Influence of urbanization on permafrost: a case study from Mohe County, northernmost China

Abstract. Mohe County, northernmost China, is one of the densely populated areas in permafrost regions. The urban population has grown from about 25 000 residents in 1992 to more than 41 000 in 2011. Resident's life is closely related to permafrost environment. This paper adopted drilling, ground penetration radar, and ground temperature monitoring to investigate the permafrost in the urban area of Mohe County. The results show that the permafrost table is much lower in the urban area of Mohe County because of the urban heat island, surface disturbance of construction, space heating in winter etc. The permafrost table is 2.63–3.70 m on the edge of the urban area; the mean annual ground temperature is −1.0 to −1.33 °C. In the urban area, the maximum depth of permafrost has exceeded 15 m. The permafrost in the undisturbed area is 1.65–2.0 m, with much lower ground temperature −2.75 °C. Evidences outline a clear distribution rule that, from the edge to the center of the urban area of Mohe County, the permafrost table goes deeper and deeper, which states that the urbanization has significant influence on permafrost degradation. The degradation of permafrost in the urban area in turn has been affecting the residents' lives, such as water supply and stability of buildings.