FOR 1598:  From Catchments as Organised Systems to Models based on Dynamic Functional Units - CAOS

• Subject Area: Geosciences
• Term: from 2011 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 182331427

Within phase 2 of the CAOS research unit we will work towards a holistic framework to explore how spatial organization alongside with spatial heterogeneity controls terrestrial water and energy cycles in intermediate scale catchments. 'Holistic' means for us to link the 'how' to the 'why' by drawing from generic understanding of landscape formation and biotic controls on processes and structures as well as to rely on exemplary experimental learning in a hypothesis and theory based manner. This also implies treatment of soil, vegetation and atmosphere as coupled system rather than a linear combination of different compartments. To jointly work towards this goal we propose 7 projects which will closely cooperate within two overarching work packages:WP1: Linking hydrological similarity with landscape structure across scalesWP2: Searching for appropriate catchment models and organizing principlesWithin WP1 we will further refine the existing stratified multi-method and multi-sensor setup to search for functional entities in the Attert and, if they exist, to learn in an exemplary manner which structural features control functional characteristics. This essentially includes identification of suitable metrics to discriminate functional and structural similarity from data as well as identification of useful quantitative descriptors for the rather fuzzy term 'hydrological function'. Overall we aim to synthesize a protocol to decide 'where to assess which data for what reasons' for characterizing hydrological functioning across a scale range of four orders of magnitude.Within WP2 we will foster our distillery of parsimonious and nevertheless physically consistent model structures which rely on observable quantities and make use of symmetries in the landscape to simplify the governing model equations in a hypothesis based manner. To this end we will compare concurring model structures (among those the CAOS model) and work towards a framework for an objective model inter comparison with special emphasis on a) the added value of different data/information sources and b) on consistency of predictions with respect to distributed dynamics and integral flows.Additionally, we aim in WP2 at linking the 'how' to the 'why' by synthesizing testable hypotheses that could explain whether spatial organization has evolved in accordance with candidate organizing principles. Ecology, fluvial geomorphology and thermodynamics offer a large set of candidate organizing principles for this issue. Based on our recent work we will focus especially on thermodynamic limits and optimality principles like maximum entropy production, explore their value for uncalibrated hydrological predictions and work out the necessary requirements on data and models for testing these principles. We put special emphasis on a possible experimental falsification of these candidate principles; also in close collaboration with the B2-Landscape Evolution Observatory in Tucson, Arizona.

• DFG Programme: Research Units
• International Connection: Austria, Luxembourg, United Kingdom

Projects

• An adaptative process based model framework for water-, energy- and mass cycles in lower mesoscale catchments (Applicant Zehe, Erwin )
• Dynamic patterns of land-surface characteristics related to water/energy fluxes at the hillslope and small catchment scale using remote sensing (Applicants Schulz, Karsten ;  Udelhoven, Thomas )
• Feedbacks between soils, biota, land management and hydrological processes at different spatiotemporal scales (Applicants van Schaik, Loes ;  Schröder-Esselbach, Boris )
• From subsurface structures to functions and texture - linking virtual realities and experiments at the plot and hillslope scales (Applicant Zehe, Erwin )
• Hydrological connectivity and its controls on hillslope and catchment scale stream flow generation (Applicants Blume, Theresa ;  Weiler, Markus )
• Linking landscape structure and rainfall runoff behaviour in a thermodynamic optimality context (Applicant Zehe, Erwin )
• Non-invasive geophysical and remote sensing methods to map and characterize relevant structures and processes (Applicants Hinz, Stefan ;  Tronicke, Jens )
• Quantitative Precipitation Estimation (QPE) by exploiting the potential of advanced radar observations and data assimilation (Applicants Ehret, Uwe ;  Görgen, Klaus ;  Wulfmeyer, Volker )
• Spatio-temporal dynamics of water storage, mixing and release (Applicants Blume, Theresa ;  Pfister, Laurent ;  Weiler, Markus )
• The use of thermodynamics and optimality theory for modelling soil-vegetation-atmosphere transfer (SVAT) processes at different scales (Applicant Kleidon, Axel )
• Towards consistent predictions of water and energy cycles in intermediate scale catchments (Applicants Ehret, Uwe ;  Zehe, Erwin )
• Understanding and characterizing land surface-atmosphere exchange and feedbacks (Applicants Kleidon, Axel ;  Mallick, Kaniska ;  Schulz, Karsten ;  Wulfmeyer, Volker )
• Understanding and interpretation of catchment behaviour with a top down approach. Further development of flexible modul structures for hypothesis testing (Applicant Fenicia, Fabrizio )

• Partner Organisation: Fonds National de la Recherche; Fonds zur Förderung der wissenschaftlichen Forschung (FWF)
• Spokespersons: Professor Dr. Laurent Pfister, from 1/2015 until 12/2018; Professor Dr.-Ing. Erwin Zehe, until 12/2018
• Participating Persons: Dr.-Ing. Uwe Ehret; Dr. Kaniska Mallick; Dr. Martin Schlerf; Professor Dr. Karsten Schulz; Dr. Ivonne Trebs