Common problematic aspects of coupling hydrological models with groundwater flow models on the river catchment scale

Model coupling requires a thorough conceptualisation of the coupling strategy, including an exact definition of the individual model domains, the "transboundary" processes and the exchange parameters. It is shown here that in the case of coupling groundwater flow and hydrological models – in particular on the regional scale – it is very important to find a common definition and scale-appropriate process description of groundwater recharge and baseflow (or "groundwater runoff/discharge") in order to achieve a meaningful representation of the processes that link the unsaturated and saturated zones and the river network. As such, integration by means of coupling established disciplinary models is problematic given that in such models, processes are defined from a purpose-oriented, disciplinary perspective and are therefore not necessarily consistent with definitions of the same process in the model concepts of other disciplines. This article contains a general introduction to the requirements and challenges of model coupling in Integrated Water Resources Management including a definition of the most relevant technical terms, a short description of the commonly used approach of model coupling and finally a detailed consideration of the role of groundwater recharge and baseflow in coupling groundwater models with hydrological models. The conclusions summarize the most relevant problems rather than giving practical solutions. This paper aims to point out that working on a large scale in an integrated context requires rethinking traditional disciplinary workflows and encouraging communication between the different disciplines involved. It is worth noting that the aspects discussed here are mainly viewed from a groundwater perspective, which reflects the author's background

Conductance of electrolytes in 1-propanol solutions from −40 to 25°C

Conductance data for solutions of LiCl, NaBr, NaI, KI, KSCN, RbI, Et4NI, Pr4NI, Bu4NI, Bu4NClO4, n-Am4NI, i-Am4NI, n-Hept4NI, Me2Bu2NI, MeBu3NI, EtBu3NI, i-Am3BuNI, and i-Am3BuNBPh4 in 1-propanol at –40, –30, –20, –10, 0, 10, and 25°C are communicated and discussed. Evaluation of the data is performed on the basis of a conductance equation that includes a term in c3/2. Single ion conductances at 25 and 10°C are determined with the help of transference numbers t o + (KSCN/PrOH); the data are compared to data estimated by other methods. Ion-pair association constants and their temperature dependence are discussed in terms of contact and solvent separated ion pairs, and the role of non-coulombic forces is shown with the help of an appropriate splitting of the Gibbs energy of ion-pair formation

Environment of compact extragalactic radio sources

We have studied the interrelation of young AGN with their hosts. The objects of study are the young and powerful GPS and CSS radio sources. Due to their small size, GPS and CSS sources are excellent probes of this relation. Furhthermore, their young age allows us to compare them to the larger, old radio sources and establish a time-line evolution of this relation. Combining imaging and spectroscopy at UV, optical and radio wavelengths we find evidence of strong interaction between the host and the radio source. The presence and expansion of the radio source clearly affects the properties and evolution of the host. Furthermore, the radio source and host significantly affect each other's evolution. We describe our results and how these interactions take place.Comment: 6 pages. To appear in "Highlights of Spanisg astrophysics IV. Proceedings of the VII scientific meeting of the Spanish Astronomical Society". Editors: F. Figueras, J.M. Girart, M.Hernanz, C. Jordi. Springe

Phase diagram of an extended quantum dimer model on the hexagonal lattice

We introduce a quantum dimer model on the hexagonal lattice that, in addition to the standard three-dimer kinetic and potential terms, includes a competing potential part counting dimer-free hexagons. The zero-temperature phase diagram is studied by means of quantum Monte Carlo simulations, supplemented by variational arguments. It reveals some new crystalline phases and a cascade of transitions with rapidly changing flux (tilt in the height language). We analyze perturbatively the vicinity of the Rokhsar-Kivelson point, showing that this model has the microscopic ingredients needed for the "devil's staircase" scenario [E. Fradkin et al., Phys. Rev. B 69, 224415 (2004)], and is therefore expected to produce fractal variations of the ground-state flux.Comment: Published version. 5 pages + 8 (Supplemental Material), 31 references, 10 color figure

Conceptualization and implementation of a regional groundwater model for the Neckar catchment in the framework of an integrated regional model

International audienceJoint modelling of surface and subsurface systems is necessary to assess the quantity and quality of the water resources in a watershed. Therefore, it is widely applied in integrated regional models. The presented study deals with groundwater modelling within the framework of the integrated regional model MOSDEW, which is being developed for the Neckar catchment in Germany with the objective of contributing to the implementation of the EU Water Framework Directive (EU-WFD) (www.rivertwin.org). The groundwater model aims at obtaining a better understanding of the groundwater recharge processes and at evaluating the groundwater resources on watershed scale. In this paper the developed coupling method is described. Furthermore the groundwater model construction based on the available database and first calibration results are presented

Storage cascade vs. MODFLOW for the modelling of groundwater flow in the context of the calibration of a hydrological model in the Ammer catchment

International audienceHydrological models are the decisive tools to evaluate the effect of global change upon the water cycle. But the applied hydrological models have to be a trade-off between their degree of complexity and manageable structures and data requirements. This paper compares the advantages and disadvantages of integrating a spatially-distributed process-based groundwater flow model in the context of the calibration of a catchment runoff concentration model. The multi-objective optimisation and the GLUE method are used to analyse the performance and the parameter identifiability of both model structures

Probing the BLR in AGNs using time variability of associated absorption line

It is know that most of the clouds producing associated absorption in the spectra of AGNs and quasars do not completely cover the background source (continuum + broad emission line region, BLR). We note that the covering factor derived for the absorption is the fraction of photons occulted by the absorbing clouds, and is not necessarily the same as the fractional area covered. We show that the variability in absorption lines can be produced by the changes in the covering factor caused by the variation in the continuum and the finite light travel time across the BLR. We discuss how such a variability can be distinguished from the variability caused by other effects and how one can use the variability in the covering factor to probe the BLR.Comment: 12 pages, latex(aaspp4.sty), 2 figures, (To appear in ApJ

Ratchet effect in dc SQUIDs

We analyzed voltage rectification for dc SQUIDs biased with ac current with zero mean value. We demonstrate that the reflection symmetry in the 2-dimensional SQUID potential is broken by an applied flux and with appropriate asymmetries in the dc SQUID. Depending on the type of asymmetry, we obtain a rocking or a simultaneously rocking and flashing ratchet, the latter showing multiple sign reversals in the mean voltage with increasing amplitude of the ac current. Our experimental results are in agreement with numerical solutions of the Langevin equations for the asymmetric dc SQUID.Comment: 10 pages including 5 Postscript figure

Entanglement entropy in collective models

We discuss the behavior of the entanglement entropy of the ground state in various collective systems. Results for general quadratic two-mode boson models are given, yielding the relation between quantum phase transitions of the system (signaled by a divergence of the entanglement entropy) and the excitation energies. Such systems naturally arise when expanding collective spin Hamiltonians at leading order via the Holstein-Primakoff mapping. In a second step, we analyze several such models (the Dicke model, the two-level BCS model, the Lieb-Mattis model and the Lipkin-Meshkov-Glick model) and investigate the properties of the entanglement entropy in the whole parameter range. We show that when the system contains gapless excitations the entanglement entropy of the ground state diverges with increasing system size. We derive and classify the scaling behaviors that can be met.Comment: 11 pages, 7 figure

Using multi-objective optimisation to integrate alpine regions in groundwater flow models

International audienceWithin the research project GLOWA Danube, a groundwater flow model was developed for the Upper Danube basin. This paper reports on a preliminary study to include the alpine part of the catchment in the model. A conceptual model structure was implemented and tested using multi-objective optimisation analysis. The performance of the model and the identifiability of the parameters were studied. A possible over-parameterisation of the model was also tested using principal component analysis