Sensitivity of landscape evolution and geomorphic processes to direct and indirect human influence

Abstract

An assessment of some consequences of human activities on geomorphic processes during the last century is presented. The effects of urban infrastructure development and mining on direct and indirect denudation and geologic materials transport in several study areas are analysed. The temporal occurrence of landslides is analysed in another study area. Results obtained are compared with data on denudation and sediment transport from the literature, as well as with data on geomorphic disaster trends for the same period. Data obtained indicate that people are nowadays the main geomorphic agent. «Technological denudation» appears to be one or more orders of magnitude greater than natural denudation or sediment transport rates. The «human geomorphic footprint» or rate of anthropogenic landform construction could reach a total area of continental proportions by the end of the century. The frequency of geomorphic hazard events, at local, national and global levels, has increased about one order of magnitude in half a century and shows exponential growth trends, which appear to be correlated with GDP (gross domestic product). It is proposed that growing population, wealth and technology (for which GDP can be used as an indicator) is the driving force behind a widespread «global geomorphic change» that affects landscape sensitivity. The effect of geomorphic change is added to that of climate change and implies an acceleration of landscape evolution rates as well as an intensification of geomorphic hazards. It is suggested that measures to mitigate geomorphic change should be taken in order to curb the observed trend towards increasing geomorphic disaster occurrence.