathians,Czech Republic

International Journal of Earth Sciences - The Žermanice locality represents the best-exposed example of the meta-basaltoid/meta-gabbroic rock type of the teschenite association. It forms a...     

Inverse modeling of natural tracer transport in a granite massif with lumped-parameter and physically based models: case study of a tunnel in Czechia

This study deals with numerical modelling of hydraulic and transport phenomena in granite of the Bohemian massif in Bedrichov, Czechia (Czech Republic). Natural tracers represented by stable isotopes δ¹⁸O and δ²H were collected at the tunnel outflow points and nearby catchment and their concentrations were monitored for seven years. The study compared transport simulations by a two-dimensional (2D) physically based model (advection-dispersion) developed in Flow123d software and a simpler lumped-parameter model, calculated with FLOWPC. Both variants were calibrated with UCODE software, either fitting the concentration data alone, or including the tunnel inflow rates in the case of the 2D model calibration (either in separate steps or within a single optimization problem). Since each of the models describes the tracer transport with different parameters, the models were compared based on the mean transit time as a postprocessed quantity. Besides this, two different options for processing the recharge data (input for both models) were evaluated. Calibration and data interpretation were possible for three of the four observed places in the tunnel, thus determining the depth limit of applicability of the stable isotopes. The estimates for discharge sampling at 25–35 m depth based on inverse modelling provide reasonable values of mean transit time (20–40 months) for the lumped parameter models, little revising the results of previous studies at the site. The resulting transport parameters of the advection-dispersion model (porosity and dispersivity) are in accordance with the hydrogeological structures present at the sampling sites.

     

The stratigraphic and paleoenvironmental setting of Aptian OAE black shale deposits in the Pieniny Klippen Belt, Slovak Western Carpathians

During the Jurassic and Cretaceous, the Pieniny Klippen Belt units of the Outer Western Carpathians were situated on the edge of the Paleoeuropean shelf rimming the northermost margin of the Mediterranean Tethys. During the late early Aptian humid event, Lower Cretaceous pelagic carbonate (Maiolica) sedimentation was interrupted by terrigenous input as a consequence of the first major mid-Cretaceous climate perturbations. The fluctuation of radiolarian abundance indicated an expansion of the oxygen-minimum zone due to upwelling conditions and salinity changes. Foraminifera, radiolarians, non-calcareous dinocysts, and calcareous nannofossils encountered in the West Carpathian Rochovica section enable a comparison of the black shales of the upper lower Aptian Koňhora Formation with the well-known Selli Event. Subsequent anoxia patterns (depositional, productive, and stagnant) have taken part in the depositional regime. Early Aptian climate perturbations both in the Outer Western Carpathians, Swiss Prealps (situated in a similar position on the distal southern edge of the former Paleoeuropean shelf) and/or in other parts of the world are traceable with sedimentological, biological, and chemical proxies.     

An unsustainable state: Contrasting food practices and state policies in the Czech Republic

This paper brings together consideration of food policies and practices and of post-socialist transition to raise neglected questions about means of nurturing more sustainable food systems in the developed world. The last three decades have been marked by the growing salience of food as a political and scholarly concern. While market-based alternative food systems have been heralded for their potential to promote environmental sustainability, the benefits of non-market practices such as household food self-provisioning and barter have been assumed rather than being the focus of research. In the western context, both types of food consumption have positive connotations. Although food self-provisioning in European post-socialist societies is a more wide-spread practice than in western societies, it has been on the periphery of research. The existing literature has conceptualised them as ‘coping strategies’ or as a legacy of irregular supply of goods in the state socialist era. Drawing on empirical research in the Czech Republic, we are proposing a novel approach to the phenomenon of household food production in post-socialist societies as a practice compliant with principles of sustainability. First, we highlight the large extent and social inclusivity of food self-provisioning in Czech society to demonstrate how post-socialist societies are a repository of a rich set of sustainability-promoting consumption practices in relation to food systems. Second, we show that international and domestic policy actors in these societies have ignored these alternative, socially inclusive and environmentally effective practices in favour of far less effective market-based sustainability oriented food policy initiatives. The paper promotes a more integrated view of non-market and market approaches in the pursuit of more sustainable food systems.