Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 7 2009 10.5194/hess-13-1215-2009 http://www.hydrol-earth-syst-sci.net/13/1215/2009/ http://www.hydrol-earth-syst-sci.net/13/1215/2009/hess-13-1215-2009.html http://www.hydrol-earth-syst-sci.net/13/1215/2009/hess-13-1215-2009.pdf 1215 1233 2009-07-17 Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes T. Blume blume@gfz-potsdam.de E. Zehe A. Bronstert Institute for Geoecology, Section of Hydrology and Climatology, University of Potsdam, Germany Helmholtz Centre Potsdam, GFZ German Research Centre for Geosciences, Germany Institute for Water and Environment, Technical University Munich, Germany Invited contribution by T. Blume, one of the EGU Young Scientists' Outstanding Poster Paper (YSOPP) Award winners 2008. Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope scale). Annual dynamics of soil moisture and decimeter-scale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a data-scarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. 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