In order to reduce damage due to floods and debris flows, not only preventive measures but also interventions such as temporary deflection dikes are required. This challenge of emergency management may be met largely by an early warning system. IFKIS-Hydro is an information and warning system for hydrological hazards in small and medium scale catchments. It collects data such as weather forecasts, precipitation measurements, discharge simulations and local observations. In addition, IFKIS-Hydro incorporates a web-based information-platform called InfoManager, which serves as a central hub for the submission and oversight of the data. Special emphasis ought to be given to local information. This is gathered by measuring stations in more remote areas on the one hand, and by observers on the other hand. The inclusion of specialised local personnel is a must as they have much responsibility, both for the interpretation of the data and the realization of the intervention.