Hydromechanik. Übungsaufgaben [online]

Die dargestellten Übungsaufgaben stellen nur eine kleine Sammlung vieler Möglichen Beispiele dar, mit der das Verständnis der Hydromechanik geprüft, unterstützt und trainiert werden kann. Es ist sehr hilfreich diese parallel zur Vorlesung in den Tutorien und auch zuhause durchzurechnen und aufkommende Fragen in den Lehrveranstaltungen mit dem Dozenten oder den Betreuern zu diskutieren

Environmental quality standards in the EC-water framework directive: consequences for water pollution control for point sources

The "combined approach" in the new EC-Water Framework Directive (WFD) consisting of environmental quality standards in addition to emission limit values promises improvements in the quality characteristics of surface waters. However, the specification of where in the water body the environmental quality standards apply is missing in the WFD. This omission will limit its administrative implementation. A clear mixing zone regulation is needed so that the quality objectives of the WFD are not jeopardized. This need is demonstrated using the examples of point source discharges into rivers and coastal waters, respectively. Furthermore, water authorities will have to make increased use of predictive modeling techniques for the implementation of the "combined approach". Key words: water pollution control, surface waters, pollutants, water framework directive, effluents, mixing zone, water quality model

Acoustic Mapping of Gas Stored in Sediments of Shallow Aquatic Systems Linked to Methane Production and Ebullition Patterns

Bubble-mediated transport is the predominant pathway of methane emissions from inland waters, which are a globally significant sources of the potent greenhouse gas to the atmosphere. High uncertainties exist in emission estimates due to high spatial and temporal variability. Acoustic methods have been applied for the spatial mapping of ebullition rates by quantification of rising gas bubbles in the water column. However, the high temporal variability of ebullition fluxes can influence estimates of mean emission rates if they are based on reduced surveys. On the other hand, echo sounding has been successfully applied to detect free gas stored in the sediment, which provide insights into the spatial variability of methane production and release. In this study, a subtropical, midsize, mesotrophic drinking water reservoir in Brazil was investigated to address the spatial and temporal variability of free gas stored in the sediment matrix. High spatial resolution maps of gas content in the sediment were estimated from echo-sounding surveys. The gas content was analyzed in relation to water depth, sediment deposition, and organic matter content (OMC) available from previous studies, to investigate its spatial variability. The analysis was further supported by measurements of potential methane production rates, porewater methane concentration, and ebullition flux. The largest gas content (above average) was found at locations with high sediment deposition, and its magnitude depended on the water depth. At shallow water depth (12 m), the gas stored in the sediment is released episodically during short events. An artificial neural network model was successfully trained to predict the gas content in the sediment as a function of water depth, OMC, and sediment thickness (R$^2$ = 0.89). Largest discrepancies were observed in the regions with steep slopes and for low areal gas content (<4 L m$^{−2}$). Although further improvements are proposed, we demonstrate the potential of echo-sounding for gas detection in the sediment, which combined with sediment and water body characteristics provides insights into the processes that regulate methane emissions from inland waters

Effects of dimensionality on the performance of hydrodynamic models for stratified lakes and reservoirs

Numerical models are an important tool for simulating temperature, hydrodynamics, and water quality in lakes and reservoirs. Existing models differ in dimensionality by considering spatial variations of simulated parameters (e.g., flow velocity and water temperature) in one (1D), two (2D) or three (3D) spatial dimensions. The different approaches are based on different levels of simplification in the description of hydrodynamic processes and result in different demands on computational power. The aim of this study is to compare three models with different dimensionalities and to analyze differences between model results in relation to model simplifications. We analyze simulations of thermal stratification, flow velocity and substance transport by density currents in a medium-sized drinking-water reservoir in the subtropical zone, using three widely used open-source models: GLM (1D), CE-QUAL-W2 (2D) and Delft3D (3D). The models were operated with identical initial and boundary conditions over a 1-year period. Their performance was assessed by comparing model results with measurements of temperature, flow velocity and turbulence. Our results show that all models were capable of simulating the seasonal changes in water temperature and stratification. Flow velocities, only available for the 2D and 3D approaches, were more challenging to reproduce, but 3D simulations showed closer agreement with observations. With increasing dimensionality, the quality of the simulations also increased in terms of error, correlation and variance. None of the models provided good agreement with observations in terms of mixed layer depth, which also affects the spreading of inflowing water as density currents and the results of water quality models that build on outputs of the hydrodynamic models

Avanços e desafios da ciência de recursos hídricos no Brasil: uma síntese comunitária do XXIII Simpósio Brasileiro de Recursos Hídricos

In this paper we synthesize the special sessions of the XXIII Brazilian Water Resources Symposium 2019 in order to understand the major advances and challenges in the water sciences in Brazil. We analyzed more than 250 papers and presentations of 16 special sessions covering topics of Climate Variability and Change, Disasters, Modeling, Large Scale Hydrology, Remote Sensing, Education, and Water Resources Management. This exercise highlighted the unique diversity of natural and human water features in Brazil, that offers a great opportunity for understanding coupled hydrological and societal systems. Most contributions were related to methods and the quantification of water phenomena, therefore, there is a clear necessity for fostering more research on phenomena comprehension. There is a vast network of co-authorship among institutions but mostly from academia and with some degree of regional fragmentation. The ABRhidro community now has the challenge to enhance its collaboration network, the culture of synthesis analysis, and to build a common agenda for water resources research. It is also time for us to be aligned with the international water science community and to use our experiences to actively contribute to the tackling of global water issues.Este artigo apresenta uma síntese das sessões especiais do XXIII Simpósio Brasileiro de Recursos Hídricos 2019, com o objetivo de compreender os principais avanços e desafios em recursos hídricos no Brasil. Foram analisados mais de 250 trabalhos e apresentações em 16 sessões especiais abrangendo temas como Variabilidade e Mudanças Climáticas, Desastres, Modelagem, Hidrologia de Grande Escala, Sensoriamento Remoto, Educação e Gestão de Recursos Hídricos. Esta avaliação destacou a diversidade única de atributos naturais e antrópicos dos recursos hídricos brasileiros, que oferece uma grande oportunidade para aprendizado sobre sistemas hidrológico e humano acoplados. A maioria das contribuições é relacionada a métodos e quantificação de fenômenos hídricos, existindo uma necessidade clara de incentivo a mais pesquisas em compreensão de fenômenos. Existe uma vasta rede de coautores, mas principalmente da academia e com certo grau de fragmentação regional. A comunidade da ABRhidro tem o desafio de aumentar a sua rede de colaboração, a cultura de análises de síntese, e construir uma agenda comum para a pesquisa em recursos hídricos. Também é o momento de alinhar esforços com a comunidade de recursos hídricos internacional, usando nossas experiências para contribuir ativamente na solução de questões relacionadas à água em nível global

Coupled 3D hydrodynamic models for submarine outfalls. Denvironmental hydraulic design and control of multiport diffusers

The book describes the hydraulic design and environmental impact prediction technologies for such installations. Focus are the hydrodynamics approached by computer models. First, a multiport diffuser design program was developed. Second, two model systems for discharge analysis, CORMIX for the near-field and intermediate-field and Delft3D for the far-field were coupled, and third a regulatory procedure is proposed to license and monitor outfall installations