4 October 2022
The Beshbadam landslide in Kyrgyzstan
Loyal reader Isakbek Torgoev has very kindly written to highlight the fascinating Beshbadam landslide in Kyrgyzstan. I had not been aware of this one – it is remarkable.
The slide was triggered by exceptional rainfall across Central Asia. Isakbek kindly provided a commentary about the event that I have used here.
The spring of 1969 was record-breaking in terms of the number of newly formed and activated old landslides in the Central Asian region. Over a vast area that includes mountain slopes, foothills and the valley part of the Fergana Valley, almost 2,000 landslides occurred in Kyrgyzstan and Uzbekistan alone, mainly in loess deposits that cover the slopes bordering the valley.
The main reason for the massive catastrophic activation of landslides, in the period from 10 to 13 March 1969, was the combination of intense melting of the anomalously thick snow cover with the peak of spring rains. The amount of atmospheric precipitation from November 1968 to May 1969 was more than double the long-term average. The winter of 1968-69 was also characterised by record snow accumulation, which exceeded the norm by 1.5 to 3.0 times, such that the height of snow cover in the foothills of the Fergana Valley at the end of February exceeded 140 cm.
This combination of an abnormally cold and wet winter with an abnormally wet spring has caused a huge number of new landslides throughout Central Asia. In fact, in the entire history of hydrometeorological observations, starting from 1913, such a combination of anomalous precipitation and temperature, both in the cold and in the spring period of 1969, has not been repeated.
The Beshbadam landslide is located at 41.145, 72.916. It is an absolute beauty. This is a Google Earth perspective of the landslide:-
This is a very large, complex landslide. There are two main components, on the left side of the image is a large failure covering two sub-catchments. I have marked the head of this landslide as Crown 1. Isakbek has informed me that this landslide in 1.5 km long and 650 m wide at the head. To the right is another, much longer failure extending to the ridge, which I have marked as Crown 2. This component is 4.4 km long. The total volume of the landslide is about 5 million cubic metres, with a depth of 40 metres.
Isakbek has very kindly provided a historic photograph of the landslide:-
This is (I think) the Crown 2 component of the Beshbadam landslide, which has developed substantially since.
The landslide reminds me a little of the remarkable Slumgullion landslide in Colorado, USA. It would be interesting to know if the Beshbadam landslide shows similar movement patterns.
The Google Earth image shows other landslides in this area, and as Isakbek noted there are many other substantial landslides in the region. These have probably not received the attention they deserve from the wider landslide community, although the Asian Development Bank is currently funding a programme focusing on landslide risk management in Kyrgyzstan.