Rockglacier kinematics derived from small-scale aerial photography and digital airborne pushbroom imagery

摘要

The study presents a regional approach for the quantification of rockglacier kinematics combining analogue small-scale aerial photography and data of the High Resolution Stereo Camera - Airborne (HRSC-A), a digital linear array sensor. The potentials of the latter are the simultaneous recording of panchromatic and multispectral data, and the fast and automatic processing of the raw data as well as the high spatial resolution. In rockglacier studies, these data were used for the first time. For the study area (Turtmann valley, Swiss Alps) the sensor provided multispectral orthoimages with a resolution of 0.5 m (6350 m a. s. l. flight altitude) and a digital terrain model (DTM) with a 1 m grid spacing. The implementation of multi-temporal orthophotos in an image correlation software (CIAS) was successfully applied; surface velocity fields of 30 rockglaciers were measured and analysed over a period of 26 years (1975-2001). The results showed horizontal deformation rates in the range of several decimetres to metres per year. The comparison of multi-temporal DTMs enabled the quantification of vertical changes in rockglacier geometry. One rockglacier featured unusually high horizontal deformation rates of more than 3 m/a and at the rockglacier front an increase in thickness of approximately 20 in occurred between 1993 and 2001.