Quantification of the Effects of Topographic Changes
Quantification of the Effects of Topographic Changes
The terrain parameters measured for each feature in the topographic change inventory are useful for describing the surface modifications at the specific locations of the polygons. However, in many cases the individual change polygons are members of a larger set that collectively represent a surface disturbance distributed over an area greater than that of any of the individual polygons. These groups of change polygons produce cumulative effects on the environment, and quantification of the effects of the changes must consider the numerous polygons together. The effects of changes over areas more broad than the scale of individual polygons are quantified below.
Filter Total Items: 7
Proximity of Topographic Change Areas to Other Features
The near-national extent of the topographic change dataset also allows for spatial comparisons, such as proximity of change polygons to roads and urban areas. Such comparisons have been done for the proximity of mines to roads and major cities for the five focus ecoregions. This figure shows the locations of the centroids of mining polygons within the five ecoregions and the locations of cities...
Regional Differences in the Effects of Surface Mining
Because the topographic change inventory has near-national coverage, comparisons can be made among broad regions. This figure shows a set of five Level III ecoregions that were used as a basis for regional comparisons of topographic change.
Visual Impacts
When contrasting the general nature of anthropogenic processes versus other geomorphic agents, the visual impact of human activity generally is greater than that of natural processes.
Hydrologic Effects
Because the shape of the land exerts strong control over the collection and flow of surface water, changes to the topography can have a significant effect on local drainage conditions. The figure below demonstrates how the local surface drainage features have been altered as a result of surface mining operations.
Comparison with Land Cover Status and Trends Data
The topographic changes detected in this study usually have a corresponding land cover change. To examine this relationship more closely, features in the topographic change inventory were compared with data from an ongoing study of the status and trends of land cover in the United States. The status and trends project uses a sampling-based approach in which land cover maps and change products are...
Error Sources, Uncertainty, Limitations, and Uses
In a study such as this one, with diverse input datasets that cover a broad area, data characteristics and quality can have spatially varying effects on derived information. In the context of data processing methods, unique characteristics of both the NED and SRTM data had to be accounted for in the processing approach to reduce errors of commission. While it is desirable to have a final...
Results Information
The primary result of the data processing explained in the Methods section is a polygon feature dataset that locates and describes the areas in the conterminous United States that have experienced significant topographic change during the 20th century.