To address the challenges of global change, interdisciplinary and integrated research in terrestrial environmental science at multiple temporal and spatial scales is of great importance. Several environmental research networks have already been established in order to monitor, analyse and predict the impact of global change on different compartments and/or water and matter cycles of the environment. Typically these environmental research networks have focused on specific research questions and compartments, such as FLUXNET and ILTER. At present other initiatives like ICOS, Lifewatch, and ANAEE are emerging, each of them focussing on specific research questions. We argue that there is a need to establish a network of hydrological observatories, defined as a system of systems consisting of the subsurface environment, the land surface including the biosphere, the lower atmosphere as well as socioeconomic aspects. In order to spur on and move forward all fields of hydrological research in particular. Although terrestrial systems are extremely complex, the hydrological component in larger scale process-based climate and biosphere models is often represented in a very conceptual and often rudimentary way. Addressing this issue is therefore one of the most important challenges in hydrological research, and we suggest that hydrological observatories could play an important role. Hydrological observatories create unprecedented data sets by integrating existing and new measurement technologies such as remote sensing platforms, hydrogeophysical measurement techniques and wireless sensor networks that will significantly improve our understanding of hydrological processes. We solicit contributions related but not limited to the following topics:
(i) Different measures on eco-hydrological processes in the experimental basins identified by field measurements
(ii) analysis of hydrological patterns at different scales and recent ongoing measurements in the experimental river basins
(iii) methods for the evaluation, visualisation and interpretation of hydrological data sets (e.g. runoff, soil moisture, micrometeorology, groundwater)
(iv) unusual and unexpected hydrological phenomena identified by measurements that could not be explained by existing theoretical considerations
(v) gaps in knowledge on integrated basin responses to present and future anthropogenic and/or climate impacts