Abstract
In this perspective paper we intended to review application of DEM and the other grid maps of landform classification, geology, pedology, vegetation, climate and hydrology to remote-sensing and numerical simulation of potential environmental change under CO2 climate.
Combination of digital maps and satellite images is of wide application. For instance we can analyse topographic situations and climatic conditions from the DEM for all pixels in the image. Air-temperature of each pixel can be estimated by using elevations and lapse rates calculated from observed values at altitude-known stations. The cumulative value of daily air-temperature is known to be essential for vertical arrangement of mountain vegetation belt recognized in the image. The daily temperature serves also for the forecast of snow-melt runnoff from snow-covered pixels in the image.
Distribution of agricultural landuse (dry and paddy field) and natural vegetation zoning (laurel, deciduous broad-leaved and coniferous forests, and alpine non-forest zone) in Japan is controlled mainly by topographic situations and warmth in summer. Adopting these statistic relationship between them as a model, we can simulate the influence of atomospheric warming on vegetation and landuse.
In the latter half of this paper we gave an overview about necessary functions of a data processing system for raster-type digital maps. And we described two examples of algorithms needed for efficient processing of drainage net structures in the DEM. The algorithms serves for runnoff prediction and drainage water budget analysis.
