Monitoring and modelling walking track impacts in the Tasmanian Wilderness World Heritage Area, Australia

A program has been developed for monitoring the condition of unimproved walking tracks on a 1000-km track system in Western Tasmania, and it has been used as the basis of an eight-year study of track-impact development. The monitoring technique involves measuring track depth and two track-width indicators at permanently marked and widely dispersed sites, each site comprising ten transects located at 2-m intervals. Sites have been 'typed' on the basis of track slope, drainage and substrate characteristics, and the typing scheme has been tested and refined by assessing the relationship between type-usage groups and observed impacts. Analysis reveals that track depth and rates of erosion are strongly influenced by track type and to a lesser extent by usage, while track width is influenced mainly by usage and track bogginess. The time-invariant variable 'usage gradient' was introduced to compensate for the fact that usage levels on most walking tracks in Western Tasmania have varied over time. Data derived from multiple inspections at 2-3 year intervals since 1994 from over 250 sites have been used to derive impact/time curves for different type-'usage gradient' groups. Each of the impact variables can be approximated by the formula m = alphatBeta, where m is the expected value of the impact variable, t is chronological time, and alpha and Beta are constants characteristic of the impact variable and type-'usage gradient' group in question. The typing scheme and impact-development model have the potential to be used for systematically describing and predicting impacts over extensive systems of 'typed' tracks. The implications of these findings for the ongoing monitoring, sitting and management of walking tracks are discussed.     

Relative merits of polystyrene foam and paper in hot drink cups: Implications for packaging

An analysis of the overall relative merits of the use of uncoated paper vs molded polystyrene bead foam in single-use 8-oz cups is described here as a manageable example of the use of paper vs plastics in packaging. In raw material requirements the paper cup required about 2.5 times its finished weight of raw wood and about the same hydrocarbon fueling requirement as is needed for the polystyrene foam cup. To process the raw materials about six times as much steam, 13 times as much electric power, and twice as much cooling water are consumed to produce the paper cup as compared to the polystyrene foam cup. Emission rates to air are similar and to water are generally higher for the paper cup. Virtually all primary use factors favor polystyrene foam over paper. Once used both cup types may be recycled. Landfill disposal of the two items under dry conditions will occupy similar landfill volumes after compaction and will confer similarly slow to nonexistent decomposition to either option. Under wet conditions polystyrene foam will not readily degrade, but may help other materials to do so. Paper under wet conditions will biodegrade to produce methane, a significant greenhouse gas, biochemical oxygen demand to any leachate, and instability to the land surface during the process. Both materials can be incinerated cleanly in a municipal waste stream with the option of energy recovery, to yield an ash volume of 2%–5% of the incoming waste volume. Overall this analysis would suggest that polystyrene foam, with an extension to plastics in general, should be given more evenhanded consideration relative to paper in packaging applications than is currently the case.     

THE EFFECT OF SOME BASIC STATISTICAL AND BIOLOGICAL PRINCIPLES ON WATER POLLUTION CONTROL1

ABSTRACT: The hypothesis of this paper is that the frequently used regulatory practice which employs point estimates in water pollution control objectives, in combination with monitoring at infrequent intervals, is an inadequate scientific procedure for the measurement and control of pollution. The first part of this paper outlines the relevant sampling theory which applies to the measurement of effluent from industrial plants and describes the possible errors in sampling practice which currently affect the interpretation and enforcement of environmental standards. In the second part of the paper, the authors describe briefly the environmental significance of biological damage functions. In the final part of the paper, the authors recommend that existing pollution control regulations be restructured to be more efficient and effective in the protection of both corporate and social interests. By adopting two different approaches to regulation depending upon the nature of the appropriate damage functions and critical fish species, it is possible to reduce significantly the waste of resources.     

THE ECONOMIC EFFECTS OF CHANGES IN WATER USE IN THE TUCSON BASIN,ARIZONA1

ABSTRACT: The ground water in the Tucson basin is being drawn faster than it is replenished by nature. The water table is falling, giving rise to several conflicts between water users in the basin. At present, several lawsuits are in progress, including an action by the Papago Tribe against some of the major water users in the basin. Largely because of these difficulties, the State Legislature has established a commission to make proposals for the reform of Arizona's ground water law. The pattern of water use in the basin will undoubtedly be changed by the outcome of the present litigation and the coming reform of Arizona's ground water law. This paper describes how water use in the basin might be affected by changes in the availability of water and gives an account of the effects that these changes in water use could have on the region's economy. The paper concludes that the water problems of the Tucson basin will have little effect on the region at large and that these problems are simply a matter for the Indians and the other water users in the basin to sort out amongst themselves.     

A RETROSPECTIVE BENEFIT-COST ANALYSIS OF WATER RESOURCE PROJECTS IN THE CUMBERLAND RIVER BASIN1

ABSTRACT: A retrospective benefit-cost analysis of major water resources projects in the Cumberland River basin was conducted. The U.S. Army Corps of Engineers' projects selected were Dale Hollow, Wolf Creek, Center Hill, and J. Percy Priest Reservoirs. The ex-post performance of the evaluated reservoirs were compared to the ex-ante estimates. Benefits and costs for each project were deflated to their base year and respective average annual values for each of these components were calculated. An ex-post benefit-cost ratio was determined for each project, as well as the combined system. The benefit-cost ratio for each project surpassed unity. The actual ratio as compared to the ex-ante estimate for each project is as follows: Dale Hollow, 1.24 to 1.46; Wolf Creek, 1.40 to 1.53; Center Hill, 1.17 to 2.02; and J. Percy Priest, 1.45 to 1.6. The internal rate of return was also determined for each project. The results obtained for each project are tabulated and discussed with consideration given to factors effecting the economic evaluation of the projects.     

ASSESSING SOLAR PHOTOVOLTAIC ENERGY SYSTEMS FOR CROP IRRIGATION1

ABSTRACT: An economic analysis of the profitability of adopting solar photovoltaic energy systems for crop irrigation is undertaken. The economic, technological, and political uncertainties surrounding adoption are discussed with reference to their impact on anticipated profitability. On the assumption that the costs of producing photovoltaic modules follows a learning curve characteristic of other inventions, solar systems are likely to be viable for irrigation in some states by mid to late 1980s. A field test in Nebraska is described.     

REVIEW OF LAKE RESTORATION PROCEDURES1

ABSTRACT Relevant information on the restoration of lakes is presented. The restoration procedures considered are applicable to the water, the bottom sediments, and aquatic plant improvement. A summary of thirteen (13) suggested methods of restoration are reviewed.     

Uptake rates of thorium progeny in a semiarid environment

The release rates and transformation processes that influence the mobility, biological uptake, and transfer of radionuclides are essential to the assessment of the health effects in the food chain and ecosystem. This study examined concentrations of 222Th in both soil and vegetation at a closed military training site, Kirtland Air Force Base (KAFB), New Mexico. Brazilian sludge was intentionally introduced into the topsoil in the early 1960s to simulate nuclear weapon accidents. Soil (60) and vegetation (120) samples were collected from 1996 to 2000 and analyzed for radionuclides and progeny. High-resolution gamma-ray spectroscopy was used to determine radionuclide activities. The results indicate that the thorium progeny were the predominant contaminant in soil and vegetation. Concentration ratios (CRs) were calculated based on actinium levels.