Abstract: The study of the imperial town of Reutlingen explores the interactions between urban development, resource use, and riverine landscapes through the lens of the concept of fluvio-social metabolism. At its core is the tanning trade, whose key resource – oak bark – was integrated into the urban system via complex material and social flows. The study analyzes conflicts over forest resource use, particularly in the context of territorial disputes with Württemberg between the 14th and 16th centuries. It shows how the tannery district significantly shaped the topographical development of the urban floodplain. Fluvio-social metabolism serves as an interdisciplinary bridging concept for analyzing material cycles and institutional frameworks, embedded within a regional environmental history. The case study of Reutlingen forms part of the DFG-funded project “Local Pathways to the Fluvial Anthroposphere” and offers a nuanced view of locally embedded interventions in fluvial spaces. The study combines historical and archaeological approaches to investigate the long-term transformation of river landscapes at the intersection of society and nature. Keywords: Fluvio-social metabolism; Urban floodplain transformation; Resource conflicts; Tanning craft; Historical environmental change