Quantifying changes in stream-landscape connectivity: combining high-resolution data of non-perennial streams and environmental tracers
- 1EPF Lausanne, Environmental Engineering Institute IIE, School of Architecture, Civil and Environmental Engineering ENAC, Lausanne, Switzerland
- 2Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Mountain Hydrology and Mass Movements, Birmensdorf, Switzerland
- 3Università di Padova, Department of Civil, Environmental and Architectural Engineering (DICEA), Padova, Italy
- 4University of Zurich, Department of Geography, Zurich, Switzerland
Changes in hydrologic connectivity between streams and the surrounding landscape are among the most important factors that control the temporal variation in streamwater chemistry. In most headwater catchments, the dynamic expansion and contraction of the non-perennial stream network affects and reflects this hydrologic connectivity. Until now, however, the spatiotemporal variations of non-perennial stream networks have been mapped only sporadically and environmental tracer data to explore the dynamic connectivity for these streams are lacking.
Within the TempAqua project, we have monitored the temporal variation in environmental tracers (solutes, stable water isotopes) in precipitation, soil- and groundwater, as well as in stream water during rainfall events in the pre-Alpine Erlenbach catchment. We combine these measurements with novel, sub-hourly data on stream network expansion and contraction.
Our data show that the total flowing stream length increased rapidly, up to 10-fold, during individual rainfall events. Changes in solute concentrations in streamwater indicate that different water stores become dynamically connected to the stream and disconnect again during subsequent dry periods: at the beginning of an event, the dilution of sulphate and calcium suggest a surface runoff contribution of rainwater at the time of rapid expansion of the network and increasing discharge. As rainfall continues, the stream network expands further due to rising groundwater tables, which is indicated by increased nitrate and sulphate concentrations in the stream. The magnitude and importance of these processes depends more on antecedent wetness conditions than event magnitude.
Our observations shed light onto the short-term mechanisms by which non-perennial streams start to flow during rainfall events, and provide new knowledge to address emerging questions on the functional relationships between stream-landscape connectivity, hydrological responses and water quality in headwater catchments, and their vulnerability to global climate change.
How to cite: von Freyberg, J., Bujak, I., Rinaldo, A., and van Meerveld, I.: Quantifying changes in stream-landscape connectivity: combining high-resolution data of non-perennial streams and environmental tracers , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14005, https://doi.org/10.5194/egusphere-egu23-14005, 2023.
