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Processes of Formation and Evolution of Karst

#3225


Numerical Model Development for Phenomena Going Along with Karst Formation and Evolution Processes

Tech Area / Field

  • ENV-WPC/Water Pollution and Control/Environment

Status
8 Project completed

Registration date
28.03.2005

Completion date
08.12.2008

Senior Project Manager
Kulikov G G

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • Kazan State University / Scientific Research Institute of Mathematics and Mechanics, Russia, Tatarstan, Kazan

Collaborators

  • Lawrence Berkeley National Laboratory / Earth Sciences Division, USA, CA, Berkeley\nCentro di Ricerca, Sviluppo e Studi Superiori in Sardegna, Italy, Sardinia, Pula

Project summary

Karst is a set of processes and phenomena stipulated by rock dissolving by subsurface waters that may result in changes of the rock structure and conditions, possible formation of cavities and resultant ground surface deformations. The following karst types can be distinguished basing on the dissolved rock type: carbon-bearing (in limestone, dolomites, fragmental rocks with carbon-bearing cement), sulfate-bearing (in gypsum, anhydrites) and salt karst (in rock salt and potassic salt). Phenomena going with the last type karst are of the specific nature (superficial character of dissolving salt rock mass, availability of an area of protecting saturated brines, etc.) and they will not be taken into consideration under the project.

Karstic cavities and voids, as well as intensive motion of subsurface waters in karsting rocks may result in particles going out of terrigenous rocks above the karsting mass (the so called “suffosion”) along with water fluxes, that’s why the term “karst-and-suffosion processes” is sometimes used.

A number of requirements have to be satisfied to induce karst evolution processes, namely:

  1. Availability of an ancient karst area contemporized to well-penetrable aquifers and being a drain for surface water sources;
  2. Availability of a rather intensive water flux;
  3. Discharge of incoming water in the karsting mass;
  4. An ability of solution to dissolve;
  5. Availability of a set of cracks which a water flux is going through

The project proposes studies in two areas, such as karsting and suffosion.

Karsting is the process occasional to the mass of soluble (karsting) rocks (the dissolving process proper). Dynamics of the process essentially depends on the ability of subsurface waters to dissolve rocks, velocity and direction of a subsurface water flux, as well as the structure of cracks and the nature of convection-diffusion transport processes in them.

Suffosion means the subsurface flow erosion process. Formation of cavities in rocks in the form of long and relatively thin channels oriented approximately along a water flow is one of the possible features of the process. Such a phenomenon is called “piping” and it was observed, in particular, during some studies of possible causes of water-development project accidents. One can suppose probability of similar phenomena under different conditions.

Actual suffosion processes can go along with many other phenomena that complicate the general picture (caving of a channel roof, specific features of fractured ground moving with the water flow along the channel, etc.). However, it’s reasonable to study the mechanism, features and properties of the phenomenon separately from the others. Note that these features themselves may be complex enough, instabilities of growth, branching of channels, etc. are possible (the general picture of forming channels in theoretical models will, possibly, remind fractal structures).

The main project goal is to develop the required theoretical apparatus and computational tools to simulate and study principal mechanisms of karst evolution and rock suffosion using computer simulation methods.

New physical and mathematical models of flow and dissolution processes, for studying the influences of impurities on dissolving properties and the influences of dissolving processes on the flow properties and suffosion in ground will be developed under the project.

Efficient numerical methods and algorithms will be proposed for models under development.

The project results could be used as a foundation for further development of improved environmental prediction means. Namely, the project could be further developed

  • to solve problems of estimating karst riscs during water-development works;
  • to solve problems caused by changes of mechanical properties of rock and soils in regions with karstic and suffosion processes (rheomechanics).


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