Quality assessment of the Corine Land Cover 2000 Data Base in Spain

Abstract

The CORINE Land Cover project provides basic information for the analysis of space and land in the European Union. The use of the European Land Cover database in environmental applications implies an updating process that enables the provision of the appropriate information required to obtain land cover change indicators. The EU member states expressed the need for an update as support for the current and future Environmental Policy, as well as a reliable tool in the evaluation of the policy carried out regarding this matter during the last decade. The EEA took the initiative to update CORINE Land Cover: IMAGE & CORINE LAND COVER 2000 project (I&CLC2000) and the preparatory work for updating the CLC database (I&CLC2000 project) began in 1999.

To evaluate the quality of the Land Cover Database of the CORINE Land Cover 2000 project, it is necessary to validate the various products which make up that database. A selection was made among several possible statistical sampling techniques, opting for stratified random sampling. In the case of the Land Cover for the year 2000, the strata are made up of the 44 level 3 classes, in accordance with European nomenclature. They were distributed in such a way as to ensure that the samples selected are shared proportionally in each of the Autonomous communities in order to have data concerning each of them. For the database on changes taking place between 1990 and 2000, the strata are the change polygons and the non-change ones. The sample size in each case has been calculated after establishing the level of confidence and the estimate of the percentage of correct answers for the data. The reference information used to carry out the validation are the Landsat images belonging to the CORINE Land Cover 90 and 2000 projects, together with aerial orthophotography.