Along Georgia’s border with Russia, about two hours north of the Georgian capital of Tbilisi, the Tergi River flows on an almost 400 mile journey down from the Devdorak Glacier atop Mount Kazbek to the Caspian Sea. The river has been a valued source of water for the communities along its banks for thousands of years, and the gorge which it cuts through the Caucasus has been a key trade route as well.
It has recently become the site of a controversial hydroelectric project. After not one, but two major landslides, the Dariali Hydropower Plant, located on the river, has become a topic of recent debate. The May 2014 landslide left three power plant workers dead and five others missing, it also completely impeded the Dariali Gorge, cutting of the region’s arterial roadway between Georgia and Russia, in addition to severing an essential natural gas pipeline providing Armenia with natural gas from Russia. The August landslide, reportedly larger than the one a few months before, resulted in the death of two more hydroelectric plant workers and necessitated a visit to the area by the Georgian president.
These events are not new for the region, which has been blighted by landslides for as long as local history remembers. This history makes local residents concerned. Other hydroelectric projects have succumbed to such hazards. For this reason and others ,the Dariali project, which would provide an estimated 108 Megawatts of electricity to the region, has already run into political controversy. The public does not fully accept the project, Eighty to 90 percent of the Tergi River would have to be diverted, leaving almost five miles of the riverbed completely dry, and threatening the local trout population. The project necessitated the rezoning of the area, removing its status as a national park under legal protection. Local people were concerned that construction began before a permit was issued, or before even mandatory public hearings were held.
Another issue is contribution of global warming to the latest two landslides. Devdorak Glacier, like other glaciers in the Caucasus, has been retreating in recent years. The meltwater could lead to increased water flow and thus contribute to natural erosion, increasing the risk of floods and landslides. Such dangers are well-established in the valley, as demonstrated by accounts as far back as 1869. Douglas W. Freshfield gives this account in his “Travels in the Central Caucasus and Bashan“:
“M.E. Favre, of Geneva, a well-known geologist who visited the Devdorak Glacier a few weeks after ourselves, came to the following conclusion as to the nature of the catastrophe. No avalanche, he says, could without the aid of water traverse the space between the end of the glacier and the Terek (Tergi river), and he accounts for the disasters which have taken place in the following way. He believes the Devdorak Glacier, to which he finds a parallel in the Vernagtferner Glacier in the Ötzthal Alps, to be subject to periods of sudden advance. During these the ice finds no sufficient space to spread itself out in the narrow gorge into which it is driven, and is consequently forced by the pressure from behind into so compact a mass that the ordinary water-channels are stopped, and the whole drainage of the glacier is pent-up beneath its surface. Sooner or later the accumulated waters burst open their prison, carrying away with them the lower portion of the glacier. A mingled flood of snow and ice, increased by earth and rocks torn from the hillsides in its passage, sweeps down the glen of Devdorak. Issuing into the main valley it spreads from side to side, and dams the Terek. A lake is formed, and increases in size until it breaks through its barrier, and inundates the Dariali Gorge and the lower valley.” [ed: place names have been modernized from original text]
Only time will tell whether or not the Dariali Hydropower Plant will be realized, and if so, what the effects will be for the region. Looking back at recent history, however, the safety of the project itself and the valley below seems suspect at the least.
For more information about the Dariali Gorge landslide see:
For a related GlacierHub story see: http://glacierhub.org/2014/09/03/flooded-with-memories-in-nepal