Glacier mapping from multi-temporal optical remote sensing data within the Brahmaputra river basin

Glacier distribution and glacier changes were investigated in the Upper Brahmaputra River Basin using remote sensing and GIS in order to determine the influence of melting glaciers on the long-term runoff of the Brahmaputra River (EU-project BRAHMATINN). Current glacier distribution and glacier changes since the 1970/80s were mapped using multi-temporal optical remote sensing data from the Landsat series and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Repeat glacier outlines were then combined with the digital elevation model from the Shuttle Radar Topography Mission (SRTM) and analyzed within a GIS in order to assess spatio-temporal gradients in change in glacier area. Our findings yield total glacier area losses between -7 to -13% per decade in the Upper Brahmaputra River basin (UBRB) for the period from 1970/80 to 2000; c. 175 km w.e. glacier mass was lost, which equals c. 7 km w.e. glacier mass loss per year. This corresponds to a yearly average mass balance of more than -0.3 m w.e.