THE USE OF SATELLITE IMAGERY IN LANDSLIDE STUDIES IN HIGH MOUNTAIN AREAS

摘要

Landslides represent a serious threat to human life and activities in most high mountain chains.rnHowever, due to the difficult nature of such terrain, it is often difficult to assess directly the susceptibilityrnof slopes to landsliding. Hence, remote sensing offers many attractions for the examination of landslidernpotential in such environments, especially in less developed nations in which resources are stretchedrnand levels of environmental information are limited. However, there is a need to ensure that therntechniques are effective, reliable, and offer value for money in terms of the amount and accuracy of datarnthat can be extracted. Using a case-study, this paper compares the applicability of Landsat ETM+ andrnIKONOS imagery for the assessment of landslide susceptibility in natural terrain. This has beenrnundertaken on the basis of six study areas located in upland areas of Nepal and Bhutan. In each case,rnthe imagery has been used both to directly map landslides and to examine the occurrence of factors thatrnmight be important in landslide initiation, such as water seepage. The results from the imagery havernbeen bench-marked using field surveys. The study has demonstrated that at present Landsat ETM+rnremains the most cost-effective tool for mapping landslide susceptibility, due to its relatively low cost andrnhigh spectral resolution. However, its spatial resolution remains a significant limitation. This limitation isrnavoided by high resolution, multispectral IKONOS imagery, which finally allows even small landslides tornbe mapped in detail. However, the more limited spectral resolution is less useful for factor type mapping.rnUnfortunately, the high cost of this imagery will continue to preclude the development and use of thisrntechnique in developing countries.