 The proposed method for expressing geographic information systems, GIS, workflows as linked data allows GIS analysts to organize their methods on spatial data in complex chains, easily publish them on the web, query them for types of inputs, results, or tools, and reuse them in a modular way by selecting, adapting, and recommending resources based on compatible semantic types. The method uses an OWL typing scheme and SPARQL rules to propagate data types and implicit semantic structures through the workflow, and is implemented in Python and evaluated on two real-world geo-processing workflows generated with SRS-UP GIS. Competency questions are formulated and executed over these workflows to illustrate the potential applications of the typing method. This article was authored by Simon Scheider and Andrea Ballator.