Remote sensing and geomorphometric assessment of topographic complexity and erosion dynamics in the Nanga Parbat massif

The dynamic mountains of the western Himalaya are the result of complex interactions involving tectonic, structural, lithological, climatic and surface processes. The multi-scale dynamics of surface processes in this region are largely unknown. This paper assesses the spatial complexities of the topography at Nanga Parbat, as we seek to understand erosion dynamics, differential denudation and the geodynamics of uplift and denudation, Spatial analysis of a high resolution digital elevation model and three-dimensional terrain simulations using satellite imagery indicate that the topographic complexity of Nanga Parbat is highly scale-dependent and exhibits a hierarchical order that is reflective of erosion dynamics. Observations and analyses reinforce prior understandings of rapid rates of uplift and high rates of surficial denudation. Results indicate that climate controls the topographic complexity of the massif, although a tectonic influence is present and is largely masked by the overprinting of surface processes with time. Consequently, Nanga Parbat is seen to owe its origin to crosionally induced tectonic uplift and rapid surficial denudation. Rapid uplift altered erosion dynamics and further accelerated erosion resulting in extreme relief. Nonetheless, the differential denudation resulting from erosion dynamics does not appear to be in spatial balance with the regional scale tectonic mass flux. Systematic integration of dynamic models that account for the scale-dependencies of subsurface and surface processes are required to study the nature of this complex system and explain topographic evolution.