Hypsometric properties of mountain landscape of Hunza River Basin of the Karakoram Himalaya

Abstract

Within Karakoram Himalaya, Hunza River Basin (study area) is unique for a number of reasons: 1) potential impacts of highly concentrated high-pitched mountains and glacial ice; 2) the glaciated portions have higher mean altitude as compared to other glaciated landscapes in the Karakoram; 3) this basin occupies varieties of both clean and debris-covered glaciers and/or ice. Therefore, it is imperative to understand the stability of topographic surface and potential implications of fluctuating glacial-ice causing variations in the movement of material from higher to lower elevations. This paper advocates landscape-level hypsometric investigations of glaciated landscape lies between 2280–7850 m elevation above sea level and non-glaciated landscape between 1461–7570 m. An attempt is made to understand intermediate elevations, which disguise the characteristics of glaciated hypsometries that are highly correlated with the Equilibrium Line Altitude (ELA). However, due to data scarcity for high altitude regions especially above 5000 m elevation, literature values for climatic conditions are used to create a relationship between hypsometry and variations in climate and ELA. The largest glaciated area (29.22%) between 5047 to 5555 m lies in the vertical regime of direct snow-accumulation zone and in the horizontal regime of net-accumulation zone (low velocity, net freezing, and no-sliding). In both landscapes, the hypsometric curves are ‘slow beginning’ followed by ‘steep progress’ and finally reaching a ‘plateau’, reflecting the rapid altitudinal changes and the dominance of fluvial transport resulting in the denudation of land-dwelling and the transport of rock/debris from higher to lower altitudes. Reported slight differences in the average normalized bin altitudes against the cumulative normalized area between glaciated and non-glaciated landscapes are an indicator of slightly different land-forms and landform changes.