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1.
The signal to noise ratio in tidal data in the diurnal and semidiurnal frequency bands is ordinarily so large that the noise contribution to the tidal harmonic constants is unimportant. However, as the observational locations are selected progressively closer to an amphidrome (point of no tide), the signal to noise ratio decreases, making the tidal harmonic constants less dependable. Standard deviations in amplitude of M2 and S2 obtained from 12 29-day analyses of a year of tide data obtained at a standard tide station, estimated to be 280 and 550 km away from the amphidromes for these constituents in the eastern Caribbean, are roughly one-third of the mean amplitudes for these constituents; the standard deviations in epoch are 38° and 30° respectively. Therefore, a program to locate an amphidrome precisely is self-defeating and the location can only be approximated by a grid of tide observations spanning the geographic position and/or by longer series of observations, using higher resolution to increase the signal to noise ratio. Amplitudes of 0.64 cm and 1.24 cm were calculated for M2 and S2 from a one-month series of pelagic observations obtained very close to an inferred position of the M2 amphidrome in the northeast Caribbean Sea.Abbreviations C&GS Coast and Geodetic Survey - CICAR Cooperative Investigation of the Caribbean and Adjacent Regions - IAPSO International Association for the Physical Sciences of the Ocean - ICOT Institute of Coastal Oceanography and Tides - IDOE International Decade of Ocean Exploration - NOAA National Oceanic and Atmospheric Administration - NOS National Ocean Survey - NSF National Science Foundation - SCOR Scientific Committee of Oceanic Research - UNESCO United Nations Educational, Scientific, and Cultural Organization  相似文献   

2.
Puri S  Aureli A 《Ground water》2005,43(5):661-668
Transboundary aquifers are as important a component of global water resource systems as are transboundary rivers; yet, their recognition in international water policy and legislation is very limited. Existing international conventions and agreements barely address aquifers and their resources. To rectify this deficiency, the International Association of Hydrogeologists and UNESCO's International Hydrological Programme have established the Internationally Shared (transboundary) Aquifer Resource Management (ISARM) Programme. This multiagency cooperative program has launched a number of global and regional initiatives. These are designed to delineate and analyze transboundary aquifer systems and to encourage riparian states to work cooperatively toward mutually beneficial and sustainable aquifer development. The agencies participating in ISARM include international and regional organizations (e.g., Organization of American States, United Nations Environment Programme, United Nations Economic Commission for Europe, Food and Agriculture Organization, and South African Development Community). Using outputs of case studies, the ISARM Programme is building scientific, legal, environmental, socioeconomic, and institutional guidelines and recommendations to aid sharing nations in the management of their transboundary aquifers. Since its start in 2000, the program has completed inventories of transboundary aquifers in the Americas and Africa, and several ISARM case studies have commenced.  相似文献   

3.
Arnold GE  Buzás Z 《Ground water》2005,43(5):669-678
In Europe, a long history of cooperation over transboundary rivers--most notably the Rhine and Danube rivers--exists. To help foster cooperation and communication vis-à-vis transboundary ground water, the United Nations Economic Commission for Europe (UNECE), as part of its ground water program, conducted a survey on transboundary aquifers in Europe. The survey produced 25 responses from 37 countries and identified 89 transboundary aquifers. Respondents reported on the degree of ground water use within their own boundaries, transboundary aspects (agreements, joint commissions, etc.) of ground water, and transboundary aquifers themselves. The inventory proved useful, but a number of problems were identified: different map scales and symbols, difficulty in identifying transboundary aquifers, inconsistent labeling of aquifers, and data discrepancies. The UNECE ground water program also drafted guidelines for monitoring and assessment of transboundary ground water. These guidelines are not legally binding but have been adopted by 25 countries, deal mainly with monitoring and assessment, and are being implemented through a number of pilot projects. Other organizations-the United Nations Scientific, Educational and Cultural Organization, the Food and Agriculture Organization, the International Association of Hydrogeologists, and the European Union--are all supporting the investigation of transboundary aquifers in an effort to facilitate data sharing and coordinated management of these valuable resources.  相似文献   

4.
Almost 5 years after the 26 December 2004 Indian Ocean tragedy, the 10 August 2009 Andaman tsunami demonstrated that accurate forecasting is possible using the tsunami community modeling tool Community Model Interface for Tsunamis (ComMIT). ComMIT is designed for ease of use, and allows dissemination of results to the community while addressing concerns associated with proprietary issues of bathymetry and topography. It uses initial conditions from a precomputed propagation database, has an easy-to-interpret graphical interface, and requires only portable hardware. ComMIT was initially developed for Indian Ocean countries with support from the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the United States Agency for International Development (USAID), and the National Oceanic and Atmospheric Administration (NOAA). To date, more than 60 scientists from 17 countries in the Indian Ocean have been trained and are using it in operational inundation mapping.  相似文献   

5.
The Ninth International Symposium on River Sedimentation (9th ISRS) has been successfully held on Oct. 18 to 21, 2004 at the site of the partially completed Three Gorges Project on the Yangtze River near Yichang of Hubei Province, China. The Symposium is organized by the Ministry of Water Resources, People's Republic of China (MWR), sponsored by International Research and Training Center on Erosion and Sedimentation (IRTCES), Changjiang River Water Resources Commission (CWRC), China Institute of Water Resources and Hydropower Research (IWHR) and Chinese Hydraulic Engineering Society (CHES). Twenty nine organizations including the United Nations Educational, Scientific and Cultural Organization (UNESCO), International Association of Hydraulic Engineering and Research (IAHR), International Association for Hydrological Sciences (IAHS) and National Natural Science Foundation of China (NSFC) are co-sponsors.  相似文献   

6.
This paper presents the mathematical development of an integer — nonlinear programming chance — constrained optimization model for the minimum cost rehabilitation/replacement of water distribution system components. Particular attention is given to the handling of uncertainties in the roughness factors and the loading conditions including both the random demand and preassure head requirements.The advantages of the proposed model include the ability to: 1) handle the optimal timing of rehabilitation/replacement for water distribution system components; 2) link a mixed-integer linear program solver, a nonlinear program solver, and a hydraulic simulator into an optimization framework; 3) handle the uncertainties of some of the variables; 4) incorporate various kinds of cost functions; and 5) handle multiple loading conditions.  相似文献   

7.
This paper presents the mathematical development of an integer — nonlinear programming chance — constrained optimization model for the minimum cost rehabilitation/replacement of water distribution system components. Particular attention is given to the handling of uncertainties in the roughness factors and the loading conditions including both the random demand and preassure head requirements.The advantages of the proposed model include the ability to: 1) handle the optimal timing of rehabilitation/replacement for water distribution system components; 2) link a mixed-integer linear program solver, a nonlinear program solver, and a hydraulic simulator into an optimization framework; 3) handle the uncertainties of some of the variables; 4) incorporate various kinds of cost functions; and 5) handle multiple loading conditions.  相似文献   

8.
Maps of faults (geologically defined source zones) may portray seismic hazards in a wide range of completeness depending on which types of faults are shown. Three fault terms — active, capable, and potential — are used in a variety of ways for different reasons or applications. Nevertheless, to be useful for seismic-hazards analysis, fault maps should encompass a time interval that includes several earthquake cycles. For example, if the common recurrence in an area is 20,000–50,000 years, then maps should include faults that are 50,000–100,000 years old (two to five typical earthquake cycles), thus allowing for temporal variability in slip rate and recurrence intervals. Conversely, in more active areas such as plate boundaries, maps showing faults that are <10,000 years old should include those with at least 2 to as many as 20 paleoearthquakes. For the International Lithosphere Programs’ Task Group II-2 Project on Major Active Faults of the World our maps and database will show five age categories and four slip rate categories that allow one to select differing time spans and activity rates for seismic-hazard analysis depending on tectonic regime. The maps are accompanied by a database that describes evidence for Quaternary faulting, geomorphic expression, and paleoseismic parameters (slip rate, recurrence interval and time of most recent surface faulting). These maps and databases provide an inventory of faults that would be defined as active, capable, and potentially active for seismic-hazard assessments.  相似文献   

9.
How might an international plan for crustal-movement studies in Africa be implemented? This was the basic question underlying much of the discussion at the First International Symposium on Crustal Movements in Africa, convened in May 1981 in Addis Ababa at the United Nations Economic Commission for Africa. Three years later, in November/December 1984, the Second Symposium was held in Cairo, Egypt; and in April 1986, some outstanding questions were dealt with at the Third Symposium on Geodesy in Africa held in Yamoussoukro, Ivory Coast, and at the International Symposium on Global Changes in Africa during the Quaternary, held in Dakar, Senegal.The present state and possible development of recent crustal movement studies in Africa are discussed. Finally, the cooperation of all scientists interested in such studies is solicited.  相似文献   

10.
《Water Policy》2001,3(5):405-423
This paper examines the fit between water and environmental quality issues as articulated in the Law of the Non-navigational Uses of International Watercourses approved by the United Nations General Assembly in 1997 and the water provisions that were included in the Israel–Jordan Treaty of 1994 and the Israel–Palestinian Authority Accord of 1995. It also examines the differences and commonalities of the two agreements with regard to these issues and examines the process of implementation to date.  相似文献   

11.
Summary Temperature records of a long period (1858–1952) for Athens, in the form of overlapping 30-year intervals, are analyzed with a view to be investigated temperature trends.While the winter temperature has been rising almost continously during the period under consideration, the increase of summer temperature — to which the annual temperature and the annual temperature range as well are rather similar — has occured altogether during the second half of the record. During the first half the summer and annual temperatures and the annual range were all decreasing. The oceanicity increased during the first half and decreased during the second.The total change has been a rise of 0.90 deg. in winter temperature, a fall of 0.7 followed by a rise of 1.00 deg. in summer temperature, and a fall of 0.3 then a rise of 0.70 deg. in annual temperature.The rapid increase of population and also variations in solar activity seem to have partly influenced the Athens temperature trends.Presented at the tenth General Assembly of the International Union of Geodesy and Geophysics in Rome (Italy), September 1954.  相似文献   

12.
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13.
Zusammenfassung Die Vorstellungen über die Elektrizitätsbildung in den Gewitterwolken erlauben die Annahme, dass diese Elektrizitätsbildung ein Mass für die in den Wolken vorhandene Gesamt-Niederschlagsmenge liefern kann. Zur überprüfung dessen werden die Ladungsbildungen — charakterisiert durch die Häufigkeit der Entladungen - und die Gesamt-Niederschlagsmenge — gemessen durch den Zufluss zu einer Talsperre — miteinander korreliert. Der erichen diese für eine quantitative Verknüpfung noch nicht aus. Zur besseren Niederschlagserfassung sind Radarbeobachtungen in Aussicht genommen.
Summary The conceptions on the formation of electricity in thunderclouds permit to accept that the formation of electricity may provide a measure for the entire amount of precipitation existing in the clouds. In order to examine this idea the formation of charge — characterized by the number of discharges - and the total amount of precipitation — given by the flowing in to a barrage — are correlated with each other. The relationship expected following from the results so far obtained exists for the present only in a qualitative manner because the measurement of the total amount of precipitation by means of a barrage is too inexact. For a better registration of the precipitation amount radar-observations are planned.
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14.
Access to fresh water is one of the major issues of northern and sub-Saharan Africa. The majority of the fresh water used for drinking and irrigation is obtained from large ground water basins where there is minor contemporary recharge and the aquifers cross national borders. These aquifers include the Nubian Aquifer System shared by Chad, Egypt, Libya, and Sudan; the Iullemeden Aquifer System, extending over Niger, Nigeria, Mali, Benin, and Algeria; and the Northwest Sahara Aquifer System shared by Algeria, Libya, and Tunisia. These resources are subject to increased exploitation and may be severely stressed if not managed properly as witnessed already by declining water levels. In order to make appropriate decisions for the sustainable management of these shared water resources, planners and managers in different countries need an improved knowledge base of hydrological information. Three technical cooperation projects related to aquifer systems will be implemented by the International Atomic Energy Agency, in collaboration with the United Nations Educational, Scientific and Cultural Organization and United Nations Development Programme/Global Environmental Facility. These projects focus on isotope hydrology studies to better quantify ground water recharge and dynamics. The multiple isotope approach combining commonly used isotopes 18O and 2H together with more recently developed techniques (chlorofluorocarbons, 36Cl, noble gases) will be applied to improve the conceptual model to study stratification and ground water flows. Moreover, the isotopes will be an important indicator of changes in the aquifer due to water abstraction, and therefore they will assist in the effort to establish a sustainable ground water management.  相似文献   

15.
Summary In order to examine the explanation put forward to us privately that the marked influence of the air-flow on the value of the diffusion coefficient as determined by the dynamic method is due to unequal flow through the channels of the diffusion apparatus used hitherto, a novel diffuser — called Universal Diffusion Battery — has been constructed in which the air-flow through each channel can be equalised.The new diffusion battery is described and its advantages outlined. Its application also shows that with equal flow through each channel the dependence of the diffusion coefficient on the air-flow (i.e. that higher diffusion constants with higher flow rates are obtained) still exists. A comparison of the diffusion coefficients as measured with the diffusion batteries of the old and new types is given.The explanation based on irrefutable theoretical considerations that this dependence of the diffusion coefficient on the air-flow is caused by the heterogeneity of the condensation nuclei in the aerosol, as given byPollak & Metnieks some time ago, is apparently the correct one or it accounts at least for the greatest part of the phenomenon.
Zussamenfassung Um die Erklärung, welche uns privat mitgeteilt wurde, zu prüfen, dass der ausgesprochene Einfluss der Luftstromgeschwindigkeit auf die Grösse des mit der dynamischen Methode bestimmten Diffusionskoeffizienten der verschiedenen Durchströmung der Kanäle des bisher verwendeten Diffusionsapparates zuzuschreiben ist, wurde ein neuartiger Diffusionsapparat, den wir «Universelle Diffusions Batterie» nennen, konstruiert, in welchem die Luftstromgeschwindigkeit durch jeden Kanal gleichgemacht werden kann.Die neue Diffusionsbatterie und ihre Vorteile werden beschrieben. Ihre Anwendung zeigt, dass auch mit gleicher Luftstromgeschwindigkeit durch jeden Kanal die Abhängigkeit der Diffusionskoeffizienten von der Luftstromgeschwindigkeit — nämlich, dass höhere Diffusionskonstanten mit grösseren Luftstromgeschwindigkeiten erhalten werden — doch besteht. Es werden die Resultate einer Vergleichung der Werte des Diffusionskoeffizienten, wie siebei Benützung der Diffusionsapparate der alten und neuen Bauart erhalten werden, mitgeteilt.Die Erklärung, welche sich auf unwiderlegbare theoretische Überlegungen stützt, dass die Abhängigkeit des Diffusionskoeffizienten von der Luftstromgeschwindigkeit durch die Heterogenität der Kondensationskerne verursacht wird — wie sie vor einiger Zeit vonPollak & Metnieks, gegeben wurde — scheint die richtige zu sein oder erfasst wenigstens den grössten Teil der Erscheinung.

The research reported in this article has been sponsored and supported in part by the Geophysics Research Directorate of the Air Force Cambridge Research Center, Air Research and Development Command, United States Air Force, under Contract AF 61(052)-26, through the European Office, ARDC in Brussels.  相似文献   

16.
Nutrients migrating from agrocenoses through drainage effluents are retained in a field pond. Studies were carried out concerning the effectiveness of this process in an aquatic environment in the conditions of development of phytoplankton and submersed and floating-leaved macrophytes (1987), in the state of phytoplankton dominance (1988), and, in a swamp environment, in the state of dominance of emergent macrophytes (1991).The greatest effectiveness of this process was found in the conditions of development of aquatic plants, i.e. submersed and folating-leaved macrophytes and phytoplankton. In the warm season of 1987 the retention of nutrients (in g · m–2) was: TN — 7.20, TP — 3.5, K — 3.80, Ca — 119, and Mg — 8.2. When the euglenoid phytoplankton dominated, the level of retention was slightly higher and the export of Norg was also noted (3.27 g · m–2 season–1). In the case of dominance of emergent macrophytes, a reduction in the TN load, particularly in N-NO3 (by 3.67 m–2 season–1), occurred, though at the same time a release of P, K, and Mg was noted. The export exceeded the import of TP by 0.44, K by 15.3, and Mg by 1.4 g · m–1. The conditions for the functioning of a field pond as a sink for nutrients migrating from agroecosystems to surface waters were determined.  相似文献   

17.
The practically important part of geothermal systems belongs to the convective type where the thermal energy is transported by movement of water or steam. Both geothermics and hydrology should be in very close cooperation at the interpretation of convective geothermal anomalies.In the first part of the study the parameters required for the calculation of water- and thermal-balance will be enumerated and their obtainable accuracy will be discussed based mainly on the praxis used in Hungary.In the second part, heat convection problems connected to subterranean water movement will be discussed, divided into three cases which have importance in praxis:
• — regional water-flow systems with great inflow and outflow areas;
• — mountainous — mainly karstic — areas of infiltration with springs at the foot of the mountain;
• — closed convective systems of circulation.
For illustrating the conceptual examples given above, Hungarian case histories with characteristic data will be presented: The Transdanubian Middle Range, Spa of Budapest, Spa of Héviz, the Great Hungarian Plain and the Thermal Anomaly at Tiszakécske.  相似文献   

18.
Summary The radioactivity in different parts of a cloud as well as the radioactivity of the atmosphere before and after the cloud's passage are examined with stationary samplers — fall-out pans, Grunow cloud-catchers of various materials, and air-pumps — at elevations of 1800 m and 2817 m, on Mt Olympus — Greece. The relation between the cloud's density and its radioactivity is also examined.  相似文献   

19.
A model for determining the optimal operation of Israel's National Water System over 1 year, with monthly time increments, is described. The water system contains the Main National Carrier — some 250 km long from the Kinneret (Sea of Galillee) in the north to the Negev region in the south — and some 25 regional water systems connected to it. Water is taken from the Kinneret and from two aquifers. Water transfers may take place between the National Carrier and regional systems, and between interconnected regional systems.The mathematical model of the system represents its monthly production and transfer capacities. Given the monthly demands which have to be met and the hydraulic constraints the model determines the month-by-month operating plan which minimizes energy costs over the year.The optimization model is formulated as a linear program. This necessitates several types of approximations and linearizations, which are discussed in detail. The optimal operating plan for 1977–78 is compared with the actual operation of that year and conclusions are drawn from the comparison concerning the practicality and adequacy of the model's output and the potential for effective operation and for energy savings.  相似文献   

20.
Zusammenfassung Aus den bei Ballonaufstiegen, bei Mondfinsternissen und durch den Umkehreffekt gemessenen Ozonverteilungen werden für verschiedene geographische Breiten gemittelte Ozonverteilungen abgeleitet und mit den theoretisch photochemisch berechneten Verteilungen verglichen, wodurch der Spielraum der letzten erheblich eingeengt wird. — Die Diskrepanz zwischen der berechneten und der gemessenen Ozonverteilung unterhalb des Ozonmaximums in 23 km Höhe lässt auf eine bedeutende Wirkung des Massenaustausches in der Troposphäre und in der unteren Stratosphäre schliessen, der nach den Aequator hin stark zunimmt. — In mittleren und höheren Breiten tritt — vornehmlich im Frühjahr — ein zweites tieferes Ozonmaximum in 16 km Höhe auf, das photochemisch nicht zu erklären ist, sondern advektiv, durch aus polaren Breiten herzugeführtes Ozon bedingt wird.
Summary The mean ozone distribution for various geographical latitudes is derived from ozone distributions measured by means of balloon ascents, eclipses of the moon and the «Umkehreffekt» and compared with the theoretically calculated photochemical distributions, whereby the full scope of the latter is considerably limited. —The discrepancy between the calculated and the measured ozone distribution below the ozone maximum at 23 km altitude is a sign of a considerable effect of mass exchange in the troposphere and lower stratosphere which increases towards the equator. In the mean and higher latitudes we find — especially in spring — a second lower ozone maximum at 16 km altitude which cannot be explained photochemically but is probably due to advection, to ozone transported down from polar latitudes.
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