AbstractThe Silala River basin is located in a remote area in the Andes Mountain range, where hydro‐meteorological and hydrogeological data are scarce. Consequently, the hydrological functioning of this river system was not well understood. Due to a dispute between Chile and Bolivia over the status and use of the waters of the Silala River, Chile requested the International Court of Justice to adjudge the Silala River system to be an international watercourse. To support the case, scientific studies were carried out in both countries to fill hydrological and hydrogeological knowledge gaps. This article reviews the Silala River basin topographic characterization, historical water use, and the dominant hydrological processes, and briefly summarizes an enhanced monitoring programme, reported in more detail elsewhere in this Special Issue. The longitudinal topographic profile and river slope show that Silala fluvial system is an exorheic watershed; waters from the Cajones and Orientals wetlands in Bolivia, the two headwater sources of the Silala fluvial system, naturally flow from Bolivia to Chile, demonstrating that the Silala River system is indeed an international watercourse. New hydro‐meteorological, hydrological and hydrogeological measurement stations were installed in both countries and provided improved process insights and spatiotemporal coverage within the basin. These new observations helped to populate hydraulic, hydrological, and hydrogeological models, aimed to improve understanding of the functioning of the system, including the effects of historical disturbance due to channelization of the Bolivian wetlands.This article is categorized under: Science of Water > Hydrological Processes Human Water > Rights to Water