Visualising a Stochastic Model of Californian Water Resources Using Sankey Diagrams

This paper describes a novel approach to the analysis of supply and demand of water in California. A stochastic model is developed to assess the future supply of and demand for water resources in California. The results are presented in the form of a Sankey diagram where present and stochastically-varying future fluxes of water in California and its sub-regions are traced from source to services by mapping the various transformations of water from when it is first made available for use, through its treatment, recycling and reuse, to its eventual loss in a variety of sinks. This helps to highlight the connections of water with energy and land resources, including the amount of energy used to pump and treat water, the amount of water used for energy production, and the land resources that create a water demand to produce crops for food. By mapping water in this way, policy-makers can more easily understand the competing uses of water, through the identification of the services it delivers (e.g. sanitation, food production, landscaping), the potential opportunities for improving the management of the resource and the connections with other resources which are often overlooked in a traditional sector-based management strategy. This paper focuses on a Sankey diagram for water, but the ultimate aim is the visualisation of linked resource futures through inter-connected Sankey diagrams for energy, land and water, tracking changes from the basic resources for all three, their transformations, and the final services they provide.     

BOUNDARY ELEMENT ANALYSIS OF VISCOUS CHANNEL FLOW

The boundary element method (BEM) is used to investigate laminar viscous flows in internal channels. A direct iterative scheme is used to cope with the nonlinear character of the integral equations. To achieve convergence, an underrelaxation technique is employed at relatively high Reynolds numbers. Numerical examples of Poisseuille and backward-facing step flow problems are considered. It is found that BEM gives accurate solutions up to a certain Reynolds number for each case.     

Study of Staphylococcus aureus collected at slaughter from dairy cows with chronic mastitis

Staphylococcus aureus is one of the most important pathogens associated with bovine mastitis. Recent studies have shown that Staph. aureus strains may differ in virulence, and in their ability to disseminate across commercial dairy herds. The goal of this study was to determine whether Staph. aureus isolates differed in their ability to colonize mammary tissue, and whether such differences could be related to molecular characteristics. Quarter milk and mammary tissues of 22 cows from two dairy herds, were collected at slaughter and bacteriological analysis was performed. All Staph. aureus isolates were characterized by Pulsed Field Gel Electrophoresis (PFGE) and microarray. Overall 45 mammary quarters were infected and 20 Staph. aureus isolates were identified. The bacteria were mostly recovered from both milk and tissue of the same quarter in significantly higher numbers from herd A cows compared with herd B. Molecular characterization of the isolates showed distinct PFGE profiles for isolates from each herd. Differences in virulence factors between herds A and B isolates were evidenced The genes for enterotoxin D, J and R were present in herd A, those for G, I, N, M, O and U were shown in herd B, whilst both components of the leukocidin lukD/E genes were only carried by herd A isolates. Furthermore, all herd A isolates showed β-haemolysin activity, which was absent in all but one isolate from herd B. Therefore our data indicate that Staph. aureus isolates showing differences in their ability to disseminate and colonize across quarters, also have significantly different virulence characteristics.     

Finite element modelling of interfacial failure in model carbon fibre-epoxy composites

Finite element analysis has been used to model a single unsized carbon fibre embedded in an epoxy matrix subjected to tensile loading. The predicted fibre strain distribution is compared with experimental data, obtained using the technique of laser Raman spectroscopy, for a number of incremental applied strain levels. Good correlation is obtained on the assumption that the prevailing mode of interfacial failure in the composite involves a conical matrix crack initiating at the fibre end. The geometry of the matrix crack is estimated on the assumption that the crack propagates in a self-similar manner.     

Evaluation of Alternative Media for Pebble Matrix Filtration Using Clay Balls and Recycled Crushed Glass

Protecting slow sand filters (SSFs) from high-turbidity waters by pretreatment using pebble matrix filtration (PMF) has previously been studied in the laboratory at University College London, followed by pilot field trials in Papua New Guinea and Serbia. The first full-scale PMF plant was completed at a water-treatment plant in Sri Lanka in 2008, and during its construction, problems were encountered in sourcing the required size of pebbles and sand as filter media. Because sourcing of uniform-sized pebbles may be problematic in many countries, the performance of alternative media has been investigated for the sustainability of the PMF system. Hand-formed clay balls made at a 100-year-old brick factory in the United Kingdom appear to have satisfied the role of pebbles, and a laboratory filter column was operated by using these clay balls together with recycled crushed glass as an alternative to sand media in the PMF. Results showed that in countries where uniform-sized pebbles are difficult to obtain, clay balls are an effective and feasible alternative to natural pebbles. Also, recycled crushed glass performed as well as or better than silica sand as an alternative fine media in the clarification process, although cleaning by drainage was more effective with sand media. In the tested filtration velocity range of (0.72–1.33)??m/h and inlet turbidity range of (78–589) NTU, both sand and glass produced above 95% removal efficiencies. The head loss development during clogging was about 30% higher in sand than in glass media.     

Including transformation products into the risk assessment for chemicals: the case of nonylphenol ethoxylate usage in Switzerland

A method for applying the risk assessment approach using ratios of predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs) to mixtures of parent compounds and their environmental transformation products is presented. Nonylphenol ethoxylates (NPnEOs) and a selection of their most relevant transformation products are investigated as a case study illustrating the method. The PEC values of NPnEO and its transformation products are calculated with a regional multimedia fate model including the transformation kinetics of the NPnEO degradation cascade. PNEC values are derived from a selection of toxicity data on NPnEO and its transformation products. The toxicity of the emerging mixture of NPnEO and its transformation products is then estimated under the assumption of concentration addition (similar mode of action). On this basis, PEC-to-PNEC ratios for the aquatic environment and the sediment are calculated for the individual components of the mixture and the mixture itself. For this purpose, average release rates of NPnEO and its transformation products from Swiss sewage treatment plants were used. While the PEC values of the individual components do not exceed the corresponding PNEC values, the risk quotient of the mixture in water is greater than 1. In sediment, the mixture does not exceed a risk quotient of 1. A combination of sensitivity and scenario analyses is employed to identify the upper and lower bounds of the results.     

The impact of climate change on reservoir water quality and water treatment plant operations: a UK case study

A simplified climate change impact assessment tool (SCIAT) has been developed to address the specific needs of the water industry and provides a tool to translate climate change projections into ‘real world’ impacts. Its application is demonstrated in this study to assess the impacts of climate change on the reservoir water quality and water treatment plant (WTP) operations at Grafham Water in the east of England. The primary aim is to provide WTP operators with knowledge of the potential impacts and associated probabilities of occurrence of climate change, enabling them to make informed, risk‐based adaptation and planning decisions. Using a series of coupled hydrological and water‐quality models, it is likely that there will be a decline in average reservoir water quality. Climate change will also have an impact on WTP operations, but these will be manageable within the current operational parameters.