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Abstract. Besides floodplains, hillslopes are basic units that mainly control water movement and flow pathways within catchments of subdued mountain ranges. The structure of their shallow subsurface affects water balance, e.g. infiltration, retention, and runoff. Nevertheless, there is still a gap in the knowledge of the hydrological dynamics on hillslopes, notably due to the lack of generalization and transferability. This study presents a robust multi-method framework of electrical resistivity tomography (ERT) in addition to hydrometric point measurements, transferring hydrometric data into higher spatial scales to obtain additional patterns of distribution and dynamics of soil moisture on a hillslope. A geoelectrical monitoring in a small catchment in the eastern Ore Mountains was carried out at weekly intervals from May to December 2008 to image seasonal moisture dynamics on the hillslope scale. To link water content and electrical resistivity, the parameters of Archie's law were determined using different core samples. To optimize inversion parameters and methods, the derived spatial and temporal water content distribution was compared to tensiometer data. The results from ERT measurements show a strong correlation with the hydrometric data. The response is congruent to the soil tension data. Water content calculated from the ERT profile shows similar variations as that of water content from soil moisture sensors. Consequently, soil moisture dynamics on the hillslope scale may be determined not only by expensive invasive punctual hydrometric measurements, but also by minimally invasive time-lapse ERT, provided that pedo-/petrophysical relationships are known. Since ERT integrates larger spatial scales, a combination with hydrometric point measurements improves the understanding of the ongoing hydrological processes and better suits identification of heterogeneities.

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The Ore Mountains were one of the important flood source areas for several heavy floods over the last years. Reducing damages caused by floods demands sufficient information on the runoff generation processes in the catchments. The aim of this study is to provide insights into prevailing flow pathways, retention times and threshold behavior of a representative hillslope catchment with layered subsurface in the Ore Mountains. The study site is a forested headwater with gneiss as bedrock. We used hydrometrical methods, soil temperature data and sprinkler experiments. Results indicate that the hydraulic anisotropic structure of the deepest layer in 0.9-1.7 m depth is the major controlling factor for subsurface water flow paths. On one hand, this layer acts as an aquitard for seeping water because of its high bulk density. On the other hand, water within the layer is able to flow laterally because of the sandy texture and coarse clasts oriented parallel to the slope. Moreover, three pre-moisture controlled types of runoff processes were addressed. With low antecedent soil moisture, saturation overland flow dominates in the spring bog. With intermediate or high pre-moisture, interflow is generated. The measured runoff coefficients increase in a nonlinear manner with rising pre-moisture. A soil water tension threshold value near field capacity is the tipping point for nonlinear runoff response. These findings emphasize the impact of the layered structure of the subsurface and of antecedent soil moisture for runoff generation in low mountain ranges and may be useful for establishing flood warning systems.

Reconstructing the evolution of arid landscapes is challenged by limited availability of appropriate environmental archives. A wide-spread surface feature -stone pavement -traps aeolian fines and forms a special accretionary archive. Seven stone pavement-covered sections on basalt flows in the eastern Mojave Desert are condensed to a composite section, comprising five sedimentological units, supported by an OSL-based chronology. Three of the units are of accretionary nature and each is covered by a stone pavement. They were deposited >50.9-36.6 ka, <36.6-14.2 ka and <14.2 ka and are intimately coupled with the history of nearby Lake Mojave, which advances the current picture of regional aeolian activity. End-member modelling analysis of grain-size distributions yielded seven sediment transport regimes. The accretionary system operates in two modes: A) episodic formation of a stone pavement by lateral processes once a vesicular horizon has formed on a barren surface and B) accretion of dust and eventually burial of the clast layer. These findings improve current concepts about stone pavement evolution and their environmental proxy function in arid landscapes. Stone pavement-covered accretionary deposits are a new key archive that allows quantifying the relative importance of dust accretion, slope processes, soil formation and vegetation cover.