Historical perspectives on river restoration design in the USA

River restoration as a science needs to balance numerical analysis with a more general systems understanding typical of a classification-based approach. We show the need for this balance by comparing the Davis-Gilbert debate in physical geography to the current 'Rosgen wars' (Lave, 2008) in fluvial geomorphology and river restoration. In both controversies, one perspective was accepted for a period of time, but then subsequently vilified by vocal members of the discipline. However, in the process of replacing one paradigm with another, former viewpoints are often misrepresented and set up as contradictory to the newer paradigm. Careful reconsideration of Gilbert's and Davis' approaches to geomorphology shows them not as mutually exclusive, but rather as complementary. Observation and nomenclature, as well as measurement and process analysis, are not only parts of the general temporal progression of a discipline, but are complementary scientific approaches. Davis' nomenclature and Gilbert's analytical processes are both necessary to understand and discuss landscape geomorphology. Similarly, both Rosgen's classification system, or one like it, and other more analytical, process-based examinations, are necessary for a comprehensive approach to river restoration. It is clear that multiple viewpoints and approaches triangulate towards a more thorough understanding of a system and will increase the probability of successful restoration. This will most likely include system-wide observation and classification married to numerical process modeling.