Technogenic salt karst

Introduction. There are the speleological and engineering-geological areas in karst studies. Engineeringgeological area has two aspects, the surface aspect including the construction of surface buildings in the areas with the karst hazard and the subsurface aspect of prevention and protection from karstification when developing mineral deposits. Although shafts in salt mines has been working since the Middle Ages, the salt karst is still the reason for the destruction of a lot of salt mines. Research aim is to reveal the physical and chemical mechanism of salt karst development and the reasons for accidents and flooding in salt mines. Methodology included the analysis of regular survey measurements of surface deformation, recording of brine manifestations in mine workings, chemical analyses in brines, hydraulic measurements at surface watercourses, direct determinations of brine aggression, geophysical research by the natural field method, vertical electrical sounding, etc. In recent years, in order to control surface deformation, the data from the radar survey have been used. Results. A clue to the mechanism of salt karst responsible for accidents is the theory of hydrodynamic systems by A. M. Ovchinnikov, the elements of which are the areas of accumulation, transit, and discharge. Brine motion is in the supra-salt reservoir. The trajectory of brine motion is determined by the relief of the salt table. Pressure flow take up the elevated terrain. Accumulation areas are confined to stream corridors permeating the low-permeability strata which covers the salt. The area of transit distinguishes between the zone of the pressure flow and the vertical slot where the brines move in the gravity turbulent conditions. Mine workings make up the discharge area. Within them under the action of aggressive brines triangular niches develop. Pillars undercut results in their collapse and surface sink. Summary. Salt karst development mechanism disclosure has made it possible to propose the methods for predicting its effect and the ways of predicting flooding in salt mines.

Exposure of tourism development to salt karst hazards along the Jordanian Dead Sea shore

The Dead Sea shore is a unique, young and dynamic salt karst system. Development of the area began in the 1960s, when the main water resources that used to feed the Dead Sea were diverted towards deserts, cities and industries. During the last decade, the water level has fallen by more than 1 m per year, causing a hydrostatic disequilibrium between the underground fresh waters and the base level. Thousands of underground cavities have developed as well as hectometre-sized landslides. Despite these unfavourable environmental conditions, large tourism development projects have flourished along the northern coast of the Jordanian Dead Sea. In this work, which is based on a multi-method approach (analyses of radar and optical satellite data, in situ observations, and public science), we show that a 10 km long strip of coast that encompass several resorts is exposed to subsidence, sinkholes, landslides and flash floods. Geological discontinuities are the weakest points where the system can re-balance and where most of the energy is dissipated through erosional processes. Groundwater is moving rapidly along fractures to reach the dropping base level. The salt that fills the sediments matrix is dissolved along the water flow paths favouring the development of enlarged conduits, cavities and then the proliferation of sinkholes. The front beaches of the hotels, the roads and the bridges are the most affected infrastructure. We point out the importance for the land planners to include in the Dead Sea development schemes the historical records and present knowledge of geological hazards in the area.

Karst as Important Resource for Geopark-Based Tourism: Current State and Biases

The United Nations Educational, Scientific and Cultural Organization (UNESCO) Global Geoparks initiative balances the conservation of geological heritage with its use in purposes of tourism industry. However, the resources of geoparks and the current state of their use are yet to be fully understood. The phenomenon of karst (caves, sinkholes, etc.) appears to be a valuable geopark resource because it attracts numerous visitors interested in geo-, eco-, and speleotourism. Of 140 global geoparks, 37% exploit karst resources. These are located chiefly in Europe and Southeast Asia. Just a few geoparks are fully based on karst features and the others use this resource together with other geological heritage resources. Global geoparks tend to emphasize either particular karst elements or entire karst landscapes. Many interesting features (e.g., gypsum and salt karst) are underrepresented in global geoparks. The UNESCO Global Geoparks initiative should become more phenomenon-focused to offer full representation of karst resources. For some countries like Russia and the United States, where geoparks have not been created yet, the consideration of karst resources may provide significant advantages in the strategic development of geopark-based geotourism.