MAPPING OF LAND UNITS AND LAND CAPABILITY CLASSIFICATION IN PORTUGAL. THE CASE OF THE MUNICIPALITY OF LOURINHÃ

Resumo

Land units can be an advantageous tool in landscape planning, in land suitability and land capability classification. It is vital to deepen the knowledge on their delimitation procedures, particularly in areas where available data is scarce and presents a certain complexity. Lourinhã municipality, based on sedimentary rocks, was chosen as a case study. Land units were mapped using geology (1:50 000), landforms and soils (1:25 000) information. Several inadequacies were observed both in the soil and soil capability maps.  There was evidence of a strong information deficiency on basic characteristics of soil units and the rockiness was not revealed in such maps. From the geological units and landforms, 33 basic physiographic units were delimited, and their association with soil units resulted in an equal number of land units, afterwards generalized. The delimited land units have proven to be suitable for a land capability classification at the municipality scale, revealing great potential to identify the nature and severity of the major land (and soil) degradation risks. Also, they showed to be useful for improvement of the soil capability classificationⁱ and to standardize the definition of the National Agricultural Reserve by using identical delimitation criteria.