Observation of hydrological processes and structures in the artificial Chicken Creek catchment

Hydrological catchments are the essential observation spaces for hydrological and ecological studies on a landscape scale. Generally, natural catchments are characterised by high complexity and heterogeneity with uncertainties in boundaries, interior structures and properties. Artificially created, spatially and structurally well-defined hydrological catchments might be a suitable tool for enabling progress in hydrological research. “Chicken Creek”, one of the largest artificial catchments, with clearly defined boundary conditions and extended monitoring facilities, was set up on a dump site associated with opencast mining activities in East Germany. This catchment, left to undisturbed succession, has enabled the observation of ecosystem development from its very beginnings. A sophisticated measurement concept covering hydrological, meteorological and soil physical parameters was designed. It aimed at the detection and description of the hydrological processes that form structures and are controlled by structures at the catchment scale. In mature natural catchments that have already achieved a stage of dynamic equilibrium with evolved runoff structures and land cover, hot spots of hydrological interest are normally known or easily identifiable prior to the establishment of any monitoring concept. For a newly created artificial catchment, there is no recorded experience regarding hydrological development and behaviour. Under the premise of looking at a defined, initially unstructured, homogenous, isotropic, “virgin” area, a primarily grid-based observation concept was chosen as the initial approach. As components of the progressive development of the ecosystem, new soil and runoff structures have been formed, and vegetation has spread on the initially uncovered surface. As a function of the changed hydrological properties and the improved system knowledge, the initial observation programme was iteratively extended and adjusted by the addition of more structure- and process-related installations. In this study, the design of the experimental observation set-up, the gathered experiences and the selected results of a large number of the most various hydrological data are presented. The combined analysis of measurement data and qualitative information worked to determine that the precipitation-induced surface runoff generation and the filling of the catchment storage were the main relevant hydrological processes in the initial development phase of the Chicken Creek catchment. Formed by the dominating surface runoff, erosion gullies are the most easily distinguishable structures influencing the runoff process. Despite the well-known catchment boundaries and the extensive monitoring, the catchment water balance has not been adequately closed so far. Due to the catchment’s properties (porosity, morphology, land cover), which are less homogeneous than initially assumed, the determination of the catchment’s evapotranspiration and changes in storage remains the challenge for understanding the Chicken Creek catchment.