Tracer and Timescale Methods for Passive and Reactive Transport in Fluid Flows

Geophysical, environmental, and urban fluid flows (i.e., flows developing in oceans, seas, estuaries, rivers, aquifers, reservoirs, etc.) exhibit a wide range of reactive and transport processes. Therefore, identifying key phenomena, understanding their relative importance, and establishing causal relationships between them is no trivial task. Analysis of primitive variables (e.g., velocity components, pressure, temperature, concentration) is not always conducive to the most fruitful interpretations. Examining auxiliary variables introduced for diagnostic purposes is an option worth considering. In this respect, tracer and timescale methods are proving to be very effective. Such methods can help address questions such as, "where does a fluid-born dissolved or particulate substance come from and where will it go?" or, "how fast are the transport and reaction phenomena controlling the appearance and disappearance such substances?" These issues have been dealt with since the 19th century, essentially by means of ad hoc approaches. However, over the past three decades, methods resting on solid theoretical foundations have been developed, which permit the evaluation of tracer concentrations and diagnostic timescales (age, residence/exposure time, etc.) across space and time and using numerical models and field data. This book comprises research and review articles, introducing state-of-the-art diagnostic theories and their applications to domains ranging from shallow human-made reservoirs to lakes, river networks, marine domains, and subsurface flow

Development and application of an integrated hydro-environmental model for predicting the distribution of nutrients in estuarine and coastal waters

The integrated model is finally applied to simulate the hydro-environmental processes in the Loughor Estuary to find out the contribution of different pollution sources on the receiving water nutrient concentration levels, and the influences of pollutant discharging schemes and temperature. The results show that the refined model is accurate and provides a valuable state-of-the-art novel tool for predicting improved nutrient concentration distributions in estuarine and coastal waters.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Development and application of an integrated hydro-environmental model for predicting the distribution of nutrients in estuarine and coastal waters

The integrated model is finally applied to simulate the hydro-environmental processes in the Loughor Estuary to find out the contribution of different pollution sources on the receiving water nutrient concentration levels, and the influences of pollutant discharging schemes and temperature. The results show that the refined model is accurate and provides a valuable state-of-the-art novel tool for predicting improved nutrient concentration distributions in estuarine and coastal waters

Computational study of hydro-environmental processes of Poyang Lake, China

Poyang Lake, the largest freshwater lake in China, plays a key role in regulating the hydrology, water quality and ecosystem in the middle reaches of the Yangtze River. Recent industrial development and urbanization in Jiangxi province have driven rapid increase in water consumption and deterioration of water quality, exerting pressure on water utilization in the Poyang Lake basin. In order to set up an integrated water management framework for the protection of Poyang Lake’s ecosystem and surrounding communities, an accurate and representative evaluation of the hydraulic and environmental challenges is vital. In this research, a numerical model is developed and utilized to simulate the hydrodynamics and water quality of Poyang Lake and its surrounding river networks. The study couples an in-house 1-D river network hydrodynamic and mass transport model together with a 2-D MIKE hydrodynamic and water quality model. The model is validated against field-measured data from the local water authorities. The impact of the proposed downstream barrage on Poyang Lake’s hydrodynamics and water quality is then investigated. It is concluded that: the establish integrated model is capable of simulating the hydrodynamic and water-quality processes of the Poyang Lake to satisfactory degrees; and the operation of proposed barrage has large effects on the nutrients distribution and water resources availability. The findings of the study contribute to a better understanding of the fate of Poyang Lake’s pollutants and the influence of the proposed hydraulic projects on the lake’s flow and ecosystem. Many of these findings are relevant to large freshwater lakes in other developing countries and could contribute to the fields of water engineering and water management

Modeling Dispersal of UV Filters in Estuaries

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Environmental Science & Technology, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see: http://dx.doi.org/10.1021/acs.est.8b03725Lagrangian ocean analysis, where virtual parcels of water are tracked through hydrodynamic fields, provides an increasingly popular framework to predict the dispersal of water parcels carrying particles and chemicals. We conduct the first direct test of Lagrangian predictions for emerging contaminants using (1) the latitude, longitude, depth, sampling date, and concentrations of UV filters in raft cultured mussel (Mytilus galloprovincialis) of the estuary Ria de Arousa, Spain (42.5°N, 8.9°W); (2) a hydrodynamic numerical model at 300 m spatial resolution; and (3) a Lagrangian dispersion scheme to trace polluted water parcels back to pollution sources. The expected dispersal distances (mean ± SD) are 2 ± 1 km and the expected dispersal times (mean ± SD) are 6 ± 2 h. Remarkably, the probability of dispersal of UV filters from potential sources to rafts decreases 5-fold over 5 km. In addition to predicting dispersal pathways and times, this study also provides a framework for quantitative investigations of concentrations of emerging contaminants and source apportionment using turbulent diffusion. In the coastline, the ranges of predicted concentrations of the UV-filters 4-methylbenzylidene-camphor, octocrylene, and benzophenone-4 are 3.2 × 10–4 to 0.023 ng/mL, 2.3 × 10–5 to 0.009 ng/mL, and 5.6 × 10–4 to 0.013 ng/mL, respectively. At the outfalls of urban wastewater treatment plants these respective ranges increase to 8.9 × 10–4 to 0.07 ng/mL, 6.2 × 10–5 to 0.027 ng/mL, and 1.6 × 10–3 to 0.040 ng/mL.This research is supported by the Spanish State Research Agency projects CTM2014-56628-C3-2-R, CTM2014-56628-C3-3-R, CTM2017-84763-C3-2-R, CTM2017-84763-C3-3-R, and CTM2017-90890-REDT (MINECO/AEI/FEDER, EU). This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation grant number NSF-OCE170005S

A Water Quality Study of the Selangor River, Malaysia

Malaysia’s rapid economic and demographic development has put pressures on its water supplies and consequently on the quality of its river water. The Selangor River, close to the nation’s capital, is now a major source of water and there are fears that its water quality will deteriorate. The Malaysian Government in its Vision for Water 2025 states that rivers should achieve Class II as measured by Malaysia’s Water Quality Index (WQI) (Class I is cleanest). The objectives of this thesis are to investigate the effects of flow through the 10 major tidal control gates (TCGs) which regulate run-off from the oil-palm plantations into the river, and to predict the water quality for the river in 2015, 2020 and 2030. In order to achieve these objectives it was necessary to set-up, calibrate and validate a commercial one-dimensional numerical model, InfoWorks, which includes both the hydrodynamics and water quality of the river-estuary network. It was concluded that there was insufficient hydrodynamic (stage and current) and water quality data to fully calibrate and validate the InfoWorks model but it performed well when compared with measured salinity transects. The model was found to be relatively insensitive to the choice of diffusion parameters but needed a high value for the oxygen transfer velocity, 0.3 m h-1, to get reasonable values for the dissolved oxygen (DO) along the river. The effect of run-off through the TCGs was less than expected and attributed to the high oxygen transfer velocity and needs to be addressed before the model can properly represent run-off through the TCGs. The model shows the WQI of the lower reaches of the river to be Class III in both wet and dry seasons except close to the estuary where it is Class II due to tidal flushing. The dissertation identifies several deficiencies in the model; the lack of an operational ramp function at the estuary boundary, the use of a single value of the oxygen transfer velocity throughout, and the exclusion of water extraction. Land-use changes above Rantau Panjang, the upper boundary of the InfoWorks model, and water quality data were used to estimate the water quality and its uncertainties at Rantau Panjang in 2015, 2020 and 2030 due to predicted development in the upper catchment for both wet and dry seasons. InfoWorks models of water quality along the river in 2015, 2020 and 2030, which included extraction at the Batang Berjuntai barrage, predict little change in the WQ (Class II/III boundary) below the barrage during the dry season but a rapid deterioration in the wet season (down to Class III/IV by 2030) showing the importance of water extraction to the water quality of the river. Overall, because of its relative simplicity and ease of operation, InfoWorks is considered to be a useful tool for river management in Malaysia

Flow-3D CFD model of bifurcated open channel flow: setup and validation

Bifurcation is a morphological feature present in most of fluvial systems; where a river splits into two channels, each bearing a portion of the flow and sediments. Extensive theoretical studies of river bifurcations were performed to understand the nature of flow patterns at such diversions. Nevertheless, the complexity of the flow structure in the bifurcated channel has resulted in various constraints on physical experimentation, so computational modelling is required to investigate the phenomenon. The advantages of computational modelling compared with experimental research (e.g. simple variable control, reduced cost, optimize design condition etc.) are widely known. The great advancement of computer technologies and the exponential increase in power, memory storage and affordability of high-speed machines in the early 20th century led to evolution and wide application of numerical fluid flow simulations, generally referred to as Computational Fluid Dynamics {CFD). In this study, the open-channel flume with a lateral channel established by Momplot et al (2017) is modelled in Flow-3D. The original investigation on divided flow of equal widths as simulated in ANSYS Fluent and validated with velocity measurements