Underground coal mining operations induce ground movements, which may impact overlying hydrogeologic systems. Potential impacts mainly include changes in the hydraulic conductivity of overlying strata, decreasing of the hydraulic head and changes in water flow. The present research quantifies potential hydrogeologic impacts caused by underground mining through modeling of pre- and post-mining hydrogeologic systems. Three-dimensional conceptual hydrogeologic models were constructed with the Processing Modflow for Windows software package (PMWiN). The models are based on an actual case study, but were simplified in terms of geometry and material properties. Water flow was simulated under changing hydrogeologic properties. A number of scenarios were investigated including models with horizontal or inclined topography, featuring an aquifer overlying two longwall panels. The hydrogeologic properties of the models were estimated based on empirical relationships between the post-mining hydraulic conductivity and strain in the overburden. The strain regime in the overburden was estimated using the Surface Deformation Prediction System (SDPS) package, which allows calculation of surface deformations due to underground coal mining. The research focuses on changes in hydraulic heads; results indicate that hydraulic heads may decrease over undermined areas and may rebound as mining ceases. Water infiltration may occur from higher located overburden formations to lower formations due to mining induced changes in hydrogeologic properties.

Two-phase flow in small tubes and channels is becoming a common phenomenon in industrial processes. However, the study of two-phase flow regimes in small tubes is still at its infancy. The previous studies are reviewed and discussed in the literature section. The problems and inconsistencies encountered in the earlier studies are presented and discussed. The experimental facility is introduced in the chapters that follow. They include a section on the design of the experimental system and the test sections, the selection of the experimental parameters and the introduction of the purposely-developed programs to control the experiments and collect and process the data. The methodology of the calibration and the uncertainty analysis, the problems encountered and their solutions and the single-phase validation experiments are also described. In this project we studied the effect of tube diameter and fluid flow parameters on flow patterns in small tubes using R134a as the working fluid. The tested tube diameters were 1.10, 2.01, 2.88 and 4.26 mm; the fluid pressures were 6, 10 and 14 bar; the liquid and gas superficial velocities covered a range of 0.04-5.0 m/s and 0.01-10.0 m/s respectively. The observed flow patterns included bubbly, dispersed bubble, confined bubble, slug, chum, annular and mist flow. Twelve integrated flow maps are sketched in this report. The obtained results were compared with earlier experiments by other workers and with existing models, with obvious differences in the prediction of the transition boundaries. A set of new models and correlations were developed, based on the new data for boiling R134a presented in this thesis, to predict the effect of tube diameter and fluid properties on the transition boundaries. Some also agreed with the limited data available from earlier studies for adiabatic air-water flow in small to normal size tubes.

Water flow is an important abiotic factor for corals and other cnidarians. This study shows how water flow influences bleaching in Palythoa caribaeorum. Colonies were exposed to flow (low = 3 cm s-1, high = 15 cm s-1) in two temperature regimes (low: 26.5°C, which is within natural variability on the reef where specimens were collected; high: 33.5°C, which is 3.5°C above usual summer temperature) in a unidirectional flume for 48 hours. Two sizes (small = 2.3 ± 0.2 cm, large = 7.3 ± 0.4 cm in diameter) were tested in six repeats per flow regime. Bleaching was determined by zooxanthellae count using a hemocytometer and by chlorophyll a concentration using fluorometry. Results suggest that onset of bleaching is rapid (within 48 hours) in high temperature. The low temperature did not cause significant bleaching. In the high temperature treatment, P. caribaeorum consistently bleached less in high flow. Upstream sides of large colonies bleached less than the downstream sides in high flow. In high flow, small colonies bleached less than large colonies. This suggests that enhanced diffusion of toxic oxygen species is important to mitigate bleaching and is more easily accomplished in small colonies, which may thus have an advantage during bleaching events, as has been observed in the literature.

Various adaptation and mitigation strategies have been explored to cope with changes in the climate. Estimating these strategies impacts on the local economy is one of the growing and pressing issues for the management of natural resources. This thesis consists of three parts and aims to contribute to regional economic studies by analyzing: (1) the economic impact of solar energy facilities, (2) the level of virtual water flow and the effectiveness of scenarios to mitigate water resource shortage, and (3) the impact of climate change on agriculture through a Ricardian approach weighted by stream flow connectivity. As an increasingly adopted renewable energy resource, solar power has a high potential for carbon emission reduction and economic development. In the first essay the impacts on jobs, income, and economic output of a new solar power plant are calculated in an input-output framework. The contribution is twofold. First, we compare the multipliers generated by the construction and operation/maintenance of a plant located in California with those that would pertain had it been built in Arizona. Second, we point out the differences in the results obtained with the popular IMPLAN software from those obtained with the solar photovoltaic model of JEDI. The second essay focuses on water use in Arizona. As much as 73% of the state's scarce water is used by a single sector: crop production. Because 79% of Arizona's crop production is consumed outside the state, this means that, 67% of the water available in the state is being exported to the rest of the country and abroad. This should be of major concern for a state expected to see its population grow and its climate get drier. Using input-output techniques we explore three scenarios aimed at saving 19% of the water available. This figure is based on the results of the first of the scenarios that explores how much can be saved through improving the efficiency of the current irrigation system. The second scenario shows that equivalent water savings could be reached by a twenty-seven-fold increase in the price of water. The third scenario shows that a 19.5% reduction in crop exports could conserve an equal amount of water. The model results suggest that the least costly solution is a more efficient irrigation system, while export reduction is the second best choice. The third and final essay offers an extension of the well-known Ricardian model of agrarian economic rent. In spite of its popularity among studies of the impact of climate change on agriculture, there has been few attempts to examine the role of interregional spillovers in this framework. We remedy this gap by focusing on the spatial externalities of surface water flow used for irrigation purposes and demonstrate that farmland value—the usual dependent variable used in the Ricardian framework—is a function of the climate variables experienced locally and in upstream locations. This novel approach is tested empirically on a spatial panel model estimated across the counties of the Southwest USA for every five-year period from 1997 to 2012. This region is one of the driest in the country, hence its agriculture relies heavily on irrigation with the preponderance of the sources being surface water transported over long distances. The results highlight the significant role of irrigation spillovers and indicate that the actual impact of climate change on agriculture and subsequent adaptation policies can no longer overlook the streamflow network.

One of the most influential disturbances for stream fish assemblages is large-scale declines in flow caused by periods of drought. Although stream characteristics are known to influence the response of stream fishes to drought, we asked if ecological traits of stream fishes determine, in part, their population level response to drought. To test for ecological trait-based responses to drought in a stream fish assemblage, we quantified species abundances over a period of 5 years that represented a wet to dry period. We sampled stream fishes in Yellow Creek, Wyoming, USA, a high elevation stream dependent on snow-storage for most of its flow. There were five regularly occurring species in the study site: redside shiner (Richardsonius balteatus), northern leatherside chub (Lepidomeda copei), mottled sculpin (Cottus bairdi), speckled dace (Rhinichthys osculus), and mountain sucker (Catostomus platyrhynchus). We used size class, species, and drought measures as predictors of abundance. Mean Palmer drought severity index over the growing season from the previous year (one year lag) provided the best predictor of stream fish abundances. Four of five species showed strong declines in abundance in response to drought conditions (mountain sucker abundance was not affected), but ecological traits of species were not good predictors of the magnitude of response to drought. Northern leatherside chub are most vulnerable to local extirpation during times of severe drought. Overall, juveniles showed a greater decline in abundance than adults in response to drought. Climate models predict that mountain streams will experience changes in flow regime, which may exacerbate effects of drought. Low flow refuge habitat may need to be incorporated into stream restoration designs to help increase recolonization in streams, especially for stream fishes that are most vulnerable to local extirpation and that have low recolonization rates.

The diploma thesis focuses on the design of the flow adjustment, taking into account the flood protection and revitalization of the Leskava river. The first step is creating a computing model of a river section using the programme HEC_RAS. Based on results and the course, there is an adjustment proposed and the prevention of infiltrations in the intravilan.

Der Bericht beschreibt die Arbeiten zur CFD-Modellentwicklung zur Beschreibung des Fasertransportes in einer Wasserströmung, die im Unterauftrag der Hochschule Zittau/Görlitz erfolgten. Während die experimentellen Arbeiten zu dieser Thematik in Zittau durchgeführt wurden, lag der Schwerpunkt der theoretischen Arbeiten in Rossendorf. Im Arbeitspunkt EZ 1 des Projektantrages ist die Erweiterung der Einzeleffektuntersuchungen vorgesehen. Die entsprechenden Modellansätze zum Partikeltransport sind im Kapitel 3.1. beschrieben. Die Modellanpassung und Validierung ist in 3.2 und 3.3 dargestellt. Der Fasertransport in einer Wasserströmung wird durch Jet-Phänomene bestimmt. Untersuchungen dazu sind im EZ3.1 des Projektantrages: 3D-Phänomene infolge Blasenmitriss vorgesehen und die Modellansätze und der Vergleich zu Experimenten in den Kapiteln 4.1 bis 4.3 dargestellt. Des Weiteren wird der Einfluss auf den Ausgleich der Temperatur für den Fall untersucht, dass der Jet kälter als die Wasservorlage im Tank ist. Dieser Abschnitt entspricht damit der EZ3.2 des Antrages: 3D-Phänomene infolge Temperaturdifferenzen. Im Kapitel 4.4 wird auf die Strömungsvorgänge in der Zittauer Strömungswanne eingegangen und damit der Punkt EZ4 des Antrages: Integraluntersuchungen bearbeitet. Kapitel 5 beschreibt die Entwicklung eines Sieb-Modells, das die Faser-Kompaktierung berücksichtigt und auf der Darcy-Gleichung basiert. Die Modellparameter werden an Experimenten in Zittau justiert. Diese Experimente wurden für verschiedene Materialien durchgeführt und mit deren Hilfe ein Koeffizientenkatalog erstellt. Das Modell wurde in den CFD-Code CFX implementiert und anhand einiger Anwendungsbeispiele demonstriert.

Many coastal ecosystems around the world are dominated by submerged aquatic vegetation (SAV) habitats. These SAV habitats are known to provide many highly valuable ecosystem services such as habitat for commercial important species and increased water clarity. Water flow is an environmental variable which can have measurable effects on the ecosystem services provided by SAV, but is often not considered in studies assessing these services. This dissertation sought to investigate the links between SAV, primarily seagrasses, and hydrodynamics, paying special attention to the effects on sediments and fauna. Three main areas are discussed: (1) the effects of SAV on flow, (2) the effects of SAV and flow on deposition in SAV beds, and (3) the effects of SAV and flow on faunal communities in SAV beds. Seagrasses and other SAV reduce currents, attenuate waves, and dampen turbulence within their vegetative canopies, which in turn can enhance deposition and reduce the resuspension of sediment, organic matter, and passively settling larvae. The ability of SAV to retard flow may be further enhanced by increases in vegetated structure, such as shoot density, biomass, or canopy height, which can promote increased abundance and diversity of in- and epifauna within SAV beds. Ultimately, it is clear that hydrodynamics is an important factor that shapes SAV communities both physically (e.g. deposition, sediment structure, etc.) and biologically (e.g. faunal community composition, predation pressure, food availability, etc.).

Dissolved organic matter (DOM) in surface waters affect many important ecological functions. For instance, transporting metals, nutrients, carbon, affecting pH and water colour. In large parts of the Northen hemisphere, surface waters have become browner as a consequense of increasing DOM concentrations and, to some extent, iron. Therfore, altering ecological functions in waters. As such, knowing the causes and extent of the increase is of great importance. This paper used monthly data from the national Swedish monitoring program to investigate trends in DOM-concentrations in the Rickleå river, Västerbotten, Sweden. Results showed a large increase in concentrations of DOM from 1970-2019. However, the increase was most pronounced between 1970-1990, showing no trend after 2003 and indications of a decrease from 2009. DOM-quality changed as well to larger and more colored molecules during 1987-2002 and less coloured, smaller molecules after 2003. Changes in water flow could be an explanation for short-term fluctuations in DOM-concentration, but did not correlate well to increasing trends. However, a large lake at the river inlet as well as hydroelectric dams along the watershead complicates the interpretation between flow and DOM correlation. Climate change did not seem to be an important driver of long term increases in DOM. Further investigations should be carried out to test this hypothesis as well to investigate the cause for the increase.

The aim of the thesis is hydraulic computation of shallow water flow in floodplains with using 2D numerical modelling. Processing river is Dyje in the south of Moravia in location Břeclav. For model creation is necessary to know the software, accumulate input data and prepare model input parameters. Output data are process to form of maps water depths and maps water flow velocities.