Time filter

Source Type

Grabs W.,Federal Institute of Hydrology | Moser H.,International Commission for the Hydrology of the Rhine Basin
Water Policy | Year: 2015

This paper describes methods and processes to link policy development to the implementation of those policies in actionable implementation plans. It is shown that policies can only be implemented effectively if they are embedded in a legal framework that is designed to facilitate achievement of the policy objectives. The paper shows different levels of policy making and decision support for the development of policies at different levels, ranging from the level of Federal States in Germany to policy development and implementation at the European level as part of the European Framework Directive. Using the Elbe River as a case study, the paper shows the need to anchor regional, transboundary and state level policies to mandated national institutions. A key lesson learnt from the Elbe River Basin is that policy integration is of utmost importance. The paper also demonstrates that a balance needs to be reached with regard to structural and nonstructural measures in flood risk management to arrive at a truly integrated flood risk management strategy and its implementation. The development of research policies on the basis of sound science is indispensable in support of policy development and its implementation. © IWA Publishing 2015.

Hoffmann T.,Federal Institute of Hydrology | Hoffmann T.,University of Bonn
Earth-Science Reviews | Year: 2015

Growing empirical evidence shows that many geomorphic systems are in transient state or out of equilibrium with respect to the external driving forces. The transient state is often related to the (dis)connectivity of the many constituent parts of geomorphic systems as a result of sediment storage along the sediment flow path from its source to the final sink. The response time of geomorphic systems to external changes is thus dependent on the residence time of sediment in various storage compartments. Here, I present a mathematical concept based on reservoir theory to model residence time of sediment using millennial scale sediment budgets. The framework sheds light on the limitation of the sediment delivery ratio, which is often used as a measure of sediment connectivity in geomorphic systems, and provides analytical information on process type, pace of sediment flux and connectivity of storage compartments along the sediment cascade. The application of the reservoir theory to geomorphic systems under agricultural land use shows that sediment delivery ratios are linked to the virtual velocity of the eroded sediment, the time since the onset of agricultural land use and the size of the studied basins. With respect to the temporal evolution of sediment storages that temporarily remove sediment from the conveyor belt, the framework aims to estimate the sediment residence time in storages, which is linked to the effective time scale of disconnectivity. Reanalysis of a long-term empirical sediment budget from Central Europe reveals that the response to agricultural land use, which started ~5000yearsBP, is mainly buffered by the long residence time of sediment on hillslopes (in the order of 103years), which results in a delayed floodplain aggradation. Furthermore, the framework was applied to paraglacial mountain systems that inherit striking evidences of Pleistocene glacial erosion and still recover from the change from glacial to interglacial conditions as a consequence of the reduced lateral and longitudinal connectivity. I show that paraglacial response times of sediment flux in mountain headwater in the Canadian Rocky Mountains range in the order of 100-400ka. The results indicate that response times at the transition from glacial to interglacial conditions are much longer than the return interval of the major glaciations, causing a transient behavior of mountain headwater basins during interglacial periods. The presented reanalysis of millennial-scale sediment budgets of agricultural and mountain geosystems provides an integrative framework to link paleo-environmental reconstructions and the connectivity of transient geomorphic system to external changes. © 2015 Elsevier B.V.

Meermann B.,Federal Institute of Hydrology
Analytical and Bioanalytical Chemistry | Year: 2015

Abstract Since its introduction in the early 1990s, the on-line coupling of field-flow fractionation to inductively coupled plasma-mass spectrometry (FFF/ICP-MS) has evolved from a "niche" method into an established technique, especially in the field of natural-colloid analysis. Around the turn of the millennium engineered nanomaterials became prominent in research as a result of new properties, and in recent years FFF/ICP-MS has been revealed to be a promising tool for their analysis. Given the beneficial properties of this technique (e.g., no stationary phase, high separation power, multi-elemental capabilities, and high sensitivity) further applications, especially in the field of biomolecule analysis, will be discovered in the near future, and FFF will evolve further as a complementary tool to well-established chromatographic techniques (e.g. high-performance liquid chromatography, size-exclusion chromatography). The focus of this article is on recent application trends of FFF/ICP-MS, revealing the applicability of this technique within several fields of research, especially natural colloids and engineered nanoparticles. Possible future application trends, based on the author's opinion, are outlined in the "Concluding remarks and outlook" section. © 2015 Springer-Verlag Berlin Heidelberg.

Krausse T.,TU Dresden | Cullmann J.,Federal Institute of Hydrology
Hydrology and Earth System Sciences | Year: 2012

The development of methods for estimating the parameters of hydrologic models considering uncertainties has been of high interest in hydrologic research over the last years. In particular methods which understand the estimation of hydrologic model parameters as a geometric search of a set of robust performing parameter vectors by application of the concept of data depth found growing research interest. Bárdossy and Singh (2008) presented a first Robust Parameter Estimation Method (ROPE) and applied it for the calibration of a conceptual rainfall-runoff model with daily time step. The basic idea of this algorithm is to identify a set of model parameter vectors with high model performance called good parameters and subsequently generate a set of parameter vectors with high data depth with respect to the first set. Both steps are repeated iteratively until a stopping criterion is met. The results estimated in this case study show the high potential of the principle of data depth to be used for the estimation of hydrologic model parameters. In this paper we present some further developments that address the most important shortcomings of the original ROPE approach. We developed a stratified depth based sampling approach that improves the sampling from non-elliptic and multi-modal distributions. It provides a higher efficiency for the sampling of deep points in parameter spaces with higher dimensionality. Another modification addresses the problem of a too strong shrinking of the estimated set of robust parameter vectors that might lead to overfitting for model calibration with a small amount of calibration data. This contradicts the principle of robustness. Therefore, we suggest to split the available calibration data into two sets and use one set to control the overfitting. All modifications were implemented into a further developed ROPE approach that is called Advanced Robust Parameter Estimation (AROPE). However, in this approach the estimation of the good parameters is still based on an ineffective Monte Carlo approach. Therefore we developed another approach called ROPE with Particle Swarm Optimisation (ROPE-PSO) that substitutes the Monte Carlo approach with a more effective and efficient approach based on Particle Swarm Optimisation. Two case studies demonstrate the improvements of the developed algorithms when compared with the first ROPE approach and two other classical optimisation approaches calibrating a process oriented hydrologic model with hourly time step. The focus of both case studies is on modelling flood events in a small catchment characterised by extreme process dynamics. The calibration problem was repeated with higher dimensionality considering the uncertainty in the soil hydraulic parameters and another conceptual parameter of the soil module. We discuss the estimated results and propose further possibilities in order to apply ROPE as a well-founded parameter estimation and uncertainty analysis tool. © Author(s) 2012.

Meermann B.,University of Munster | Meermann B.,Federal Institute of Hydrology | Sperling M.,University of Munster | Sperling M.,European Virtual Institute for Speciation Analysis EVISA
Analytical and Bioanalytical Chemistry | Year: 2012

Method development and applications of hyphenated techniques as tools for speciation analysis of metalbased pharmaceuticals are summarized within this review. Advantages and limitations of the separation modes-highperformance liquid chromatography (HPLC), capillary electrophoresis (CE), and gas chromatography (GC)-as well as the detection modes-inductively coupled plasma-mass spectrometry (ICP-MS) and electrospray ionization-mass spectrometry (ESI-MS)-are discussed. ICP-MS detection is found to be advantageous for the quantification of drugs containing metals and other heteroatoms. The species-independent sensitivity and multielement capabilities of ICP-MS allow it to be used for quantification even when species-specific standards are not available, as well as to determine the stoichiometry in metallodrug-biomolecule interactions. Molecular information that is totally destroyed when ICP is applied as ionization source and is therefore not obtainable via ICP-MS detection can be accessed by the complementary technique of ESI-MS. Speciation analysis combining both elemental and molecular information is therefore a powerful tool for the analysis of metal-based pharmaceuticals and their metabolites in body fluids and other relevant matrices. © Springer-Verlag 2012.

Discover hidden collaborations