THE EFFECT OF PRICE ON LONG RUN WATER SUPPLY BENEFITS AND COSTS1

ABSTRACT The long-term effects of presently used and alternatively proposed water pricing policies were studied using some tools of operations research and economics. A discrete deterministic dynamic programming model was structured and operated to determine the optimal water supply capacity expansion paths for a hypothetical residential community with a given water pricing policy. The objective of the model was the maximization of future discounted consumers'surpluses plus producer's revenues net of the long-run cost of supply. State variables were the size of system capacity in MGD and stage variables were the times of feasible capacity increase in years. Demand curves, population sizes, and growth rates for various economic sectors of the community were assumed known, as well as short-run production and capital construction costs. Several policies, including constant unit rates, decreasing or increasing block rates and summer differential rates were tested. It was concluded that price plays a major role in the short-run allocation and long-run planning and conservation of water supplies. Conservational pricing policies were advocated as means of lowering the long-run cost of water, using the water price-demand function as a planning tool. Further research in these areas was recommended.     

POST‐HARVEST RIPARIAN BUFFER RESPONSE: IMPLICATIONS FOR WOOD RECRUITMENT MODELING AND BUFFER DESIGN1

Despite the importance of riparian buffers in providing aquatic functions to forested streams, few studies have sought to capture key differences in ecological and geomorphic processes between buffered sites and forested conditions. This study examines post‐harvest buffer conditions from 20 randomly selected harvest sites within a managed tree farm in the Cascade Mountains of western Washington. Post‐harvest wind derived treefall rates in buffers up to three years post‐harvest averaged 268 trees/km/year, 26 times greater than competition‐induced mortality rate estimates. Treefall rates and stem breakage were strongly tied to tree species and relatively unaffected by stream direction. Observed treefall direction is strongly biased toward the channel, irrespective of channel or buffer orientation. Fall direction bias can deliver significantly more wood recruitment relative to randomly directed treefall, suggesting that models that utilize the random fall assumption will significantly underpredict recruitment. A simple estimate of post‐harvest wood recruitment from buffers can be obtained from species specific treefall and breakage rates, combined with bias corrected recruitment probability as a function of source distance from the channel. Post‐harvest wind effects may reduce the standing density of trees enough to significantly reduce or eliminate competition mortality and thus indirectly alter bank erosion rates, resulting in substantially different wood recruitment dynamics from buffers as compared to unmanaged forests.     

BUFFER STRIPS TO PROTECT WATER SUPPLY RESERVOIRS: A MODEL AND RECOMMENDATIONS1

ABSTRACT: Buffer strips are undisturbed, naturally vegetated zones around water supply reservoirs and their tributaries that are a recognized and integral aspect of watershed management. These strips can be very effective in protecting the quality of public potable water supply reservoirs by removing sediment and associated pollutants, reducing bank erosion, and displacing activities from the water's edge that represent potential sources of nonpoint source pollutant generation. As part of a comprehensive watershed management protect for the State of New Jersey, a parameter-based buffer strip model was developed for application to all watersheds above water supply intakes or reservoirs. Input requirements for the model include a combination of slope, width, and time of travel. The application of the model to a watershed in New Jersey with a recommended buffer strip width that ranges from 50 to 300 feet, depending upon a number of assumptions, results in from 6 to 13 percent of the watershed above the reservoir being occupied by the buffer.     

INVESTMENT IN THE COPPER INDUSTRY: NEEDS AND POLICIES

Investment required in the copper industries of the market economies over the period 1977-90 is estimated. The estimation methodology involves projection of copper consumption in the developed market economies, developing economies, and centrally planned economies. For the market group as a whole, consumption projections lead to required incremental capacity estimates and finally to required investment figures. (Pollution abatement costs and exploration requirements are also included). The sensitivity of investment requirements to major determining factors is investigated. Finally, the broader question of appropriate intergovernmental policies to influence the geographic allocation of minerals investment - including copper investment - is considered.     

COPPER, TECHNOLOGY AND DEPENDENCE IN ZAIRE: TOWARDS THE DEMYSTIFICATION OF THE NEW WHITE MAGIC

In the past, the dependence of developing country producers of minerals was thought to be related to lack of capital and lack of personnel. At present, this dependence is maintained by the “new white magic” of technology. Examining the concrete case of copper in Zaire, this article deals with three broad aspects of technological dependence: in the provision of technical personnel for the mining enterprises, in the processing of minerals, and in marketing. In each case, it can be shown that the potential independence of Zaire is considerably greater than what has actually been achieved to date. Moreover, a major barrier to the achievement of more effective national control over the copper industry is the misperception on the part of Zaire of certain key aspects of the industry. A clearer view of the reality of the copper sector would show that national control can in fact be realized. Autrefois on pensait que la dépendence des pays en développement producteurs de minéraux était liée au manque de capitaux et de cadres. De nos jours, cet état de dépendance est alimenté par la “nouvelle magie blanche” de la technologie. En examinant le cas concret du cuivre au Zaïre cet article présente trois grandes lignes de cette dépendance technologique en matière de personnel technique des entreprises minières, de traitement des minéraux et de leur commercialisation. Dans chaque cas, on peut démontrer que les chances d'indépendance du Zaïre sont sensiblement plus élevées qu'elles ne l'ont été jusqu‘à présent. De plus, la perception erronée qu'a le Zaïre de certains aspects clefs de son industrie constitute un obstacle majeur à la réalisaton d'un contrôle national plus efficace de l'industrie du cuivre. Une vue plus claire des réalités du secteur du cuivre démontrerait qu'un contrôle national peut effectivement être mis en place. En el pasado se pensaba que la dependencia de los países en desarrollo productores de minerales estaba relacionado a la falta de capital y personal capacitado. Al presente esta dependencia se mantiene gracias a la “magia blanca de la tecnología.” Al examinar el caso concreto del cobre en Zaire, este artículo trata tres aspectos amplios de dependencia tecnológica: en el personal técnico de las compañías mineras, en el proceso de minerales y en el mercadéo. En cada caso se puede demostrar que el potencial para la independencia tecnológica de Zaire es considerablemente mayor que la que se ha alcanzado al presente. Sin embargo, la mayor barrera para obtener un control nacional más efectivo de la industria de cobre es la falsa percepción de parte de Zaire sobre ciertos aspectos claves de la industria. Una visión más clara de la realidad del sector cuprífero podría mostrar que su control nacional es posible de conseguir.     

ARSENIC IN THE SHALLOW GROUND WATERS OF CONTERMINOUS UNITED STATES: ASSESSMENT,HEALTH RISKS,AND COSTS FOR MCL COMPLIANCE1

A methodology consisting of ordinal logistic regression (OLR) is used to predict the probability of occurrence of arsenic concentrations in different threshold limits in shallow ground waters of the conterminous United States (CONUS) subject to a set of influencing variables. The analysis considered a number of maximum contaminant level (MCL) options as threshold values to estimate the probabilities of occurrence of arsenic in ranges defined by a given MCL of 3, 5, 10, 20, and 50 μg/l and a detection limit of 1 μg/l. The fit between the observed and predicted probability of occurrence was around 83 percent for all MCL options. The estimated probabilities were used to estimate the median background concentration of arsenic in the CONUS. The shallow ground water of the western United States is more vulnerable than the eastern United States. Arizona, Utah, Nevada, and California in particular are hotspots for arsenic contamination. The risk assessment showed that counties in southern California, Arizona, Florida, and Washington and a few others scattered throughout the CONUS face a high risk from arsenic exposure through untreated ground water consumption. A simple cost effectiveness analysis was performed to understand the household costs for MCL compliance in using arsenic contaminated ground water. The results showed that the current MCL of 10 μg/l is a good compromise based on existing treatment technologies.