McHarg's "Design With Nature" was a precursor of the layer model in modern geographic information systems. We are reviewing the layer overlay approach from a geospatial data infrastructure (GDI) perspective and experiment with weighted map overlay using Web map services. A case study for natural hazard risk assessment for Southern Quebec illustrates this visual approach to multi-criteria analysis using online mapping. We conclude with a call for more research on thematic mapping and its use for decision support within GDIs.

McHarg's "Design With Nature" was a precursor of the layer model in modern geographic information systems. We are reviewing the layer overlay approach from a geospatial data infrastructure (GDI) perspective and experiment with weighted map overlay using Web map services. A case study for natural hazard risk assessment for Southern Quebec illustrates this visual approach to multi-criteria analysis using online mapping. We conclude with a call for more research on thematic mapping and its use for decision support within GDIs.

This work introduces concepts from usability engineering and user centered design into software development in the educational context. As still most digital geomedia on the educational market are based on classical GIS principles made for professionals there is a need for usable tools that fit the needs of students and teachers. A prototype WebGIS application for schools to present various geospatial datasets with an intuitive user interface will be presented. The used technologies and GUI elements are described. Usability tests with secondary school students are conducted and are used to assess the performance of the prototype web application in a realistic environment.