Investigation of hillslope-riparian-stream interactions: Monitoring, Modelling and Sensitivity analysis

• Applicant: Dr. Stephan Schulz, since 3/2023
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 459684982

Ever growing water demands and changing climatic conditions cause increasing pressure on surface water and groundwater resources. A rigorous quantitative understanding of the interactions and feedback mechanisms in the hydrological system is therefore essential for water management and water rights, nutrient loading from aquifers to streams, instream flow requirements for aquatic species, and the ecosystems that depend on them. This has created a need for an integrated coupled water flux modeling approach that can assess the surface water and groundwater interactions, as well as predict the impact of future changes in management and climate conditions. However, the investigation and quantification of the exchange processes and pathways in the hydrological systems are still a major challenge due to heterogeneities and the problem of integrating measurements at various scales. The general goal of this study is to obtain a better understanding how the riparian zone controls the transport of water from precipitation to the stream at the catchment scale. To this end, the existing interdisciplinary monitoring platforms, i.e. our Stettbach catchment, and the Wüstbach and Rollesbroich catchments of the TERENO project (www.tereno.net), that will provide us with high spatial and temporal resolution hydrological observations for the validation of the integrated fully coupled ParFlow-CLM model. In addition, the observed data set (i.e. soil water content and temperature, discharge, evapotranspiration, and water table depth) is essential for the sensitivity analysis, which is a critical approach to efficient separating these important parameters from the less sensitive ones. This information can be used to support and complement a model upscaling process by providing insights on how variations in the uncertain parameters. Furthermore, the comparison of the three catchments enables us to analyze the controlling factors of the hydrological processes across diverse environmental conditions (i.e. in terms of riparian zone, land use, geology, soil hydraulic properties, and climate conditions). Consequently, the processes that control hillslope-riparian-stream interactions will be investigated at different time scales (i.e. event scale, seasonal scale, and annual scale). More specifically, we will investigate the runoff generation processes by combining hydrometric measurements (e.g. discharge at different locations, groundwater levers and soil water distributions) and discriminate between different dominating processes. In addition, the transition between the hillslopes and riparian zone that controls both the dynamics of riparian saturation and streamflow generation, as well as the shallow groundwater response to subsurface stormflow and streamflow during rainfall events will be studied.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Christoph Schüth; Professor Dr. Harry Vereecken
• Ehemalige Antragstellerin: Dr. Wei Qu, until 2/2023