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|Project head||Prof. Dr. Chris Soulsby
|Scientific assistants||Dr. Mikael
Christian Marx, M.Sc. 
|Project period||July 2019 - December
- Figure 1. Local natural and artificial influences on urban hydrology
- © Marx
As society increasingly demands higher environmental quality in urban areas for both human and ecological health, urban water resource systems need to be increasingly well understood and managed. The new requirement for urban planners to build resilience in the face of anticipated climate change only adds further urgency to this already pressing research need. Despite this, the hydrology of urban areas – that is, the processes of how water is routed and stored in this hybrid natural and technical system - is surprisingly poorly understood (Ehleringer et al. 2016).
Over the past two decades, isotope tracers have emerged as powerful integrating tools that have transformed our understanding of the hydrological cycle across spatial and temporal scales (Leibundgut et al. 2009). Isotopes are so effective in this regard because the relative abundance of stable isotopes (2H/1H and 18O/16O ratios) in water molecules act as “fingerprints” of water’s history in the hydrological cycle. This is due to the different behaviour of lighter isotopes (1H and 16O), which are preferentially selected in evaporation and melting, but selected against in condensation and precipitation.
The central thesis of the MOSAIC project is that stable water isotopes have the potential to transform our understanding of the hydrology and water resource systems of Berlin. The project focuses research around three research questions:
1. What are the isotopic characteristics of Berlin’s surface and subsurface waters?
2. How do different components of the urban landscape affect the isotopic composition of surface and ground waters?
3. How can this be used to understand how contrasting urban areas affect the partitioning of water flow paths, hydrological connectivity and travel times?
The project also aims to integrate modelling and field studies to critically assess the role of green spaces and the urban “critical zone” with regard to urban ecohydrological partitioning and the mitigation of the urban heat island effect. The project is financed through an Einstein Visiting Fellowship  granted to Prof. Dr. Chris Soulsby.
- Figure 2. Panke-Catchment in Berlin
- © Marx
The project focuses on three different spatial scales: plots, catchments and the entire cityscape. The plot scale will be investigated at a range of sites, including at an urban ecohydrological observatory in Steglitz in the south of Berlin, where an affiliated doctoral researcher from UWI  has sampled soil water and precipitation for stable isotope analysis. Together with data collected from an onsite eddy flux tower this provides a strong foundation for the spatially and temporally highly resolved ecohydrological model EcH2O-iso (Kuppel et al., 2018). The results of the modelling will help increase the process-based understanding of water partitioning and evaporation in urban catchments. An extensive sampling campaign in the urbanised River Panke (Fig. 2) in the northern part of the city will aim to answer how urbanisation affects isotopes in soil, surface and ground waters and deepen the understanding of ecohydrological partitioning at the catchment scale. Further upscaling across Berlin is envisaged in the latter stages of the project.
The project is well connected and situated into the local and international scientific landscape, including
- Research training group Urban Water Interfaces (UWI) 
for Freshwater Ecology and Inland Fisheries
Dr. Dörthe Tetzlaff , Dep. 1 Ecohydrology
- Prof. Dr. Dörthe Tetzlaff , Dep. 1 Ecohydrology
- Aberdeen University, Northern River Institute 
Ehleringer, J.R., Barnette, J.E., Jameel, Y., Tipple, B.J., Bowen, G.J., 2016. Urban water – a new frontier in isotope hydrology †. Isotopes in Environmental and Health Studies 52, 477–486. https://doi.org/10.1080/10256016.2016.1171217 
Kuppel, S., Tetzlaff, D., Maneta, M.P., Soulsby, C., 2018. EcH2O-iso 1.0: water isotopes and age tracking in a process-based, distributed ecohydrological model. Geoscientific Model Development 11, 3045–3069. https://doi.org/10.5194/gmd-11-3045-2018 
Leibundgut, C., Maloszewski, P. and Kuth, C., 2009. Tracers in Hydrology, Wiley