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Kotlarski S.,ETH Zurich | Hagemann S.,Max Planck Institute for Meteorology | Krahe P.,German Federal Institute of Hydrology | Podzun R.,Max Planck Institute for Meteorology | And 2 more authors.
Journal of Hydrology | Year: 2012

The regional climate model REMO extended by the HD river routing scheme (REMO-HD) is applied to the high-impact flooding event of August 2002 in the Elbe river basin. Both the ability of REMO to reproduce the observed precipitation pattern and the ability of the HD Model to translate the grid cell based runoff provided by REMO into streamflow are assessed. REMO-HD is operated with different settings and with different initialization fields but is always driven by the ECMWF operational analysis. The combined model system, operating at a spatial resolution of 18. km, is able to approximately capture the basic spatio-temporal patterns of precipitation and of river discharge during this particular event. Peak precipitation, however, is systematically underestimated. In detail, the performance depends on the specific configuration of the model system. In its optimal setup, REMO-HD is able to reproduce the timing and the magnitude of the flood peak at several gauging stations along the Elbe river despite the fact that the HD routing scheme was not explicitly calibrated for the catchment. A frequent re-initialization of REMO's atmospheric fields (forecast mode) slightly improves the simulation of precipitation but can also lead to local inaccuracies. The initialization procedure for soil moisture in the climate model is identified as a key element exerting a primary control on the simulated amounts of grid cell runoff and, consequently, on the simulated river discharge. The soil moisture initialization has only a limited influence on the simulated precipitation pattern. This indicates that the precipitation event has been primarily synoptically driven and that regional-scale land-atmosphere interactions involving evapotranspiration have been of no or only of minor importance. The results obtained increase our confidence in the potential of regional climate models extended by river routing schemes to be applied also for hydrological climate impact studies involving the analysis of extreme events. © 2012 Elsevier B.V..

Hagerbaumer A.,Bielefeld University | Hoss S.,Ecossa | Heininger P.,German Federal Institute of Hydrology | Traunspurger W.,Bielefeld University
Journal of Nematology | Year: 2015

With respect to their high abundances, their role as intermediaries between microorganisms and higher trophic levels, and their ubiquitous occurrence in all habitats, nematodes are of strong potential interest as environmental indicators. Ecotoxicological methods to evaluate the risk of anthropogenic pollutants on ecosystems require both in vitro and in vivo toxicity tests to investigate either mechanisms or pathways of toxicity and to set accurate toxicity thresholds. For this, the interest in nematodes as model organisms in ecotoxicology increased over the past few decades and existing appropriate experimental methods are reviewed in this manuscript. An overview of the various existing ecotoxicological tools for nematodes, ranging from molecular laboratory methods to experimental model ecosystem approaches, and their role as indicator organisms is given. The reviewed studies, approaches that range from species-based to community-based methods, reveal exciting possibilities for the future use of nematodes in ecotoxicological studies. Suitable ecotoxicological tools and ecological indices for nematodes should be integrated in weight-of-evidence approaches for assessing the ecological risk of contamination. © The Society of Nematologists 2015.

Benjankar R.,University of Idaho | Koenig F.,German Federal Institute of Hydrology | Tonina D.,University of Idaho
Journal of Hydrology | Year: 2013

Recent national and international legislation (e.g., the European Water Framework Directive) identified the need to quantify the ecological condition of river systems as a critical component for an integrated river management approach. An important defining driver of ecological condition is stream hydromorphology. Several methodologies have been proposed from simple table-based approaches to complex hydraulics-based models. In this paper, three different methods for river hydromorphological assessment are applied to the Boise River, United States of America (USA): (1) the German LAWA overview method (Bund/Laender Arbeitsgemeinschaft Wasser/German Working Group on water issues of the Federal States and the Federal Government represented by the Federal Environment Ministry), (2) a special approach for a hydromorphological assessment of urban rivers and (3) a hydraulic-based method. The hydraulic-based method assessed stream conditions from a statistical analysis of flow properties predicted with hydrodynamic modeling. The investigation focuses on comparing the three methods and defining the transferability of the methods among different contexts, Europe and West United States. It also provides comparison of the hydromorphological conditions of an urban and a rural reaches of the Boise River. © 2013 Elsevier B.V.

Bosshard T.,ETH Zurich | Carambia M.,German Federal Institute of Hydrology | Goergen K.,Center De Recherche Public Gabriel Lippmann | Kotlarski S.,ETH Zurich | And 3 more authors.
Water Resources Research | Year: 2013

The quantification of uncertainties in projections of climate impacts on river streamflow is highly important for climate adaptation purposes. In this study, we present a methodology to separate uncertainties arising from the climate model (CM), the statistical postprocessing (PP) scheme, and the hydrological model (HM). We analyzed ensemble projections of hydrological changes in the Alpine Rhine (Eastern Switzerland) for the near-term and far-term scenario periods 2024-2050 and 2073-2099 with respect to 1964-1990. For the latter scenario period, the model ensemble projects a decrease of daily mean runoff in summer (-32.2%, range [-45.5% to -8.1%]) and an increase in winter (+41.8%, range [+4.8% to +81.7%]). We applied an analysis of variance model combined with a subsampling procedure to assess the importance of different uncertainty sources. The CMs generally are the dominant source in summer and autumn, whereas, in winter and spring, the uncertainties due to the HMs and the statistical PP gain importance and even partly dominate. In addition, results show that the individual uncertainties from the three components are not additive. Rather, the associated interactions among the CM, the statistical PP scheme, and the HM account for about 5%-40% of the total ensemble uncertainty. The results indicate, in distinction to some previous studies, that none of the investigated uncertainty sources are negligible, and some of the uncertainty is not attributable to individual modeling chain components but rather depends upon interactions. ©2012. American Geophysical Union. All Rights Reserved.

Vanderford B.J.,Southern Nevada Water Authority | Drewes J.E.,Colorado School of Mines | Eaton A.,Eurofins | Guo Y.C.,Metropolitan Water District of Southern California | And 6 more authors.
Analytical Chemistry | Year: 2014

An evaluation of existing analytical methods used to measure contaminants of emerging concern (CECs) was performed through an interlaboratory comparison involving 25 research and commercial laboratories. In total, 52 methods were used in the single-blind study to determine method accuracy and comparability for 22 target compounds, including pharmaceuticals, personal care products, and steroid hormones, all at ng/L levels in surface and drinking water. Method biases ranged from <10% to well over 100% in both matrixes, suggesting that while some methods are accurate, others can be considerably inaccurate. In addition, the number and degree of outliers identified suggest a high degree of variability may be present between methods currently in use. Three compounds, ciprofloxacin, 4-nonylphenol (NP), and 4-tert-octylphenol (OP), were especially difficult to measure accurately. While most compounds had overall false positive rates of ≤5%, bisphenol A, caffeine, NP, OP, and triclosan had false positive rates >15%. In addition, some methods reported false positives for 17β-estradiol and 17α-ethynylestradiol in unspiked drinking water and deionized water, respectively, at levels higher than published predicted no-effect concentrations for these compounds in the environment. False negative rates were also generally <5%; however, rates were higher for the steroid hormones and some of the more challenging compounds, such as ciprofloxacin. The elevated false positive/negative rates of some analytes emphasize the susceptibility of many current methods to blank contamination, misinterpretation of background interferences, and/or inappropriate setting of detection/quantification levels for analysis at low ng/L levels. The results of both comparisons were collectively assessed to identify parameters that resulted in the best overall method performance. Liquid chromatography-tandem mass spectrometry coupled with the calibration technique of isotope dilution were able to accurately quantify most compounds with an average bias of <10% for both matrixes. These findings suggest that this method of analysis is suitable at environmentally relevant levels for most of the compounds studied. This work underscores the need for robust, standardized analytical methods for CECs to improve data quality, increase comparability between studies, and help reduce false positive and false negative rates. © 2013 American Chemical Society.

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