Filip Hartvich

The monitoring of slow-moving landslides and assessment of stabilisation measures using an optical–mechanical crack gauge

It is possible to monitor slow-moving landslides and assess landslide stabilisation measures over protracted periods using an optical–mechanical crack gauge called a TM-71. This technical note outlines the theoretical background to the gauge and illustrates its practical application through a number of case studies. These studies are drawn from a range of landslide types and stabilisation measures. In terms of monitoring slow-moving landslides, three studies of deep-seated deformations are presented. The Taukliman coastal landslide on the Black Sea Coast is characterised by vertical and horizontal displacements of up to 0.2xa0mmxa0year−1 and sudden earthquake-induced dilations of up to 6xa0mm. The Parohy ridge spreading landslide in the Malá Fatra Mountains is characterised by gravitationally induced vertical displacements of 0.7xa0mmxa0year−1. The slope deformation that formed Cyrilka Cave in the Beskydy Mountains is characterised by very slow sinistral strike–slip movements of 0.8xa0mmxa0year−1. In terms of assessing landslide stabilisation measures, two studies are presented from Orava Castle in Slovakia and Tetín in the Czech Republic. The data recorded at these sites demonstrate that the constructed stabilisation measures have successfully alleviated the potential landslide hazard in both localities. These case studies clearly demonstrate that the gauge represents an important tool with which to monitor slow-moving landslides and assess landslide stabilisation measures. It is able to provide a precise three-dimensional record of deformation, withstand harsh environmental conditions, and record reliable data over protracted periods.

The variability of surface water quality indicators in relation to watercourse typology, Czech Republic

This paper examines the relationships between watercourse typology and selected indicators of long-term surface water quality for rivers in the Czech Republic. The parameters used to define watercourse typology are in accord with the Water Framework Directive 2000/60/EC outlined by the European Commission. The relationships were tested using descriptive and multivariate statistical analysis, namely cluster analysis and canonical correspondence analysis. It was found that only some of the typological parameters have a close association with indicators of surface water quality. Specifically, the parameters of altitude and geology show clear relationships with pH, calcium content, and the saprobity index of macroinvertebrates. Conversely, parameters that are strongly influenced by anthropogenic pollution show weak relationships with indicators of surface water quality. These depend instead on the presence of pollution sources rather than on natural environmental conditions.

Landslides in moraines as triggers of glacial lake outburst floods: example from Palcacocha Lake (Cordillera Blanca, Peru)

Studies focusing on moraine deposits which slide into glacial lakes are scarce, even though they can trigger impact waves responsible for generating glacial lake outburst floods. We focused on landslides in lateral moraines as possible triggers. Detailed geomorphological, geophysical, and satellite radar interferometric investigations of the Palcacocha Lake moraine (Cordillera Blanca, Peru) together with laboratory tests on samples from the site provided data for slope stability calculations using GeoSlope software and hydrodynamic impact wave modeling using the Iber code. We identified landslides that could affect Palcacocha Lake and calculated their stability (factor of safety) under specified conditions, including variable water saturation and earthquake effects. Calculations showed that the moraine slopes are close to the threshold value (Fsu2009=u20091) for stability and are especially sensitive to water saturation. The height of impact waves triggered by a landslide in 2003 and the potential wave heights from newly identified, possibly active landslides were calculated, based on landslide volume estimates, detailed lake bathymetry, and basin topography. Results show that potential future landslide-triggered waves could have similar properties to the 2003 impact wave. Evidence gathered in this study suggests that glacial lake outburst floods triggered by landslides from moraines, however, would be probably smaller than floods resulting from other types of slope processes (e.g., ice/rock avalanches) if dam breach is not taken into account. This assumption has to be critically evaluated against site-specific conditions at a given lake and any possible environmental factors, such as climate change or earthquake that may mobilize larger volumes of moraine material.

Tracing an Intra-montane Fault: An Interdisciplinary Approach

This paper presents the results of combined geophysical and morphostructural research of a significant tectonic lineament forming the boundary between the core Bohemian Forest (Šumava) Mts. and its foothills of Pošumaví. The exact course, length and character of the fault have not yet been studied in detail despite its possible role in the uplift of the mountain range. To assess the fault course, length and continuity, we have employed a combination of geophysical, morphological and morphostructural methods. These indirect methods had to be applied as the fault only rarely outcrops along its course, and the morphological border is not straightforward. In the beginning, GIS morphometric methods have been applied to assess the influence of the fault on the present relief. Thereafter, structural measurements of joint systems were undertaken together with the analyses of linear structures within the relief. Finally, resistivity profiling at multiple sites across its estimated course has helped to localise the exact position of the fault. Altogether, fifteen profiles were measured using pole-dipole and dipole–dipole electrode configurations. To obtain more detailed results, the resistivity profiling was supplemented by electrical resistivity tomography on three profiles. The paper brings two main results. Firstly, the combination of morphostructural and geophysical methods brings information that each separately cannot, particularly when the faults have no outcrops. Secondly, it was found that the studied fault stretches along the whole study area. Moreover, indicators point to its possible continuation towards the south-east.

UAV-Based Optical Granulometry as Tool for Detecting Changes in Structure of Flood Depositions

This paper presents a new non-invasive technique of granulometric analysis based on the fusion of two imaging techniques, Unmanned Aerial Vehicles (UAV)-based photogrammetry and optical digital granulometry. This newly proposed technique produces seamless coverage of a study site in order to analyze the granulometric properties of alluvium and observe its spatiotemporal changes. This proposed technique is tested by observing changes along the point bar of a mid-latitude mountain stream. UAV photogrammetry acquired at a low-level flight altitude (at a height of 8 m) is used to acquire ultra-high resolution orthoimages to build high-precision digital terrain models (DTMs). These orthoimages are covered by a regular virtual grid, and the granulometric properties of the grid fields are analyzed using the digital optical granulometric tool BaseGrain. This tested framework demonstrates the applicability of the proposed method for granulometric analysis, which yields accuracy comparable to that of traditional field optical granulometry. The seamless nature of this method further enables researchers to study the spatial distribution of granulometric properties across multiple study sites, as well as to analyze multitemporal changes using repeated imaging.

Large Late Pleistocene landslides from the marginal slope of the Flysch Carpathians

The gently concave piedmont of the marginal slope of the Flysch Carpathians in the Czech Republic has long been considered to comprise a system of pediments or coalescent alluvial fans. However, within one of the typical sections of this piedmont, large successive landslides with long travel distances of ~2.5xa0km have been identified through geophysical measurements and the investigation of an extensive artificial exposure. Accelerator mass spectrometry (AMS) radiocarbon dating and pollen analysis demonstrate that the uppermost generations of landslide deposits have originated since ~56xa0ka BP during the warmer and more humid interpleniglacial conditions of Marine Isotope Stage 3 (MIS 3). The geomorphological evidence for landsliding during MIS 3 has almost completely disappeared from this region due to intensive periglacial processes operating during the Last Glacial Maximum and subsequent fluvial and anthropogenic processes operating during the Holocene. The considerable antiquity of the studied terrestrial landslide bodies is unique within the context of Europe. This study shows the value of re-examining landscape development using new techniques and fresh exposures.

Challenges for landslide hazard and risk management in ‘low-risk’ regions, Czech Republic—landslide occurrences and related costs (IPL project no. 197)

The presented work was performed within the scope of the IPL project no. 197, entitled ‘Low frequency, highly damaging potential landslide events in ‘low-risk’ regions – challenges for hazard and risk management’. The Czech Republic is an example of a landslide ‘low-risk’ country with all the related challenges for long-term and sustainable landslide risk management. We argue that the main challenge is to raise and maintain a corresponding level of public attention to landslide hazards and risks. Since hazard and risk recognition by the potentially affected people is the main precondition of any effective risk mitigation, we performed several tasks to provide as yet unavailable information about specific aspects of the occurrence of landslides in the Czech Republic which may attract the attention of the public, including the responsible authorities, to the landslide risk. These aspects include new ways of updating a landslide inventory and compilation of a database of the cost of landslide mitigation works paid by the government. Landslide inventories derived from web sources, the unified system of traffic information of the national road authority and information collected by the Czech Geological Survey were compared. The landslide inventory compiled by the Czech Geological Survey is the most complete, but in some cases, the other two inventories could be used to complete it with landslide events not yet registered. Landslide-related expenses of the state budget are not negligible and their uneven spatial distribution cannot be explained by landslide occurrences only, which calls for in-depth risk assessment.

Studies on selected landslides and their societal impacts: activity report of the Prague World Centre of Excellence, Czech Republic

Research and dissemination activities of the World Centre of Excellence on Landslide Risk Reduction (WCoE), located in Prague, Czech Republic, entitled “Landslide risk assessment and development guidelines for effective risk reduction” focus on the strengthening of landslide risk reduction efforts defined through the Sendai partnership and the International Program on Landslides (IPL). WCoE’s contribution to this objective is represented mainly by long-term landslide monitoring, site-specific, and regional hazard assessment as well as a variety of dissemination activities targeting the general public and those involved in landslide risk management. Apart from the Czech Republic and Slovakia, research was performed in the regions where landslides may have considerable negative impacts on society (e.g., South America, Africa) or where landslide processes may be significantly enhanced by climate change (arctic regions and high, glaciated mountains).

The 2002 flood consequences in the catchment of Otava River, Czech Republic

In this article we analyse and compare the data on consequences of the catastrophic 2002 floods in two subcatchments of Otava river basin collected during specialized mapping in 2003. The Otava River is situated in the southwest of the Czech Republic. From its basin we have chosen two different subcatchments: Lower Otava River, surrounded by flat, lowland landscape and Losenice River, swift stream descending from the Sumava Mountains. We also present some basic data on the flood course and its hydrological parameters and meteorological causes.

Landslide Hazard and Risk Management (WCoE 2014–2017)Open image in new window

The World Centre of Excellence (WCoE) on Landslide Risk Reduction entitled “Landslide risk assessment and development guidelines for effective risk reduction” (2014–2017) was designed to contribute to the risk reduction effort formulated in the Sendai Partnership initiative. Several research activities were developed and their results were presented to a broad public through a series of articles, informative web pages and documentary movies. The research focused on improving landslide hazard assessment in a variety of natural environments, including deep-seated as well as shallow landslides. Landslide hazard assessment was applied practically through development projects in Ethiopia and Peru. Within the scope of the WCoE we proposed and conducted two projects of the International Program on Landslides (IPL). One of them is dedicated to compilation and analysis of glacial lake outburst floods (Database of glacial lake outburst floods (GLOFs)–project No. 179) at the global level. This potentially highly damaging natural phenomenon combines characteristics of floods and debris flows and often also involves landslides in the initiation process. The other IPL project focuses on the main challenges of landslide risk reduction in the Czech Republic (Challenges for landslide hazard and risk management in “low risk” regions, Czech Republic, IPL project No. 197), which is a country with abundant landslide-related knowledge and rather low annual occurrence frequencies. Despite that, landslides cause considerable damage and financial losses, which often could be prevented if the available hazard information were to be used.