Modelling and verification of the permafrost distribution in the Bernese Alps (Western Switzerland)

Results of a study to investigate the permafrost distribution and rock glaciers in the Bernese Alps (western Switzerland) are presented. Two different methods were applied. First, a computer model (PERM) has been developed, which allows one to calculate and map the probability of alpine permafrost occurrences by means of a digital terrain model on the basis of rules of thumb considering altitude, aspect, slope and type of ground cover. Second, an inventory of 80 rock glaciers has been established from the results of the interpretation of aerial photographs and field work. Active and inactive rock glaciers were used as indicators to verify the permafrost distribution calculated with PERM. Coincidence of rock glaciers with the simulated permafrost distribution proved to be very good, which seems to confirm the results of the permafrost modelling. However, the number of the rock glaciers — probably for climatic reasons — is too small to allow a strict statistical verification of the permafrost map produced with PERM. The interpretation of the field data suggests that the lower limit of discontinuous permafrost in the Bernese Alps probably reaches slightly further down than in the more continental central Alps.