Vojtěch Beneš | Charles University, Prague (original) (raw)

Papers by Vojtěch Beneš

Ecology and the Environment, Aug 18, 2009

The Geophysical Monitoring System (GMS) has been designed as a new instrument for maintenance of ... more The Geophysical Monitoring System (GMS) has been designed as a new instrument for maintenance of and checks on safety of flood control dikes in the Czech Republic. Having used the new tool to define hot spots of an existing embankment system, detailed investigation, maintenance and renewal efforts can be concentrated in a cost-effective way on the critical parts of the embankments. Based on the analysis of geophysical measurements carried out on the dikes and based on the discussion with the dike owners/caretakers representatives it can be stated that for maintenance and check of the dikes there are 3 basic types of tasks that can be effectively covered using geophysical methods. The first task includes a survey of long embankment sections (Quick Testing Measure), the second refers to detailed investigation of problem sections and the third one aims at providing basic data for classification and a geomechanical description of the dikes material. The GMS comes with special software-GIH 01. This GIH01 tool is a light version of software for geophysical inspection of the dams and it is being developed and tested within research projects financed by the Ministry of Industry and Trade of the Czech Republic: "Research and development of the modular system GIH 01 for applications for Integrated Water Resources Management in the catchment scale and floods prevention". Thanks to the GMS control method and GIH 01 data evaluation and visualization it is possible to design the optimal process of dike reconstruction and protection within the entire river basin areas.

Science and practice for an uncertain future, 2021

The aim of this paper is to describe an innovation in the monitoring of performance of earth emba... more The aim of this paper is to describe an innovation in the monitoring of performance of earth embankments, namely the use of sensing systems for full-time monitoring of ash pond and irrigation pond seepages. In the past decades, due to IT development and cost reduction, the sensor technology segment and associated measurement and monitoring systems have started to expand rapidly. One of the areas of sensor technology suitable for real-time monitoring of earthen embankments is that of fibre optic distributed temperature sensors (FO DTS). This paper deals with the results of pilot measurements performed within the E!11705 FORMTES project in 2018-2020, as related to the analysis of the existing FO DTS system installed in the irrigation pond in Spain, and on the new implementation of the FO DTS system in part of the embankment of the ash pond in Hungary, and the use of FO DTS systems for monitoring of potential seepage in above mentioned embankment structures. The evaluated pilot tests together with the desk review were used for the validation and enhancement of the novel methodology to enable its real-life implementation both for the existing embankment structures and the development of detailed designs of new structures of similar nature.

More than 500,000 km of embankment are used in Europe for transport and flood defence, representi... more More than 500,000 km of embankment are used in Europe for transport and flood defence, representing a 1bn infrastructure asset base, which supports and protects the economy of Europe (e.g. property worth some 2,000 bn is protected from flooding.) Presently the state and performance of these embankments can only be investigated visually or by slow intrusive methods (boreholes etc.) Potential now exists to apply a geophysical investigation tool, originally developed for military applications, for rapid non-intrusive identification of hot spots of deterioration in embankments. Better targeting of maintenance interventions using this approach will achieve substantial whole-life cost savings and avoid failures costly for the economy and society. Geophysical investigation involves generating electro-magnetic fields and mapping their propagation through soils and structures. The method finds perturbations in the electro-magnetic fields arising from concealed boundaries or changed mat...

Morphology of the halfblind Hostěnice Valley was established based on electric resistivity soundi... more Morphology of the halfblind Hostěnice Valley was established based on electric resistivity sounding and seismic measurements. A limestone bottom of the valley is situated at altitude 350 m a.s.l bellow ca. 30 m thick fluvial or lacustrine clayey and sandy deposits. At the limestone and non-karstic boundary a 20 m high step was formed. The bottom of the valley (350 m a.s.l.) corresponds with the older cave corridors in the nearby Ochozska Cave forming probably Pliocene cave level. During the Quaternary main cave passages were deepened leaving the older corridors in a hanging position.

Acknowledgements: Created with support of Czech development cooperation projects 194/07-09/MŽP/B ... more Acknowledgements: Created with support of Czech development cooperation projects 194/07-09/MŽP/B (RP/27/2004) „Monitoring of high mountain glacial lakes and protection of the population against catastrophic impacts of floods from moraine lake outbursts“, and RP/9/2007: “Analysis of the risk of failure of alpine lake dams and the mitigation of the consequent impacts; Kyrgyz Republic”, NATO CLG project “Glacier hazards in Kyrgyzstan: implications for resource development and water security in Central Asia” and GA UK project no. 619112 “Risk analysis of glacial outburst lakes in Adygine area (Tien Shan Mts, Kyrgyzstan)”. Our thanks belongs to Tomáš Hrdinka, Václav Mašek who helped with field measurements.  Territory

Physics and Chemistry of the Earth, Parts A/B/C, 2020

Stability of flood embankments is strongly affected by the water flow taking place in the saturat... more Stability of flood embankments is strongly affected by the water flow taking place in the saturated and unsaturated soil. Monitoring of the water flow in flood embankments is therefore essential in the context of flood risk management to predict and prevent failures of embankments. Electrical Resistivity Tomography (ERT) is gaining popularity for its ability to monitor water regime in the subsoil more quickly, cost-effectively and on a larger scale compared to traditional geotechnical monitoring systems that rely on local sensors. This paper presents the application of ERT to the monitoring of water content in a flood embankment on the Adige River in Italy. The resistivity profiles obtained from the ERT measurements were converted into water content profiles via a laboratory-derived relationship between resistivity and water content. At the same time, local sensors to monitor pore water pressure were installed in the saturated and unsaturated zone of the embankment and this allowed reconstructing the water content regime in the embankment via inverse analysis of water flow. This offered the chance to benchmark ERT-derived water content against independent indirect measurements of water content in the field. ERT-inferred water content profiles based on laboratory calibration could capture the water content profiles derived from water flow analysis only qualitatively. This was attributed to artefacts in the ERT data inversion arising from the high contrasts in resistivity between different embankment layers. On the other hand, ERT proved to be a valuable tool to quantify the water content in the soil if field-specific relationship between water content and ERTmeasured resistivity is developed.

Acta Carsologica, 2016

UDC: 551.44(55+437.1) Pavel Bosák & Vojtìch Beneš: Geophysical characteristics of epikarst: case ... more UDC: 551.44(55+437.1) Pavel Bosák & Vojtìch Beneš: Geophysical characteristics of epikarst: case studies from Zagros Mts. (Iran) and the Konìprusy region (Czech Republic) Characteristics of epikarst zone were studied by geophysical methods, especially refraction seismics, combined with electrical resistivity and gravimetry measurements. Applied methods were equal in both regions, so comparable results were obtained. The interpreted seismic boundaries follow the basal plane of epikarst (s.l.) and limit the epikarst zone from the geophysical point of view, i.e. zone with comparably low seismic velocities (mostly 1,000 to 3,000 m.s-1). The thickness of epikarst in the Czech Karst-the Konìprusy Devonian-is from 5 to about 60 m. The epikarst in Zagros Mts. reached up to 180 m (Cretaceous lmst.). The differences of character and vertical extent of epikarst zone depend on entirely different geological structure and geomorphological setting (relief) and evolution of both sites, which established different conditions for the release of residual stress in the limestone massifs.

Earth Surface Dynamics Discussions, 2018

Formation and development of glacial lakes in mountain regions is one of the consequences of glac... more Formation and development of glacial lakes in mountain regions is one of the consequences of glacier recession. Such lakes may drain partially or completely when the stability of their dam is disturbed. We presented a case study from Central-Asian mountain range of Tien Shan, a north-oriented tributary valley Adygine, where a glacier retreat resulted in formation of several generations of lakes. The aim of this study was to analyse past development of different types of glacial lakes influenced by the same glacier, to project site's future development, and to evaluate the hazard of individual lakes with an outlook for expected future change. We addressed the problem with a combination of methods, namely bathymetric, geodetic, and geophysical on-site survey, satellite image and DEM analysis, and modelling of glacier runoff evolution. Based on the case of glacial lakes of varied age and type, we demonstrate the significance of glacier ice in lake's development. Lake 3, which is in contact with glacier terminus, has changed rapidly over the last decade, expanding both in area and depth and increasing its volume more than 13 times (7 800 m 3 to 106 000 m 3). Hydrological connections and routing of glacier meltwater proved to be an important factor as well, since most lakes in the region are drained by subsurface channels. Within the hazard evaluation of lakes, we highlighted the importance of field data which can provide crucial information on lake stability. In our case, the understanding of site's hydrological system and its regime helped to categorise Lake 2 into low outburst hazard, while Lake 1 and Lake 3 were labelled as medium hazard lakes. Further development of the site will be driven mainly by rising air temperature and increasingly negative glacier mass balance. All three scenarios predict a significant glacier area decrease by 2050, specifically leaving 73.2 % (A1B), 62.3 % (A2), and 55.6 % (B1) of the 2012 glacier extent. The glacier retreat will be accompanied by changes in glacier runoff with first peak expected around the year 2020. 1 Introduction Glacial lakes can be seen as gems gleaming in the harsh mountain environment. However, at the same time, they can pose a serious threat to downstream settlements and infrastructure. If we focus on Asian mountain ranges, the now common term GLOF (glacial lake outburst flood), first used for the Himalayan region, is ubiquitous. Mainly due to the development of satellite-based sensor technologies, the areas under scrutiny of investigators have increased from the Himalayas (Benn et al.,

E3S Web of Conferences, 2016

The paper presents results achieved within the project MAGIC, a project funded by the European Co... more The paper presents results achieved within the project MAGIC, a project funded by the European Commission under the Marie-Curie Industry Academia Partnerships and Pathways (IAPP) scheme. The project MAGIC aims to advance the state-of-the art in the monitoring of geo-structures subjected to climate loading by filling some of the gaps in current monitoring technologies. The project involves a partnership between academic and industrial partners to boost knowledge transfer and promote the development of 'industrial' instruments and services. The paper presents developments concerning the measurement of pore-water tension (suction in excess of 100 kPa) and the integration of geotechnical and geophysical monitoring.

Natural Hazards, 2008

An interdisciplinary study of glacier-related hazards in the Petrov lake region (Ak-Shiirak Range... more An interdisciplinary study of glacier-related hazards in the Petrov lake region (Ak-Shiirak Range, the Inner Tien-Shan, Kyrgyzstan) has been undertaken to identify potential dangers to the area. A cooperative effort from experts in the fields of hydrology, glaciology, geomorphology and geophysics has been employed in this study. For the hazard assessment, evolution of the Petrov glacier and lake was reconstructed using historical reports, aerial photographs and satellite images. Geomorphological mapping and geophysical soundings was applied to the lake territory and the moraine dam. This has identified potentially hazardous areas of the dam including subsurface drainage zones and cracks that could cause a sudden extremely high discharge. In the past three decades, the Petrov lake has doubled in size, while in recent years, its area has been increasing by more than 92,000 square metres per year. Although there is no evidence for an imminent outburst, the dramatic increase in the lake's size emphasizes the importance of this study.

Acta Musei Moraviae, …, 2001

Geological Society, London, Special Publications, 2018

Geophysical electrical resistivity tomography (ERT) is a promising measurement technique for non-... more Geophysical electrical resistivity tomography (ERT) is a promising measurement technique for non-intrusive monitoring of an engineered barrier system (EBS) during the operational phase of geological disposal of high-level radioactive waste. Electrical resistivity is sensitive to water content and temperature, which are the key variables characterizing the response of the EBS. In order to assess the technology readiness level of the ERT technique for EBS operational monitoring, a field demonstrator has been developed at the underground research laboratory (URL) in Tournemire (France) within the project ‘Modern 2020’. Preliminary ERT surveys were carried out in January and November 2017 to establish the background resistivity of the experimental area and assess the quality of electrode installation and survey protocols. Results of the surveys confirmed that the resistivity of the host rock in the demonstrator area is quite homogenous and lower than 100 Ωm in accordance with independen...

The floodplain of the lower course of the Morava River in the Straznicke Pomoravi area located in... more The floodplain of the lower course of the Morava River in the Straznicke Pomoravi area located in the Lower Moravian Basin is an excellent example of an environmental archive of which a detailed study could help understanding of the interplay between regional environmental changes, global climatic changes and human activities. The length of the meandering course of the Morava River

Geomorphology, 2014

ABSTRACT Late Pleistocene to Holocene Morava River valley-fill of the eastern Czech Republic refl... more ABSTRACT Late Pleistocene to Holocene Morava River valley-fill of the eastern Czech Republic reflects the geomorphic evolution of the valley as forced by climate change. Valley-fill stratigraphy was studied through measured sections, optically stimulated luminescence (OSL) and radiocarbon dating, ground-penetrating radar surveys of relict sand dunes, archived drill-hole data, and a comparison of elevations and ages of stratigraphic units. Fluvial systems evolved from meandering with floodplains to braided during MIS 3. Braided fluvio-aeolian systems dominated through MIS 2 and the Last Glacial Maximum (LGM). Valley aggradation occurred during arid glacial times of a low water-to-sediment discharge ratio. Most valley-fill was removed at 13 ka with incision by a large-bend meandering river with an estimated bankful paleodischarge 3 × larger than the modern Morava River. The Holocene Morava River has varied from meandering to anabranching with low rates of floodplain aggradation. The Bzenec sand body, up to 36 m thick, represents an erosional remnant bypassed during late Pleistocene incision and consists of interpreted lacustrine turbidites overlain by braided stream and aeolian dune strata. The turbidites consist of laterally continuous, thin, normally graded beds of rounded and frosted sand grains of aeolian origin. Dates and elevation data argue that the valley lake formed during the LGM through downstream damming by a braided terminal fan and sand dune complex. The turbidites are interpreted to have formed through fluvial undercutting and slumping of dune accumulations as lake level rose. This process forced an erosional unroofing of aeolian accumulations, reflected in inverted OSL dates for the turbidites.

Natural Hazards, 2009