Landscape Reading for Alpine Rivers: A Case Study from the river Biya

Abstract

Anthropogenic stressors have altered the hydromorphological characteristics of rivers worldwide. Environmental guiding principles are essential for planning sustainable river restoration measures. The alpine river Biya, located in the Russian Altai mountains, originates from Lake Teletskoye and joins the Katun near Biysk, forming the Ob. The Biya represents a hydromorphological reference system in anthropogenically ‘least-disturbed’ condition. The presented study aimed to assess the river’s undisturbed morphology in relationship with the geological history of three different river stretches based on an adapted landscape reading approach using remote sensing information (ASTER GDEM v3). The established widths of the active channel, active floodplain and morphological floodplain as well as the longitudinal section were used to explain the differences between upper, middle, and lower Biya. The results confirm differences in the geological origins between the upper Biya, which has previously been described as the least developed and narrowest, and the other two stretches based on the analyses of morphological parameters. Morphological floodplain width could best explain the differences between upper (0-86 km), middle (86-196 km), and lower Biya (196-301 km). The study further showed a clear relationship between the variations in river patterns and adjacent topographic structures (valley confinements, tributary interactions), highlighting that any assessment of river morphology must consider the wider surroundings of a river stretch. The presented morphological observations and analyses of the Biya show that easily obtainable parameters can detect differences in the morphological history of river stretches within the same catchment, supporting process understanding.