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1.
The paper reviews progress in the individual commodity negotiations for non-fuel minerals covered by the Integrated Programme for Commodities (IPC). Given the minimal progress to date, the author reconsiders the objectives of the IPC to gauge the extent to which they meet the needs of countries engaged in mineral production or trade. It is suggested that the major focus of the IPC be towards price stability, with less attention to other aspects of market instability and other market problems. For this reason, the IPC discussions have failed to focus on such major issues of concern in the mineral sector as measures necessary to guarantee adequate supplies of minerals over the long-term, the financing of the required investments, the expansion of production by developing countries and the securing of price levels sufficient to generate appropriate returns on capital employed. Cet article est consacré à l'étude des progrès accomplis en matière de négociations individuelles sur les produits de base concernant les minéraux non-combustibles qui figurent au Programme intégré pour les produits de base. Etant donné les résultats peu concluants qui ont été enregistrés, ‘auteur examine à nouveau les objectifs du programme pour évaluer jusqu’ à quel point ils répondent aux besoins des pays engagés dans la production ou le commerce de minéraux. Selon cet article, ‘accent principal du programme a été mis sur’ instabilité en matière de prix au détriment d'autres aspects de 'instabilité du marché et d'autres problèmes connexes. De telles discussions ont éludé les points d'intérét majeurs du secteur minier, à savoir, les mesures nécessaires à assurer à long terme des approvisionnements suffisants en minéraux, le financement des investissements nécessaires, une participation plus active des pays en développement à 'expansion de la production et le maintien de niveaux de prix susceptibles de créer des profits suffisants sur le capital investi. Este artículo revisa los progresos alcanzados en la negociación individual de minerales no combustibles cubiertos por el programs ‘Integrated Programme for Commodities’ (IPC). Dado el progreso mínimo presente, el autor reconsidera los objectivos de la IPC para apreciar el grado en que estos objectivos se ajustan a las necesidades de los países dedicados a la producción y comercio de minerales. Se sugiero que el IPC enfoca su acción a la estabilidad de precios, con menor atención a otros aspectos de inestabilidad y otros problemas de mercado. Por esta razón las discuciones de IPC no han considerado asuntos de tanta importancia en el sector minero tales como las medidas para garantizar suministros adecuados de minerales por largos plazos, el financimiento de las inversiones requeridas, la expansión de la producción por los países en desarollo y la garantía de niveles de precios suficientes para generar retornos adecuados del capital invertido.  相似文献   

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ABSTRACT: The Truckee River is a vitally important water source for eastern California and western Nevada. It runs 100 miles from Lake Tahoe to Pyramid Lake in the Nevada desert and serves urban populations in greater Reno-Sparks and agricultural users in three Nevada counties. In the 1980s and 1990s, a number of state and local groups initiated projects which, taken collectively, have accomplished much to improve watershed management on the Truckee River. However, the task of writing a management plan for the entire watershed has not yet been undertaken. Key players in state, federal and local government agencies have instead chosen to focus specific improvement efforts on more manageable, achievable goals. The projects currently underway include a new agreement on reservoir operation, restoration of high priority sub-watersheds, public education and involvement, water conservation education, and water resource planning for the major urban population centers. The approach which has been adopted on the Truckee River continues to evolve as more and more people take an interest in the river's future. The many positive projects underway on the watershed are evaluated in terms of how well they meet the definition of the ambitious water resources strategy, “integrated watershed management.”  相似文献   

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ABSTRACT: A number of studies conducted since the late 1970s have evaluated state and federal responses to drought in the United States. Each of these studies identified a number of key issues and impediments that needed to be addressed to improve the nation's ability to cope with and prepare for future episodes of drought. A content analysis of these studies was performed to identify common threads in their recommendations. The premise of this analysis was that the series of drought years that occurred between 1986 and 1992 and recurred between 1994 and 1996 increased awareness of our nation's continuing and apparent growing vulnerability to drought. This awareness has led to greater consensus among principal constituents and stakeholders, and also a greater sense of urgency to implement actions now to lessen vulnerability. The results of this analysis revealed that several themes recur: create an integrated national drought policy and plan; develop an integrated national climate monitoring (drought watch) system; incorporate drought in FEMA's National Mitigation Strategy; conduct post-drought audits of response efforts; establish regional drought forums; and encourage development of state drought mitigation plans.  相似文献   

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In 1988, the Florida Institute of Phosphate Research (FIPR) funded project to develop an advanced hydrologic model for shallow water table systems. The FIPR hydrologic model (FHM) was developed to provide an improved predictive capability of the interactions of surface water and ground water using its component models, HSPF and MODFLOW. The Integrated Surface and Ground Water (ISGW) model was developed from an early version of FHM and the two models were developed relatively independently in the late 1990s. Hydrologic processes including precipitation, interception, evapotranspiration, runoff, recharge, streamflow, and base flow are explicitly accounted for in both models. Considerable review of FHM and ISGW and their applications occurred through a series of projects. One model evolved, known as the Integrated Hydrological Model IHM. This model more appropriately describes hydrologic processes, including evapotranspiration fluxes within small distributed land‐based discretization. There is a significant departure of many IHM algorithms from FHM and ISGW, especially for soil water and evapotranspiration (ET). In this paper, the ET concepts in FHM, ISGW, and IHM will be presented. The paper also identifies the advantages and data costs of the improved methods. In FHM and IHM, ground water ET algorithms of the MODFLOW ET package replace those of HSPF (ISGW used a different model for ground water ET). However, IHM builds on an improved understanding and characterization of ET partitioning between surface storages, vadose zone storage, and saturated ground water storage. The IHM considers evaporative flux from surface sources, proximity of the water table to land surface, relative moisture condition of the unsaturated zone, thickness of the capillary zone, thickness of the root zone, and relative plant cover density. The improvements provide a smooth transition to satisfy ET demand between the vadose zone and deeper saturated ground water. While the IHM approach provides a more sound representation of the actual soil profile than FHM, and has shown promise at reproducing soil moisture and water table fluctuations as well as field measured ET rates, more rigorous testing is necessary to understand the robustness and/or limitations of this methodology.  相似文献   

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ABSTRACT: Nutrient data from all available sources for the lower Mississippi River were examined for potential differences among sampling agencies and geographic locations for the period between 1960 and 1998. Monthly means grouped by parameter, sampling location and agency, were calculated and compared as paired sets, excluding those months where data were not available for both sets. Some significant differences were found between various agencies collecting nutrient data on the river, as well as between various stretches of river, especially in the case of phosphorus nutrient data. Results were used to synthesize data sets from which a history of nutrient loading in the Mississippi River was determined. General trends in nitrate+nitrite, total Kjeldahl nitrogen, orthophosphate, total phosphorus and silica loads, as well as changes in nutrient proportions and the specific limiting nutrient (by month) are reported. This study provides a useful summary of contemporary and historical nutrient data that may assist in the evaluation of Mississippi River water quality and its potential effect on the Gulf of Mexico.  相似文献   

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Common carp (Cyprinus carpio) collected from four sites in the Red River of the North in 1994 were analyzed for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), nickel (Ni), selenium (So), and zinc (Zn). Concentrations differed among liver, muscle, and whole body. Generally, trace element concentrations were the greatest in livers while concentrations in whole bodies were greater than those in muscle for Cd, Cu, Ni, Pb, and Zn, and concentrations in muscle were similar to whole body for As and Se. Concentrations of Cr were lower in liver than either muscle or whole body. Correlations between liver and whole body concentrations were stronger than those between liver and muscle concentrations, but the strongest correlations were between muscle and whole body concentrations. Examination of tissue concentrations by collection sites suggested that, for a general survey, the whole body may be the most effective matrix to analyze.  相似文献   

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ABSTRACT: In this paper, a system approach to water resources development in Tehran Metropolitan Area, with its complex system of water supply and demands, is discussed. Water resources in this region include water storage in the Lar, Latyan, and Karaj reservoirs, the Tehran aquifer, as well as water discharge in local rivers and in drainage channels (mainly supplied by urban runoff and wastewater). This study consists of three phases of long‐term water resources planning and management in the Tehran metropolitan area. In each phase, a different level of details among different components of the system is considered. In the first phase, optimal operating policies for Tehran reservoirs and a decision support system are developed. In the second phase, interactions between surface and ground water resources as well as surface runoffs and wastewater disposal in different subareas are investigated. The water table fluctuations as a result of implementing sewerage collection project was also simulated. In the last phase, long‐term scenarios for water resources and agricultural development in the Southern part of Tehran are defined, and the effects of each scenario on the quality and quantity of surface and ground water resources are studied.  相似文献   

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The crest-stage gage program in Louisiana was evaluated to determine if the data were adequate for use in developing regional flood-frequency equations and to determine if any crest-stage gage stations could be discontinued. An abundance of data at many crest-stage gage stations and a lack of data for urban areas and flat-slope areas indicated a need for a shift in the number, type, and locations of gages. Correlations and comparisons of annual peak discharges and watershed characteristics of 96 existing stations resulted in the elimination of 72 stations and the addition of one new station, reducing the total network to 25 stations that could be used for future flood-frequency analyses. The adequacy of the reduced network for development and verification of regional flood-frequency equations was tested by comparing a set of regional flood-frequency equations developed using data from the full network with a set developed using data from the reduced network. The results indicate that the crest-stage gage network can be reduced to 25 stations and still provide adequate information for future flood-frequency analyses.  相似文献   

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In this study, a constrained minimization method, the flexible tolerance method, was used to solve the optimization problems for determining hydrologic parameters in the root zone: water uptake rate, spatial root distribution, infiltration rate, and evaporation. Synthetic soil moisture data were first generated using the Richards' equation and its associated initial and boundary conditions, and these data were then used for the inverse analyses. The results of inverse simulation indicate the following. If the soil moisture data contain no noise, the rate of estimated water uptake and spatial root distribution parameters are equal to the true values without using constraints. If there is noise in the observed data, constraints must be used to improve the quality of the estimate results. In the estimation of rainfall infiltration and surface evaporation, interpolation methods should be used to reduce the number of unknowns. A fewer number of variables can improve the quality of inversely estimated parameters. Simultaneous estimation of spatial root distribution and water uptake rate or estimation of evaporation and water uptake rate is possible. The method was used to estimate the water uptake rate, spatial root distribution, infiltration rate, and evaporation using long‐term soil moisture data collected from Nebraska's Sand Hills.  相似文献   

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The route knowledge of participants who performed a concurrent task during a simulated route-learning exercise was compared to that of participants engaged only in the route-learning exercise by employing tests of scene recognition, distance estimation and map verification. Results indicated performance decrements on the scene recognition and distance estimation tasks on the part of participants in the concurrent task condition, thus supporting the interpretation that these tasks were sensitive to the reduction in available attentional resources. Performance on the map verification task was generally poor, a fact that may have masked the general effect of the concurrent task manipulation. Comparisons involving only those subgroups for which performance was above chance level provided evidence that this task was also sensitive to the availability of resources. In addition, results from the map verification task clearly pointed to map orientation as an important factor influencing the ability to recognize a cartographic representation of a path of movement within a large-scale environment.  相似文献   

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ABSTRACT: This paper computes estimates of the demand for surface irrigation water directly from disaggregated profit functions for fields in the San Joaquin Valley of California. It finds that treating delivered surface water and pumped ground water as separate, imperfectly substitutable inputs to production matters a great deal. We find substantial ranges of inelastic demand for delivered water, and thresholds across which demand then becomes highly elastic. The results imply that moves toward freer water markets could lead to large quantities reallocated from agriculture to urban uses in the Western U.S., but would require large price increases and would induce extensive ground water mining and major changes in cropping patterns. While these results are dependent on our particular model and simplifying assumptions, evidence exists that they may be robust.  相似文献   

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ABSTRACT Environmental resources can be managed properly only by adopting a comprehensive approach. The whole environment must be considered as a single system, and prior to any action, all types of environmental impacts caused by it should be studied in detail. This paper underlines the close relationship between different environmental problems, analyzes existing management patterns, and proposes new alternatives whenever applicable. The different constraints, which have to be considered in the decision-making process while developing a plan, are also discussed. It is concluded that efforts neglecting the interaction among different aspects of the environment do not upgrade the quality of water, air, and land to any appreciable degree.  相似文献   

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ABSTRACT: The objective is to develop techniques to evaluate how changes in basic data networks can improve accuracy of water supply forecasts for mountainous areas. The approach used was to first quantify how additional data would improve our knowledge of winter precipitation, and second to estimate how this knowledge translates, quantitatively, into improvement in forecast accuracy. A software system called DATANET was developed to analyze each specific gage network alternative. This system sets up a fine mesh of grid points over the basin. The long-term winter mean precipitation at each grid point is estimated using a simple atmospheric model of the orographic precipitation process. The mean runoff at each grid point is computed from the long-term mean precipitation estimate. The basic runoff model is calibrated to produce the observed long-term runoff. The error analysis is accomplished by comparing the error in forecasts based on the best possible estimate of precipitation using all available data with the error in the forecasts based on the best possible estimate of winter precipitation using only the gaged data. Different data network configurations of gage sites can be compared in terms of forecast errors.  相似文献   

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Abstract: Recent water sector reforms and increased scarcity and vulnerability of water resources, combined with declining public funding available for large scale infrastructure investment in the sector, have led to a greater awareness by the Government of Vietnam for the need to analyze water resource allocation and use in an integrated fashion, at the basin scale, and from a perspective of economic efficiency. In this study we focus on the development, application, and selected policy analyses using an integrated economic hydrologic river basin model for the Dong Nai River Basin in southern Vietnam. The model framework depicts the sectoral structure and location of water users (agriculture, industry, hydropower, domestic, and the environment) and the institutions for water allocation in the basin. Water benefit functions are developed for the major water uses subject to physical limitations and to constraints of system control and policy. Based on this modeling framework, we will analyze policies that can affect water allocation and use at the basin level, including both basin-specific and general macroeconomic policies.  相似文献   

19.
ABSTRACT The Colorado River Basin faces the dilemma of an increasing demand for water while presently struggling with salinity concentrations approaching critical levels for some water uses. Based upon projected development salinity concentrations are predicted to exceed 1200 mg/1 at Imperial Dam by the year 2010. Annual losses to the basin economy associated with increased salinity will exceed $50 million by the year 2010. Although methods of controlling salt discharges are relatively unrefined, certain conclusions, based upon Bayesian statistical methods, can be reached. Five basic alternatives for coping with the problem are presented and evaluated in this paper: (1) do nothing; (2) adopt arbitrary salinity standards; (3) limit development; (4) control salt discharges at a cost equal to the cost of doing nothing, or (5) minimize total costs to the basin. Total costs associated with any given alternative, or the given salinity resulting, are the sum of salinity detriments (cost to users for water of increased salinity plus economic multiplier effects) plus the cost of constructing salt discharge control works. These impacts upon basin economy and Colorado River water quality for each alternative are presented and related to questions of equity which will play a role in arriving at any long-term solution to the Basin's problem.  相似文献   

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Recent increases in energy prices have drawn attention to the importance of developing an integrated approach to energy sector planning, in contrast to the prevailing practice of uncoordinated planning in different energy sub-sectors. Integrated national energy planning (INEP) requires a clear definition of national objectives, in relation to which links between the energy sector, and activities in each individual sub-sector, may be analysed. Policy tools for achieving national goals include physical controls, technical methods, education and propaganda, and pricing. Use of these tools must be coordinated. The INEP procedure, which leads to an energy master plan, consists of several steps: determining the socio-economic background, supply and demand analysis, energy balance, and policy formulation. Initially INEP may be carried out at a relatively simple level, and later as data and analytical capabilities improve more sophisticated computerized modelling techniques could be implemented. The institutional structure should be rationalized by setting up a central energy authority (CEA) or ministry of energy (MOE), with its principal focus on energy planning and policy formulation. Les récentes hausses des prix de l'énergie ont révélé l'importance de l'élaboration d'une approche intégrée de la planification du secteur de l'énergie contrastant avec les pratiques courantes de planification non coordonnée qui existent dans les différents sous-secteurs de l'énergie. La planification nationale intégrée de l'énergie (PNIE) requiert une définition précise des objectifs nationaux à la lumière desquels on pourra analyser les liens existant entre le secteur de l'énergie et les autres secteurs de l'économie, les rapports entre les sous-secteurs à l'intérieur du secteur de l'énergie et les activités de chaque sous-secteur pris individuellement. Les contrôles directs, les méthodes techniques, l'enseignement, la publicité et la fixation des prix sont au nombre des moyens d'action dont dispose une telle politique pour parvenir aux objectifs nationaux. La procedure de la PNIE qui conduit â l'élaboration d'un plan-cadre en matière d'énergie comprend plusieurs étapes: détermination du contexte socio-économique, analyse de l'offre et de la demande, bilan énergétique et formulation politique. Dans une première étape, la PNIE peut être effectuée à un niveau relativement élémentaire et par la suite, au fur et à mesure que les donnés et les méthodes d'analyse s'améliorent, des techniques informatiques plus avancées en matiére d'établissement de modèlas pourraient étre utilisées. Le cadre institutionnel devrait être rationalise par la creation d'une autorité centrale de l'énergie ou d'un ministêre de l'énergie ayant pour tâche principale la planification de l'énergie et la formulation de politiques. Los recientes aumentos de los precios de energía resaltan la importancia de un enfoque integral en la planificación del sector de energía, en contraste a la practice generalizada de la planificación por subsectores de energía. La Planificación Energética Nacional Integrada (PENI) requiere una clara definición de objetivos nacionales en relación a los cuales pueden analizarse las relaciones entre el sector de energía y el resto de la economía, las inter-acciones entre los subsectores de energía y las actividades dentro de cada subsector. Las herramientas de política para alcanzar objetivos nacionales incluyen controles físicos, métodos técnicos, educación y propaganda, y precios. El procesco de PENI, que da como resultado un Plan Maestro de Energia, comprende varias etapas: determinación de las condiciones socioeconómicas, análisis de la demanda y la oferta, balance energético, y formulación de políticas. Al comienzo la PENI puede llevarse a cabo a un nivel relativamente simple; luego, cuando la información y la capacidad analítica mejoran se pueden implementar técnícas de modelización a base de computadoras. El marco institucional debe racionalizarse mediante la creación de una autoridad energética central o ministro de energía, encargado en particular de la formulación de políticas y la planificación energéticas.  相似文献   

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