The hydrological research within the Harz/Central German Lowland Observatory is concentrated in the catchment area of the river Bode (catchment size approx. 3.300 km²). The detection of scale dependencies in flowpaths, run-off generation or residence times requires scale-related approaches of observation. Therefore, a nested approach including small process plots (< 2 km²), meso-scale subcatchments (approx. 100 km²) up to the scale of the complete Bode catchment will be established. A more detailed description of the hydrological observatory and the several intensive test sites can be found at www.tereno.net.