In this paper, we introduce the idea of documenting operational chains for land degradation assessment using ontologies. We believe that this will help end-users in better understanding the land degradation characteristics and evaluate the results of the assessment process. Since the application domain is wide, various operational chains for land degradation assessment and their associated documentation exist, according to different options. This parameterization causes the development of different ontologies, which, nonetheless are to a certain extent linked because of the common software components of the corresponding operational chains. We therefore propose a hierarchical structure of these ontologies; so that several requirements such as understanding of expert knowledge interconnections and application domain variety, documentation, assimilation of new expert knowledge, and reusability of software components become feasible.