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Nechyba M.,GEO TOOLS | Varilova Z.,GEO TOOLS | Kotva P.,GEO TOOLS | Kotva P.,Municipal Museum of Usti Nad Labem | And 2 more authors.
Acta Universitatis Carolinae, Geographica | Year: 2016

The Ethiopian Plateau and the Rift Valley typically display various symptoms of intensive erosion, mass movement and land degradation, which have arisen in response to rapid changes in land cover in an area of high dynamics of relief development. In order to assess the risk of these symptoms of intensive erosion and mass movement it is necessary to apply a method for the evaluation of non-linear systems. Therefore, our aim was to develop a combined method for evaluating the risk of landslides or erosion using complex system theory. This combined integrated method has been tested on two selected localities with landslide hazards on the border of the Ethiopian Highlands and the Main Ethiopian Rift. The method is suitable for a prompt risk evaluation and swift decision making.

Varilova Z.,Bohemian Switzerland National Park Administration | Zvelebil J.,Geo Tools | Palus M.,Institute of Computer Science
Landslides | Year: 2011

Ever wider implementation of information technologies is flooding us by monitoring data. To an efficient risk management, those data have to be processed and assessed in the same rate as they are recorded and transported. Paper demonstrates some methods dealing with intrinsic, nonlinear dynamics of slope system for computerized safety assessment of monitoring time series, their modeling and early warning launching. Analysis and modeling of phase changes - i. e. specific transient states between different developmental stages of dynamics of unstable slope systems, enabled to fix new types of precursors for rock fall warning and to enhance time prediction of rock fall occurrence. Mathematically well based, novel numerical and topological methods from the toolbox of complex system theory were successfully implemented to that challenge. Their pattern-recognition ability, i. e., diagnostic sensitivity, and more realistic results of modeling of time series relevant patterns have reached beyond ranges of regularly used-both the idea- and the data-driven-methods. Moreover, results yielded by phase space analyses are in good agreement with the ones by numerical fractal analyses. Obtained results have strengthened the primary, mainly theoretically based hypothesis; the dynamics of an unstable rock slope has to be considered as behavior of nonlinear, dissipative, non-equilibrium, self-organizing complex system. Correspondingly to the theoretical assumptions, two qualitatively different types of slope system dynamics-near to equilibrium and far from equilibrium states, were identified. All field monitoring data used originated in practice of highly automated, integrated IT system of monitoring assessment, and management of rock fall hazard at sandstone rock walls in the NW Bohemia. © 2010 Springer-Verlag.

Varilova Z.,GEO TOOLS | Varilova Z.,The Museum of the City of Usti nad Labem | Kropacek J.,University of Tübingen | Zvelebil J.,GEO TOOLS | And 2 more authors.
Landslides | Year: 2015

Dessie town is located in a tectonic depression along the western rift margin with a young, high energy relief. Study area is known for numerous landslides in the past. These landslides are of different types, from shallow soil creeping to huge deep-seated landslides with appreciable consequences. Landslides endanger the quickly growing regional centre of Dessie and its infrastructure. Four typical recent landslides have been selected and studied in detail using both remote sensing and field observations from 2013. The described reactivation and new landslide events have been caused by a combination of natural influences and anthropogenic activities. Since seasonal rainfall is the main external triggering factor, precipitation data from Dessie weather station were analysed. The degree of negative human impact on slope instability was also discussed. Endangered zones and the actual risk in the studied localities were identified, and adequate measures were proposed. © 2015, Springer-Verlag Berlin Heidelberg.

Varilova Z.,Museum of the Town of st Nad Labem | Zvelebil J.,GEO TOOLS | Hubatka F.,KOLEJ CONSULT and Servis | Benes V.,R.Ø.S.A. | Frolka J.,KOLEJ CONSULT and Servis
Acta Universitatis Carolinae, Geographica | Year: 2014

The study contains the results of non-destructive research of the Pravčická Brána Rock Arch which focuses on the structure and natural dynamics of this rock formation and its current level of stability. The main results include a description of the block fabric of the rock body and the nature of the contact zone between the arch beam and the southern pillar, discovery of relatively fresh secondary fissures and identification of zones with weakened strength within the sandstone massif. Also the local hydrodynamic regime was determined by a combination of geophysical methods. Long-term monitoring has demonstrated slow and irreversible body movements and reversible quasicyclical movements associated with changes in temperature on a scale of days up to years. The collected information was used to develop a structural deformation model of the arch body, including a description of the nature of the disintegration. The work was designed to fully respect the protective conditions of the site, to facilitate future follow-up activities and to monitor any possible negative changes in the rock massif.

Hadded R.,National Institute of Agronomy of Tunisia INAT | Nouiri I.,National Institute of Agronomy of Tunisia INAT | Alshihabi O.,The Arab Center for the Studies of Arid Zones and Dry Lands | Massmann J.,Federal Institute for Geosciences and Natural Resources | And 4 more authors.
Water Resources Management | Year: 2013

This paper describes the development of a Decision Support System (DSS) for groundwater management of the 'Zeuss Koutine' aquifer in southeastern Tunisia using the WEAP-MODFLOW framework. First, a monthly MODFLOW model was developed to simulate the behaviour of the studied aquifer. A conceptual model of the study area was designed and a WEAP schematic representing the real hydraulic system was developed. In addition to the studied aquifer, other water resources available in the region, such as desalination plants and groundwater, were taken into consideration in this DSS. Inputs to the hydrogeological model include natural recharge and inflow from higher neighbouring aquifers. Outputs are mainly agricultural, touristic and urban water consumption. It was shown that the DSS developed was able to evaluate water management scenarios up to 2030, especially future water consumption, transmission link flow and active cell heads of the MODFLOW model for each time step. Results for the Zeuss Koutine aquifer demonstrated that desalination plants already built in the cities of Jerba and Zarzis have contributed to decreasing the continuous drawdown observed before 1999. The use of a sea water desalination plant to supply Jerba and Zarzis in the future is a solution for reducing the Zeuss Koutine aquifer drawdown. Defining its optimal capacity over time poses a new research question. © 2013 Springer Science+Business Media Dordrecht.

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