The Influence of Climate Changes on Mudflow Formation in Permafrost Areas: a Case Study for Chukotka Peninsula

The factors influencing the formation of mudflows in areas of the permafrost are considered. The data of studies performed in two regions of Chukotka – “Continental” (the Anyuysky ridge) and “Coastal” (the Iskaten ridge) were used for this research. The air temperature data series obtained in Chukotka in 2000–2020 demonstrate a steady growth of the average annual values. The air temperature rise estimated for the mudflow–dangerous period (June–August) amounted 1.4°C for the “Continental” area, and 1.0°C for the “Coastal”. This warming affects thickness of the seasonal melt layer of permafrost, mainly in the bottoms of valleys and on the slopes of mountains. This factor promotes the involvement of certain volumes of ground into mudflows. As a result of the research, it was found that the dynamics of the change in the thickness of the seasonal melt layer within the studied areas is positive, which is a consequence of warming and leads to additional moistening of grounds. The two periods of the mudflow formation were identified. During the first one (May–June), the mudflow formation is connected with the onset of intensive snowmelt that is favorable mainly for snow-water streams and loose mudflows. In the second period (July–August), mudflows are mostly caused by liquid precipitations, when the maximum thickness of seasonal melt layer is reached. It is the second period when a release of a large cohesive mud stream is the most probable. On the whole, the results obtained allow making a conclusion that in the near future the predominant type of mudflows in Chukotka will remain those of snow genesis. But, at the same time, under conditions of the climate change, occurrence of the snow-water mud streams will increase, especially in the “Coastal” area.