Significant Topographic Changes in the United States
Relevance for Anthropogenic Geomorphology
The product of this study is a broad-based inventory of specific topographic surface changes resulting from 20th century human geomorphic activity in the United States. Most other studies in anthropogenic geomorphology have concentrated on description and analysis of site-specific geomorphic changes caused by human activities or on comparison of the total effects of humans as geomorphic agents compared to natural agents. The site-specific studies are useful for providing examples of the specific modifications of landforms that result from human activities, while the comparison studies are useful for placing the magnitude of human processes within the context of other ongoing natural geomorphic processes (usually expressed as annual rates of material moved). This study fits into the gap between the site-specific examples of actual anthropogenic changes and the general surveys of human geomorphic agency. The inventory produced in this study includes quantified land surface change features from human activity at specific locations but over a broad study area (the conterminous United States). As such, the distribution and patterns of human geomorphic features can be characterized for a large area. Given suitable future collections of multitemporal elevation data, the inventory sets the stage for ongoing topographic change monitoring in which rates of material moved per unit time can be calculated, as was done in the existing studies of the overall contribution of human geomorphic processes. This investigation contributes to the broad category of geographic studies that document the effects of human action upon the environment. The results from this project should be relevant for any research efforts that consider the general influence of physical geography on natural or cultural phenomena, such as habitat fragmentation, water quality, land use change, and resource extraction.