A lot of effort goes into keeping maps and GIS data up-to-date. Things like country borders may change fairly frequently, but it might not seem like things like physical, topographical features would really require that much updating, right? Short of advancements in creating more accurate maps, it’s pretty reasonable to assume that the physical environment being mapped would remain pretty constant. Unfortunately, that isn’t always the case.
Human actions can have a profound impact on the environment and topography of an area. Things like strip mining and open pit mining are pretty obvious when it comes to things that alter the face of the landscape, but others are more insidious- human actions can seriously influence the hydrological cycle, erosion, and more. Water is a major force of change in the environment. It allows forests to flourish, carves waterways, and wears away mountains. This means that any human activity that uses water or alters its course will inevitably end up having some kind of impact on the physical environment.
Strip mining (also called “surface mining”) and open pit mining remove large sections of land from an area. Old, retired open pit mines can fill with water, creating artificial lakes. Strip mining can remove the tops from mountains, altering their elevation and the way that precipitation runoff sculpts the remainder of the landscape. As a result, topographical information on maps has to be updated to reflect these alterations. Even in situations where land reclamation programs are implemented to limit the often devastating topographical effects of strip mining, the area surrounding the mine is usually never the same afterward.
Mining isn’t the only human activity that alters the topography of the land. Anything that changes how water flows over the land will affect the physical environment. Thing includes things like logging and land clearing- the roots of trees and brush help hold soil in place, protecting porous rock and preventing the soil from being washed away. Over time, the removal of local plant life can drastically alter the land’s topography- erosion carves new valleys and widens river banks and streams, while logging itself can remove entire forests if sustainable forestry isn’t practiced.
Even something as simple as using water can change the physical environment in a big way. Using it for hydroelectricity requires waterways to be dammed, which alters their paths and changes the local landscape. Water accumulates upstream from the dam, forming artificial lakes and ponds, while flow is reduced downstream, making it necessary to figure out how to get more water to downstream areas without removing the dam. Irrigation and sanitation move water from one place to another, and end up taking it from its natural source without replenishing it. As a result, local water sources end up depleted, while previously dry areas can end up waterlogged, or even eroded completely. Currently, several areas of the U.S. are experiencing a water shortage caused by changes in the amount of water available to their area- when natural water sources are used up by agriculture and industry faster than they can be replaced with rainfall, serious droughts occur.
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Sometimes, human activities don’t just cause the land to change, they can also keep it from changing the way nature intended. Storms routinely batter beaches, causing inches of land to be lost every year from certain areas. When these areas happen to be popular attractions, beachfront residential zones, or adjacent to other waterways that are easily clogged by deposited sand, then erosion control measures are usually implemented. These measures include deepening jetties and inlet channels, replacing lost sand, and planting dune-friendly grasses around beaches to help hold sand in place. These can help keep beaches from shrinking, but have to be kept up perpetually in the face of natural erosion. Measures like replacing lost sand can help keep beaches from being lost, but often end up changing the areas from which the replacement sand is taken.
New innovations in sustainability help limit the impact of human actions on the physical environment, but these often come with a cost. Sand can be pumped in, water can be piped in, and forests can be replanted, but these measures usually require the use of a lot of energy, which is generally provided by oil, coal, gas, and other resources whose acquisition changes the face of the environment, too. As a result, preserving the topography of an area that’s been subjected to surface mining, irrigation, deforestation, and other activities generally means allowing a different area to change, instead.
References:
Humans and the Water Cycle: http://www.sciencelearn.org.nz/Contexts/H2O-On-the-Go/Science-Ideas-and-Concepts/Humans-and-the-water-cycle
Beach Erosion Control: http://www.dep.state.fl.us/beaches/programs/bcherosn.htm
Surface Mining: http://en.wikipedia.org/wiki/Surface_mining
Effects of Logging and Logging Roads on Sediment Deposition from Steep Terrain: http://www.ingentaconnect.com/content/saf/jof/1972/00000070/00000003/art00007
