Numerical simulation of water mixing and renewals in the Barcelona harbour area: the winter season

In the present paper, we use numerical simulation to investigate currents, mixing and water renewal in Barcelona harbour under typical conditions of wind forcing for the winter season. This site is of particular importance due to the interplay between touristic and commercial activities, requiring detailed and high-definition studies of water quality within the harbour. We use Large Eddy Simulation (LES) which directly resolves the anisotropic and energetic large scales of motion and parametrizes the small, dissipative, ones. Small-scale turbulence is modelled by the anisotropic Smagorinsky model (ASM) to be employed in presence of large cell anisotropy. The complexity of the harbour is modelled using a combination of curvilinear, structured, non-staggered grid and the immersed boundary method. Boundary conditions for wind and currents at the inlets of the port are obtained from in-situ measurements. Analysis of the numerical results is carried out based on both instantaneous and time-averaged velocity fields. First- and second-order statistics, such as turbulent kinetic energy and horizontal and vertical eddy viscosities, are calculated and their spatial distribution is discussed. The study shows the presence of intense current in the narrow and elongated part of the harbour together with sub-surface along-shore elongated rolling structures (with a time scale of a few hours), and they contribute to the vertical water mixing. Time-averaged velocity field reveals intense upwelling and downwelling zones along the walls of the harbour. The analysis of second-order statistics shows strong inhomogeneity of turbulent kinetic energy and horizontal and vertical eddy viscosities in the horizontal plane, with larger values in the regions characterized by stronger currents. The water renewal within the port is quantified for particular sub-domain regions, showing that the complexity of the harbour is such that certain in-harbour basins have a water renewal of over five days, including the yacht marina area. The LES solution compares favourably with available current-meter data. The LES solution is also compared with a RANS solution obtained in literature for the same site under the same forcing conditions, the comparison demonstrating a large sensitivity of properties to model resolution and frictional parametrization.     

Demography and interannual variability of salp swarms (Thalia democratica)

Swarms of the pelagic tunicate, Thalia democratica, form during spring, but the causes of the large interannual variability in the magnitude of salp swarms are unclear. Changes in asexual reproduction (buds per chain) of T. democratica populations in the coastal waters of south-east Australia (32–35°S) were observed in three austral springs (October 2008–2010). T. democratica abundance was significantly higher in 2008 (1,312 individuals m^?3) than 2009 and 2010 (210 and 92 individuals m^?3, respectively). There was a significant negative relationship (linear regression, r ² = 0.61, F _1,22 = 33.83, P < 0.001) between abundance and asexual reproduction. Similarly, relative growth rates declined with decreasing abundance. Generalised additive mixed modelling showed that T. democratica abundance was significantly positively related to preferred food >2 μm in size (P < 0.05) and negatively related to the proportion of non-salp zooplankton (P < 0.001). Salp swarm magnitude, growth, and asexual reproduction may depend on the abundance of larger phytoplankton (prymnesiophytes and diatoms) and competition with other zooplankton.     

Tax evasion and optimal environmental taxes

This paper introduces a new argument to the debate about the role of environmental taxes in modern tax systems. Some environmental taxes, particularly taxes on gasoline or electricity, are more difficult to evade than taxes on labor or income. When the tax base is shifted in a revenue-neutral manner toward these environmental taxes, the result is a net reduction in the amount of tax evasion. Using a carbon tax as a motivating example, the “tax evasion effect” is shown to sharply reduce the welfare cost of controlling emissions. A simple computable general equilibrium model suggests that the impact of considering tax evasion can be large: costs are lowered by 28% in the United States, by 89% in China, and by 97% in India. In countries with high levels of pre-existing tax evasion, a carbon tax will pay for itself through improvements in the efficiency of the tax system.     

Book reviews

Traffic Mix Model

(TRRU Research Report No. 30).

A Methodology for Estimating Recreation Traffic Flows.

August 1977, University of Edinburgh. 144 pps.

“Recreation in the Highlands and Islands”

Tourism and Recreation Research Unit, University of Edinburgh, December 1976.

Research Report No. 22, 411pp with tables and diagrame; Research Report No. 31, 145 with tables and diagrams.

Tourism and Recreation in the Chichester Area: a basis for planning

Tourism and Recreation Research Unit, Research Report No. 35, University of Edinburgh.

The Real Wealth of Nations

S. R. Eyre

Arnold, London, 1978. £7.95.

Landscape Construction

M. F. Downing

E. & F. N. Spon, London, 1977

Planning and Organizing for Social Change. Action Principles from Social Science Research.

Jack Rothman

Columbia University Press. 628 p.p.

Models and Cities and Regions

A. G. Wilson, P. H. Rees, C. M. Leigh (editors) 1977

Wiley, £12.75.

Ecology and Ekistics

C. A. Doxiadis Edited by Gerald Dix

Paul Elek, London 1977. Environmental Studies Series. 91 p.p. Paperback. £3.75.

Tackling Urban Deprivation : The Contribution of Area‐Based Management

T. Mason, K. Spencer, C. Vielba and B. Webster

Institute of Local Government Studies, University of Birmingham, Dec. 1977. 93p.p. No price stated.

Marketing Geography : with special reference to retailing

R. L. Davies

Methuen, 1976. £3.45.

“Public Participation in Planning”

Edited by W. R. D. Sewell and J. T. Coppock

J. Wiley & Sons Ltd., Chichester, 1977. 208 p.p. £9.00.

“The Individual Citizen and Public Participation”

William Hampton and Raymond Walker

Linked Research Project into Structure Planning, Interim Research Paper. 13, 1978. 24 p.p. £1.00.

A Future for Planning Science Fiction Cities

Town Planning discussion paper No. 27. Stephen Wood

U.C.L. 1977.

“The Bicycle Planning Book “

Mike Hudson (editor)

Open Books Publishing Ltd. and Friends of the Earth, 1978. Paperback, £1.95.

Residential Location and Urban Housing Markets

G. K. Ingram (1977) (ed.)

Cambridge, Mass : Ballinger Publishing Co., for the National Bureau of Economic Research.     

GC/MS analysis of polynuclear aromatic hydrocarbons in sediment samples from the Niger Delta region

Thirteen sediment samples from different locations in the Niger Delta region of Nigeria were analyzed for the presence of 16 polynuclear aromatic hydrocarbons (PAHs) via gas chromatography/mass spectrometry. The specific target compounds for this study included naphthalene, acenaphthylene, acenaphthene, flourene, phenanthrene, anthracene, flouranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]flouranthene, benzo[a]pyrene, benzo[ghi]perylene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene. Four isotopically labeled polynuclear aromatic hydrocarbons (acanaphthene-d10, phenanthrene-d10, chrysene-d12 and perylene-d12) were used for internal standardization. All 16 PAHs were found in most of the thirteen samples with concentration ranging from 0.1 microg/kg to 28 microg/kg. It was also found that the 5 and 6-ring PAHs were present in higher concentrations than all the other compounds, indicating their high resistance to microbial degradation.     

Risk communication, value judgments, and the public-policy maker relationship in a climate of public sensitivity toward animals: revisiting britain's foot and mouth crisis

This paper offers some suggestions on, and encouragement for, how to be better at risk communication in times of agricultural crisis. During the foot and mouth epizootic, the British public, having no precedent to deal with such a rapid and widespread epizootic, no existing rules or conventions, and no social or political consensus, was forced to confront the facts of a perceived "economic disease. Foot and mouth appeared as an economic disease because the major push to eradicate it was motivated exclusively by trade and economic reasons and not because of threats it posed to the lives of human beings and livestock. The British public deferred responsibility to their elected officials for a speedy end to this non-life threatening viral epizootic. The latter, however, did not have a contingency plan in place to tackle such an extensive outbreak. The appeal to an existing policy, i.e., mass eradication, as the exclusive strategy of containment was a difficult pill for the public to swallow well before the end of the 226-day ordeal. Public outcry reflected (in part) serious misgivings about the lack of effective communication of risk-informed decisions between government agents and all concerned. The government's handling of the matter underestimated concerns and values about animal welfare, public trust, and the plight of farmers and rural communities. A general loss of trust by some segments of the public was exacerbated by perceived mismanagement and early fumbles by government agents.Public moral uneasiness during the crisis, while perhaps symbolic of growing discontent with an already fractured relationship with farmed animals and the state of animal farming today, arguably, also reflected deep disappointment in government agents to recognize inherently and conditionally normative assumptions in their argument as well as recognize their narrow conception of risk. Furthermore, broader stakeholder participation was clearly missing from the outset, especially with respect to the issue of vaccination. A greater appreciation for two-way risk communication is suggested for science-based public policy in agriculture, followed by suggestions on how to be more vigilant in the future.     

LIFAC ash--strategies for management

LIFAC is a more recent addition to flue gas desulphurization methods for reducing sulphur emissions during coal combustion for the production of electricity. Ashes from the combustion of a low-sulphur lignite coal using LIFAC technology were used to evaluate different ash management strategies. The ashes, as produced and after treatment by the CERCHAR hydration process, were examined for their disposal characteristics and their utilization potential in concrete. They were also evaluated as underground disposal material using the AWDS process.     

Fear,victimization, and stress among urban public school teachers

Data from the National Institute of Education's Safe School Study Report suggested that teachers in American urban public schools are emotionally and physically victimized and that the result is heightened level of stress associated with teaching. This study, which is part of larger, longitudinal project, explores the linkages between reported experiences of victimization by 291 urban public school teachers and task-specific stressors in the performance of the teaching role. The level of reported stress and nature and degree of victimization differ by the grade level taught and the race of the teacher. Generally, minority teachers (black and brown) are less likely to report being stressed or victimized than are white teachers, while elementary school teachers report their work to be most stressful. There is no evidence of a specific causal ordering between fear of victimization and teacher stress. Rather, each may feed upon and facilitate the other.     

Choosing a Management Strategy: Two Structured Decision-Making Methods for Evaluating the Predictions of Stochastic Simulation Models

We describe two structured decision-making methods—one using a hierarchy of goals and a second using ranking on the sum of weighted criteria—that may be useful for many practical conservation problems, particularly when advisory groups evaluate the output of simulation models. We illustrate both methods by applying them to the problem of choosing a management strategy to address the "mobbing" problem in endangered Hawaiian monk seals. Both methods require estimates of the probabilities of various outcomes, such as a population size of more than 400 seals after 20 years under a specific management regime. We used a simulation model of a small monk seal population to generate these probabilities. Both methods provide an explicit, well-documented, and reproducible decision process that helps justify the decision. Furthermore, they are easy for those untrained in decision analysis to understand and use, they focus discussion on management objectives, they facilitate an examination of trade-offs in the light of multiple and sometimes conflicting objectives, they are suitable for use in workshops, and, at least in our example, they lead to management recommendations that are not highly sensitive to minor changes in probability estimates or other factors.