Two-dimensional modeling of hydraulics and fine sediment transport during extreme floods in urban areas

Treffen Extremhochwässer auf urbane Räume, können sie große Schäden verursachen. Um in diesen Gebieten Gefahren rechtzeitig zu erkennen, geeignete Maßnahmen zu ergreifen und im Fall einer Katastrophe Einsatzkräfte und Technik effizient koordinieren zu können, werden Entscheidungshilfesysteme unterstützend eingesetzt. Hydraulische Modelle bilden mit den Vorhersagen der Wasserstände, Fließgeschwindigkeiten und Flächenausdehnung der Überflutungen die wichtigste Grundlage für diese Entscheidungshilfesysteme. Ziel dieser Arbeit ist es, ein hydraulisches 2D-Modell mit dem für urbane Gebiete notwendigen Detaillierungsgrad aufzubauen und trotz der Daten-, Prozess- und Parameterunsicherheiten ein darauf basierendes Schadstoffausbreitungsmodell zu erstellen, für ein Extremhochwasser zu kalibrieren, mit diesem Modellsystem Simulationen durchzuführen, die Ergebnisse zu analysieren und sie in ein Entscheidungshilfesystem zur stoffbezogenen Risikoanalyse und -bewertung extremer Hochwasserereignisse zu integrieren. Im Rahmen einer Fallstudie an der Vereinigten Mulde im Raum Bitterfeld wird für ein 45 km2 großes Gebiet ein detailliertes Modellsystem aufgebaut. Durch die nachträgliche Vermessung von Flutmarken der maximalen Wasserstände des Extremhochwassers vom August 2002 werden die notwendigen Daten zur Kalibrierung des hydraulischen Modells generiert. Zur Validierung des Sedimenttransportmodells wird ein ereignisunabhängiges neuartiges semi-quantitatives Verfahren entwickelt. Als Ergebnisse stehen räumlich und zeitlich hoch aufgelöste Wasserstände, Fließgeschwindigkeiten, Depositionshöhen und Konzentrationen von partikulär gebunden transportierten Stoffen zur Verfügung. Diese Daten werden für Risikobewertungen in einem Entscheidungshilfesystem genutzt und in Form von Karten präsentiert. Das Entscheidungshilfesystem hat sich im Praxiseinsatz bei Extremhochwässern bewährt, wobei der Schwerpunkt bislang auf den Ergebnissen der hydraulischen Modellierung lag.Climate change research predicts that extreme floods will occur more frequently in future. Floods in urban areas result in catastrophic consequences. Decision support systems (DSS) requires to identify and estimate the impact of impending flood in advance and to take suitable measures for the efficient coordination of operational forces and technique. Hydraulic models are the most important basis for such DSS. The aim of this study is to develop a high resolution 2D hydraulic model for urban areas and to couple it with a sediment and pollutant transport model. The model system is then calibrated for an extreme flood. Simulations are performed and the results are analyzed and integrated in a DSS for risk analysis and assessment of extreme floods. The aforementioned high resolution 2D hydraulic model is applied for the case study of the River Mulde adjoining the City Bitterfeld covering an area of 45 square kilometer. The necessary data for calibration of the hydraulic model are generated by additional survey of flood marks of the maximum water level during the extreme flood of August 2002. A new approach for validation of the sediment transport model is developed. Spatially and temporarily high resolution results of surface water levels, flow velocities, deposition and concentrations of particular bounded pollutants are presented for different scenarios. The results are used for risk assessment in the DSS and are presented as maps. The integrated DSS has been approved and used by authorities where the focus was on hydraulic results. The presented approach for the development of an integrated DSS based on the results of 2D hydraulic modeling combined with sediment and pollutant transport can be transferred to other urban areas after necessary modifications

Emergent spatial patterns of competing benthic and pelagic algae in a river network: A parsimonious basin-scale modeling analysis.

Algae, as primary producers in riverine ecosystems, are found in two distinct habitats: benthic and pelagic algae typically prevalent in shallow/small and deep/large streams, respectively. Over an entire river continuum, spatiotemporal patterns of the two algal communities reflect specificity in habitat preference determined by geomorphic structure, hydroclimatic controls, and spatiotemporal heterogeneity in nutrient loads from point- and diffuse-sources. By representing these complex interactions between geomorphic, hydrologic, geochemical, and ecological processes, we present here a new river-network-scale dynamic model (CnANDY) for pelagic (A) and benthic (B) algae competing for energy and one limiting nutrient (phosphorus, P). We used the urbanized Weser River Basin in Germany (7th-order; ~8.4 million population; ~46 K km2) as a case study and analyzed simulations for equilibrium mass and concentrations under steady median river discharge. We also examined P, A, and B spatial patterns in four sub-basins. We found an emerging pattern characterized by scaling of P and A concentrations over stream-order ω, whereas B concentration was described by three distinct phases. Furthermore, an abrupt algal regime shift occurred in intermediate streams from B dominance in ω≤3 to exclusive A presence in ω≥6. Modeled and long-term basin-scale monitored dissolved P concentrations matched well for ω>4, and with overlapping ranges in ω<3. Power-spectral analyses for the equilibrium P, A, and B mass distributions along hydrological flow paths showed stronger clustering compared to geomorphological attributes, and longer spatial autocorrelation distance for A compared to B. We discuss the implications of our findings for advancing hydro-ecological concepts, guiding monitoring, informing management of water quality, restoring aquatic habitat, and extending CnANDY model to other river basins

Iron Exports From Catchments Are Constrained by Redox Status and Topography

Fe(III) hydroxides stabilize organic carbon (OC) and P in soils. Observations of rising stream Fe concentrations are controversially posited to result from a flushing of iron-rich deeper soil layers or a decrease of competing electron acceptors inhibiting Fe reduction (NO3- and SO42-). Here, we argue that catchment topography constrains the release of Fe, OC, and P to streams. We therefore incubated organic topsoil and mineral subsoil and modified the availability of NO3-. We found that Fe leaching was highest in topsoil. Fe, OC, and P released at quantities proportional to their ratios in the source soil. Supply of NO3- reduced Fe leaching to 18% and increased pore water OC:Fe and P:Fe ratios. Subsoil, however, was an insignificant Fe source (<0.5%). Here, the leached quantities of Fe, OC and P were highly disproportionate to the soil source with an excess of released OC and P. We tested if experimental findings scale up using data from 88 German catchments representing gradients in NO3- concentration and topography. Average stream Fe concentrations increased with decreasing NO3- and were high in catchments with shallow topography where high groundwater levels support reductive processes and topsoils are hydrologically connected to streams; but Fe concentrations were low in catchments with steep topography where flow occurs primarily through subsoils. OC:Fe and P:Fe ratios in the streams similarly varied by NO3- and topography. This corroborates the findings from the laboratory experiment and suggests that catchment topography and competing electron acceptors constrain the formation of Fe-reducing conditions and control the release of Fe, OC, and P to streams. © 2022. The Authors

QUADICA: Water quality, discharge and catchment attributes for large-sample studies in Germany

Environmental data are the key to define and address water quality and quantity challenges at catchment scale. Here, we present the first large-sample water quality data set for 1386 German catchments covering a large range of hydroclimatic, topographic, geologic, land use and anthropogenic settings. QUADICA (water QUAlity, DIscharge and Catchment Attributes for large-sample studies in Germany) combines water quality with water quantity data, meteorological and nutrient forcing data, and catchment attributes. The data set comprises time series of riverine macronutrient concentrations (species of nitrogen, phosphorus and organic carbon) and diffuse nitrogen forcing data at catchment scale (nitrogen surplus, atmospheric deposition and fixation). Time series are generally aggregated to an annual basis; however, for 140 stations with long-term water quality and quantity data (more than 20 years), we additionally present monthly median discharge and nutrient concentrations, flow-normalized concentrations and corresponding mean fluxes as outputs from weighted regressions on time, discharge, and season (WRTDS). The catchment attributes include catchment nutrient inputs from point and diffuse sources and characteristics from topography, climate, land cover, lithology and soils. This comprehensive, freely available data collection can facilitate large-sample data-driven water quality assessments at catchment scale as well as mechanistic modeling studies

QUADICA: A large-sample data set of water quality, discharge and catchment attributes for Germany

Environmental data are critical for understanding and managing ecosystems, including mitigation of degraded water quality. Therefore, we provide the first large-sample water quality data set of riverine water quality combined with water quantity, meteorological and nutrient forcing data, and catchment attributes for Germany in a preprocessed and structured form. The QUADICA data set (water QUAlity, DIscharge and Catchment Attributes for large-sample studies in Germany) covers 1386 German and transboundary catchments with a large range of hydroclimatic, topographic, geologic, land use and anthropogenic settings. The data set comprises time series of riverine macronutrient concentrations (species of nitrogen, phosphorus and organic carbon), discharge, meteorological and diffuse nitrogen forcing data (nitrogen surplus, atmospheric deposition and fixation). The time series are generally aggregated to an annual basis; however, for 140 stations with long-term water quality and quantity data (more than 20 years), we additionally provide monthly median discharge and nutrient concentrations, flow-normalized concentrations and corresponding mean fluxes as outputs from weighted regressions on time, discharge, and season (WRTDS). The catchment attributes include catchment nutrient inputs from point and diffuse sources and characteristics from topography, hydroclimate, land cover, lithology and soils. QUADICA is a comprehensive, freely available, ready-to-use data set that facilitates large-sample data-driven water quality assessments at catchment scale as well as mechanistic modeling studies. We hope to stimulate the hydrological and water quality communities to provide similar data sets to create novel research opportunities, increase our understanding of catchment functioning, and ultimately improve water quality management

Sarcoma classification by DNA methylation profiling

Sarcomas are malignant soft tissue and bone tumours affecting adults, adolescents and children. They represent a morphologically heterogeneous class of tumours and some entities lack defining histopathological features. Therefore, the diagnosis of sarcomas is burdened with a high inter-observer variability and misclassification rate. Here, we demonstrate classification of soft tissue and bone tumours using a machine learning classifier algorithm based on array-generated DNA methylation data. This sarcoma classifier is trained using a dataset of 1077 methylation profiles from comprehensively pre-characterized cases comprising 62 tumour methylation classes constituting a broad range of soft tissue and bone sarcoma subtypes across the entire age spectrum. The performance is validated in a cohort of 428 sarcomatous tumours, of which 322 cases were classified by the sarcoma classifier. Our results demonstrate the potential of the DNA methylation-based sarcoma classification for research and future diagnostic applications

Les Heures d'Etienne Chevalier.

Büttner Frank Olaf. Les Heures d'Etienne Chevalier. In: Scriptorium, Tome 29 n°1, 1975. pp. 84-106

Millard Meiss. The De Lévis Hours and the Bedford Workshop. New-Haven, 1972

Büttner Frank Olaf. Millard Meiss. The De Lévis Hours and the Bedford Workshop. New-Haven, 1972. In: Scriptorium, Tome 30 n°1, 1976. pp. 116-119

Nigel Morgan. Early Gothic Manuscripts (I), 1190-1250

Büttner Frank Olaf. Nigel Morgan. Early Gothic Manuscripts (I), 1190-1250. In: Scriptorium, Tome 37 n°1, 1983. pp. 143-145

Bernard Gagnebin. L'enluminure de Charlemagne à François Ier. Les manuscrits à peintures de la bibliothèque publique et universitaire de Genève.

Büttner Frank Olaf. Bernard Gagnebin. L'enluminure de Charlemagne à François Ier. Les manuscrits à peintures de la bibliothèque publique et universitaire de Genève.. In: Scriptorium, Tome 33 n°1, 1979. pp. 91-92