A critical assessment of the sensitivity concept in geomorphology

The landscape sensitivity concept concerns the likelihood that a given change in the controls of a system or the forces applied to the system will produce a sensible, recognisable, and persistent response. The idea is an essential element of the fundamental proposition of landscape stability. This is described as a function of the spatial and temporal distributions of the resisting and disturbing forces and is known as the factor of safety or the stability index. The resistance of a system is defined by the system specifications: its structure, strength properties, transmission linkages, coupling efficiency, shock absorption capacity, complexity and resilience. The disturbing forces include the steady application of energy from the specified tectonic, climatic, biotic, marine and human environmental controls. Change takes place through time and space as a normal process–response function to these specifications and involves material transport, morphological evolution and structural rearrangement. These, in turn, progressively change the system specifications, which alters the performance through time. To make progress with these issues, the nature of waves of aggression, temporal adjustments to disturbing forces, spatial interactions with structure, divergent pathways of change propagation, evolution of ‘barriers to change,’ effects of inheritance, decoupling, and the effects of change on system specifications all need to be understood at all temporal and spatial scales.