13 September, 2018 – Final conference of NATO SfP G4934 project ” Security against geohazards at the major Enguri hydroelectric scheme, Georgia”- I. Javakhishcili Tbilisi State University, Georgia

Security against geohazards at the major Enguri hydroelectric scheme, Georgia (2015-2018)

The project focuses to evaluate the vulnerability to Geohazards of the largest hydroelectrical facility of Georgia: the Enguri dam and reservoir, 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 dam is part of the Enguri hydroelectric power station (HES) that is partially located in Abkhazia, occupied territory of Georgia. Problems to Enguri would affect the energy distribution at all Georgia, and Abkhazia depends 100% on its energy supply.

Our project assessed the stability of the steep mountain slopes surrounding the Enguri water reservoir, with special emphasis to the active huge “Khoko” landslide . After studying the local geological, geomorphological and geotechnical characteristics of the landslide slope, and the paleoseismology and seismology of the region, we were able to model a possible unstable volume of up to 48 ± 12*10e6 m3. The unstable mass is presently moving by creep at an average velocity of 4-5 cm/yr. Based on all surveyed field and instrumental data of the region and numerical modelling, we concluded that the unstable mass can fall into the reservoir in the case of a Peak Ground Acceleration of 0.46, compatible with an earthquake of Mw > 6.9 at 18 km of distance. The society that manages the hydroelectrical facility and all the end-users, comprising Ministries and Civil Protection, have been involved during the whole study and informed on the outcomes.Training activities of young researchers, technicians and students from NATO partner countries and NATO countries were carried out successfully. A continuous system of monitoring of the landslide head scarp hasbeen installed by us in cooperation with local authorities. Data are continuously monitored and evaluated, and represent one of the main legacies of this project. Finally, a wide popularisation activity was carried out, which culminated in a series of news on printed and digital journals and TV.

Current status
All the planned activities have been successfully carried out and the main objectives reached:
1) we studied the reservoir slopes in order to find active landslides, recognizing Khoko as the main one,
2) we re-evaluated the whole seismicity of this part of the Caucasus for both historical and instrumental earthquakes,
3) we discovered new active faults in the region based on field and geophysical data,
4) we recalculated the seismic Peak Ground Acceleration at the Enguri site;
5) we quantified the slope instability of the main active Khoko landslide (site in Fig. 1) under different levels of the Enguri lake and different water saturation of the slope;
6) we assessed the slope instability of Khoko landslide under the effects of earthquakes in pseudo-static conditions and by full dynamic seismic shaking solicitation of the slope;
7) we carried out the tsunami modelling caused by a possible failure of the slope into the water reservoir;
8) young researchers especially from Georgia, Kazakhstan and Azerbaijan, as well as from USA
and Italy, have been trained on the topics of the project;
9) due to the active slope deformations that we recognized along the Khoko landslide, which faces the water reservoir, we anticipated proactive measures by planning and installing continuous automatic monitoring instruments that are measuring with extreme precision the active movements of the landslide, and we installed also a series of bench marks that have been measured by GPS each six months. These instruments, the related training of local technicians, and the general know-how will constitute an important legacy after the ending of our NATO project;
10) we involved all the main end-users, especially the Enguresi Dam Society, the Ministry of Energy and Environment, and the Ministry of Infrastructures;
11) we developed the project web-site, published several scientific articles on main international journals, gave presentations at international congresses, and published a main outreach papers on the international journal EPISODES, which is the official journal of the International Union of Geological Sciences.

Participants:

A total of 31 people has been directly involved during the three years of this project. Among these, 23 are scientists, plus four PhD student, 2 Msc students, and 5 Bsc students.
Among the scientists, 11 are senior researchers or professors, 10 of which are stipendiary and one is a professional consultant. The remaining 12 scientists are represented by young researchers. This shows a good balance between senior and young representatives.
Out of the total involved people, 19 are men and 12 are women
http://www.enguriproject.unimib.it

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