Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in the development of guidelines for sustainable land use planning. The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship.The factors that have been used for landslide hazard analysis can usually be grouped intogeomorphology, geology, land use/land cover, and hydrogeology. Since many factors are considered for landslide hazard mapping, GIS is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Remote sensing techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope, lithology, and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how the landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery.
Using satellite imagery in combination with GIS
and on-the-ground studies, it is possible to generate maps of likely
occurrences of future landslides. Such
maps should show the locations of previous events as well as clearly indicate
the probable locations of future events. In general, to predict landslides, one
must assume that their occurrence is determined by certain geologic factors,
and that future landslides will occur under the same conditions as past events. Therefore,
it is necessary to establish a relationship between the geomorphologic conditions
in which the past events took place and the expected future conditions.
Natural disasters are a dramatic example of people
living in conflict with the environment. Early predictions and warnings are
essential for the reduction of property damage and loss of life. Because
landslides occur frequently and can represent some of the most destructive
forces on earth, it is imperative to have a good understanding as to what
causes them and how people can either help prevent them from occurring or
simply avoid them when they do occur. Sustainable land management and
development is an essential key to reducing the negative impacts felt by
landslides.
GIS offers a superior method for landslide
analysis because it allows one to capture, store, manipulate, analyze, and
display large amounts of data quickly and effectively. Because so many
variables are involved, it is important to be able to overlay the many layers
of data to develop a full and accurate portrayal of what is taking place on the
Earth's surface. Researchers need to know which variables are the most
important factors that trigger landslides in any given location. Using GIS,
extremely detailed maps can be generated to show past events and likely future
events which have the potential to save lives, property, and money.
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