Uncovering the Slope Water Dynamics in the Layered Subsurface of Saprolite Dominated Landscapes: A Case Study from the Bavarian Forest, Germany

In the low and mid-mountain ranges of Central Europe, such as the vast Bavarian Forest, slopes are dominated by quaternary stratified Periglacial Slope Deposits (PSD), often underlain by saprolite. Previous research already pointed out that both PSDs and saprolite significantly impact the slope water movement and storage. In this study, in addition to slope water movement and intermediate storage in PSDs and saprolite, we investigate the transition to the active floodplain and the stream itself. From a geomorphological and pedological point of view, another focus is on the role of saprolite and loess, far outside the classic loess distribution areas.

The study area 20 km North of the City of Regensburg encompasses two catenae, each showing an upper slope planted with forest, a middle and toe slope covered with grassland, transitioning into a river floodplain that is also gras covered. The geomorphogenesis, soil genesis, and soil properties of these slopes are to be discussed as an essential basis for the work. Besides physicochemical analysis to characterize sediment and soil properties, also numerical dating techniques (OSL) are used. Furthermore, we use geophysical methods like ERT, SSR, and GPR to prospect the architecture of the shallow subsurface along the entire hillslope. Finally, we permanently instrumented each catena with, among other things, soil moisture probes and tensiometers. These are placed based on the position of particular sediment layers like PSDs, to highlight their differentiation and role in the slope water transport. The aim is to develop a model of the shallow subsurface, characterizing the pathways and temporary buffer of slope water under the given geomorphological conditions.