Remote Sensing and GIS in Digital Terrain Modeling

Abstract

Topography is an important land surface characteristic that affects most aspects of the water balance in a catchment, including the generation of surface and subsurface runoff, the flow paths followed by water as it moves down and through hillslopes, and the rate of water movement. Topographic attributes derived from digital elevation models (DEMs) and automated terrain analyses are increasingly used in terrain analysis and geomorphological research. DEM is convenient for representing the continuously varying topographic surface of the Earth, and it is a common data source for terrain analysis and other spatial applications. The utility of the DEM is evidenced by widespread availability of satellite-based DEMs at different resolutions and by the ever-increasing list of uses from DEM. Common terrain attributes, which could be computed from a DEM include slope gradient, slope aspect, slope curvature, upslope length, specific catchment area, compound topographic index (CTI) etc. One of the most limiting factors of the use of the DEM is its accuracy and spatial resolution. DEM of different resolutions could be used to derive DEM-based attributes, which could be used to investigate and evaluate resources like soil, water, vegetation, etc., in given landscape. In digital terrain modeling, predictive relationships developed at one scale might not be much useful for prediction of variables at different scales. That may limit the use of terrain variables developed for large scale in small-scale studies.