This project aims to evaluate the vulnerability to Geohazards of a highly strategic facility in the Republic of Georgia, represented by the largest hydroelectrical facility of the Country: Enguri, and to assess the possible diverse geohazard scenarios that might occur, the preventive measures that can be realistically adopted by the main involved end-users, and the training activities that can be deployed to improve the capacity and know-how of young researchers and technicians of different countries. The Enguri plant furnishes 75% of the energy supply to Georgia and currently it is the World’s second highest arch dam with a height of 271.5 m. It is part of the Enguri hydroelectric power station (HES) that is partially located in Abkhazia, the separatist region of Georgia. Problems to Enguri would affect the energy distribution at all Georgia and moreover a possible overflooding from this reservoir would affect directly Abkhazia where the war just ended in 1992. The Enguri artificial reservoir is 15-km-long and at the foot of the dam there are located the settlements of Jvari and Potskho Etseri (8000 inhabitants in total, plus hundreds of sparse rural settlements). Several small landslides occurred at the slopes near the reservoir and on one side of the lake there is the huge landslide “Khoko”, fall of which in the reservoir would cause a big emergency (see the attached letter of the local Energy Company). On May 2014, the huge Dariali Valley landslide occurred close to another site selected for the construction of a new reservoir and killed 8 persons. Notwithstanding the very steep slopes surrounding the Enguri reservoir and the high seismicity of the region, no quantitative assessment of the slope stability has been performed for the region. The very high seismicity is due to the fact that the area is located at the foothill of the Greater Caucasus mountain belt, along a swarm of active faults running from Georgia to the Caspian Sea. Although it is commonly known that seismicity can increase slope instability and trigger landslides, no dynamic analyses of the stability of the slopes surrounding the reservoir have ever been performed. Moreover, an updated evaluation of the local maximum intensity of earthquake ground shaking by including the analysis of pre-instrumental earthquakes has not yet been performed. This data is of paramount importance to correctly quantify the Peak Ground Acceleration (PGA) induced by the largest earthquake that can be expected here in the future. Obtaining this seismic information, considering a sufficiently long historic seismic record, will enable us to perform a modern assessment of the security of the lifeline infrastructure of strategic importance to Georgia.
The main objectives of the project are the following:
1) Reconstruction of the pre-historic seismic activity of the main Quaternary faults nearby the Enguri hydroelectrical facility, and calculation of the maximum paleoseismic magnitude;
2) Calculation of the expected PGA in the area by integration of data on modern seismicity with paleoseismicity and local seismic coefficients;
3) Expand and complete the presently limited instrumental earthquake catalogues of Georgia by including the new paleoseismicity data;
4) Carrying out the assessment of static and dynamic slope stability with modern methods all around the artificial water reservoir;
5) Evaluation of the possible scenarios of tsunami propagation following the failure of the studied unstable slopes into the artificial lake, and of possible overtopping of the dam;
6) Evaluation of the possible scenario of flooding consequences to overtopping and inundation of material across the Abkhazia region and into the Black Sea;
7) Training activities comprising field exercises and instrumental knowledge, as well as indoor lessons (at partner universities and at NATO country universities) on both paleoseismic studies and landslide analyses, for preparing young researchers and technicians to carry out independent work and acquire the necessary skills for seismic hazard evaluation, slope stability and flood inundation analyses;
8) Involve end-members and furnish them with a GIS-based platform for the immediate use of the information obtained in the present project.
The expected outcomes include detailed maps and reports of all the data necessary to quantify the seismic and landslide hazards, together with a report describing the various possible scenarios. Particular emphasis will be given to propose measures to forecast these scenarios, such as a realistic scheme of monitoring of the more unstable slopes. Data and results will be disseminated via scientific papers and presentation to congresses, and will be also presented to the relevant end-users in a ready-suitable forms (GIS maps).
These investigations fully match the NATO Key Priorities: b-ii) Energy infrastructure security, and e-ii) Disaster forecast and prevention of natural catastrophes, and are particularly relevant because the studied hydroelectrical scheme is a fundamental infrastructure that produces energy to whole Georgia; especially in the case of possible landslide failure, the hydroelectrical plant would temporarily be unavailable with consequent problems to the whole country in terms of energy supply, and cessation of productive activities, etc; moreover, the falling of rocks debris into the artificial lake would produce partial infilling and long-term decrease in the capacity of the dam. The collaboration with Azerbaijan and Kazakhstan scientists would also have a positive feedback on international stability by increasing the cooperation with the conterminous Georgia and with NATO countries. Moreover, since the Caucasus foothills in Georgia and Azerbaijan share the same tectonically active structures, an improvement in the knowledge of the seismogenetic faults along these zones benefit both countries directly for seismic hazard and risk assessment.