The CASiMiR-vegetation model is a software that recreates the physical processes influencing the survival and recruitment of riparian vegetation, based on the relationship between ecologically relevant flow regime components and riparian vegetation metrics that reflect the vegetation’s responses to flow regime change. Working at a flow response guild level, this tool outperforms equivalent models by overriding various restrictions of the conventional modeling approaches. The potential of the CASiMiR-vegetation model is revealed in its application to different case studies during the development of a holistic approach to determine environmental flows in lowland Mediterranean rivers, based on woody riparian vegetation and fish species. Various modeling circumstances are described where CASiMiR-vegetation model was used with the purpose of sustaining the research addressing the thesis objectives. The main findings already accomplished in this research are highlighted to illustrate the outcomes that can be attained from the use of such a model.