CATENA Vol. 8, 239-249 Braunschweig 1981 A COMPARISON OF MANUAL AND AUTOMATED SLOPE MAPS G.Engelen & W. Huybrechts, Brussels SUMMARY The authors propose an automated method of generating slope maps. Starting from a topographical map, a Digitized Terrain Model is build up and completed with a'morphologic- al matrix'. By determining the representative slope for each grid cell an impression of the geo- graphical distribution of the different slope values is obtained. In two test areas in Dry Hesbaye (E. Belgium), where the results were compared with a detailed manually constructed slope map, the applicability and advantages of the method for general purposes are demontrated. 1. INTRODUCTION In geomorphological research, the investigation ofslopes is frequently quite significant. It is often performed by means of slope maps. Several authors have described manual methods of constructing slope maps from pub- lished topographic maps. This article describes an automated method developed by the authors. Although it is possible for a detailed automated slope map to be compiled completely by means of modern technical methods and a thorough preparation of the topographic source map, the average investigator does not have at his disposal the necessary sophisticated digiti- zers, calculating and drawing equipment. In addition, a prolonged map preparation reduces the advantages of the automated method. These restrictions were given main considerations in this study which also considers the extent to which detailed hand-made slope maps can be approached. 2. METHOD 2.1. In the method to be followed four phases may be distinguished, of which the first two phases are manual and preparatory and the second two, computing (3) and com- pilation (4) of the slope values, are fully automatic. Feedbacks between the distinct steps may be necessary. In the initial phase, a source map has to be carefully selected for the study area at an appropriate scale, taking into account the morphology of the area on the one hand and the research objectives on the other.