Conquering Subsurface Stormflow (SSF)
DFG FundedFOR 5288: Fast and invisible: Conquering Subsurface Stormflow (SSF) through an Interdisciplinary Multi-Site Approach
Duration: 2026-2030 Current Phase: Phase II
Summary:
Researchers from various hydrological, ecological, and geological fields are working together focusing on subsurface stormflow (SSF), an important but difficult-to-measure process that strongly influences flood generation. SSF occurs under specific conditions and varies with soil, vegetation, and topography, making systematic study across landscapes essential. Through new measurement approaches, field studies in four test catchments (Sauerland, Black Forest, Ore Mountains, and the Alps), and close integration with modelling, the project aims to uncover the governing principles of SSF. These insights will support improved water management and flood protection strategies. The research unit consists of members from seven universities (Marburg, Freiburg, Berlin, Dresden, Innsbruck, Bayreuth, and Essen-Duisburg) and two research institutes (GFZ Potsdam, BFW Innsbruck) with cooperation partners in Switzerland, Italy, USA, and United Kingdom. The FOR has just entered a second funding phase, building on results from the first phase that demonstrated the potential of biological tracers to characterise subsurface source areas. This project aims to advance our ability to map subsurface flow paths, improve hydrological models, and better understand catchment connectivity, providing a new framework for tracing water movement in complex landscapes using naturally occurring biological signal.
Sub-project we are part of
Project F SSF Novel Tracers - Biogeochemical tracers (eDNA, DOC) and their transport and transformation across the hillslope–riparian–stream continuum
Understanding how water moves through soils and hillslopes before reaching streams is a major challenge in hydrology and fundamental to our understanding of flooding events. Key questions remain unresolved: Where does the water come from, how does it travel through the subsurface, and how do these pathways change over time? Traditional tracer methods can identify broad water sources and residence times, but lack the spatial precision needed to pinpoint exact flow path dynamics. SSF Novel Tracer explores an innovative biological tracer approach that combines environmental DNA (eDNA) and optical signatures of water-soluble organic matter (WSOM) to track subsurface flow paths at high spatial and temporal resolution. Different soil layers and landscape positions host distinct biological communities and organic matter signatures that persist over time. When soil water enters streams during storm events, these signatures can act as natural fingerprints of its origin.
By combining high-resolution eDNA metabarcoding with advanced optical analyses of dissolved organic matter, the project seeks to identify where in the soil profile and hillslope SSF is generated, how it connects to streams, and how these signals evolve during transport through riparian zones. Building on promising results from earlier work, the research now focusses on testing whether these biological signatures can be reliably detected in stream water and how they are altered by transport and transformation processes. The long-term goal is to incorporate these tracers into multi-objective hydrological models, improving our ability to map SSF and subsurface connectivity across catchments with unprecedented detail.
Involved in this Project: