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161.
M. Rodrigo-Gámiz F. Martínez-Ruiz F.J. Jiménez-Espejo D. Gallego-Torres V. Nieto-Moreno O. Romero D. Ariztegui 《Quaternary Science Reviews》2011,30(15-16):2018-2034
Eolian input fluctuations and paleoceanographic conditions in the western Mediterranean have been reconstructed by using a multi-proxy approach to infer climate variability for the last 20,000 yr. A sediment core from the East Alboran Sea basin provides high-resolution geochemical, mineralogical and grain size distribution records from the Last Glacial Maximum onward. The accurate chronology obtained, closely related with the North Greenland Ice core Project, has provided a detailed paleoclimate reconstruction at the centennial–millennial time scale. Mineral and chemical compositions as well as sediment grain size distribution have been used to establish both fluvial and eolian input variations, deep-water current intensity, and ventilation and productivity conditions at the time of deposition. During the cold period Greenland Stadial-2a, the analyzed proxies evidence significant climate oscillations. Redox proxies, showing marked Mn/Al and Fe/Al peaks, as well as granulometric parameters, support major changes in thermohaline circulation, with active circulation triggered by the Western Mediterranean Deep Water formation. Ba/Al ratios and the presence of authigenic barite point to high productivity during the Last Heinrich event. At this time, Zr/Al, Si/Al and Ti/Al ratios as well as quartz and palygorskite contents also corroborate dryer conditions in the Alboran borderlands, with a major reorganization of atmospheric circulation at the beginning of the deglaciation and during the Last Heinrich event. In contrast, a decreasing trend in the Zr/Al ratio and increasing Mg/Al, K/Al and illite + chlorite/kaolinite ratios would indicate enhanced river runoff and supporting lower eolian dust input and wetter periods during the Bölling–Alleröd. Short-term and abrupt climate oscillations such as the Intra-Alleröd Cold Period are likewise reflected by minor yet conspicuous changes in eolian proxies. During the Younger Dryas, we distinguish an initial cold and dry phase, with major westerlies intensity, thermohaline reactivation, and high productivity levels, and a second wetter phase characterized by sporadic rainfalls over poorly vegetated surrounding continental areas. Then, during the Holocene, alternating phases of major humidity and aridity were recorded by major fluctuations in detrital input. These are also correlated with recurrent forest cover declines reported from pollen records, with a noteworthy early decline in the African Humid Period. During the Holocene, an initial demise of the Last Organic-Rich Layer is also evidenced, tentatively associated with aspiration forces promoted by intense thermohaline circulation through the Gibraltar Strait. 相似文献
162.
Jordan is an Islamic state with planning based on Islamic principles. The execution of plans, though, has been constrained by geopolitical realities. In the last decade Jordan has moved from strictly sectoral planning to a strongly focused system of regional planning in order to achieve more growth in less developed regions. The prospects for these regions and the country as a whole will turn on the success of the peace process in the region. 相似文献
163.
J. L.?Pérez-RodríguezEmail author J.?Poyato M. C.?Jiménez de Haro L. A.?Pérez-Maqueda A.?Lerf 《Physics and Chemistry of Minerals》2004,31(7):415-420
The investigation of the NH3 loss in the NH4+-vermiculite (Santa Olalla) by thermogravimetry, evolved gas analysis, chemical analysis, X-ray diffraction and IR spectroscopy is reported here. The mass loss during heating takes place in two steps at about 650 and 825 °C. Additionally, the releases of H2O and NH3 occurs simultaneously. The experimental results indicate that the protons remaining in the interlayer space after NH3 removal trigger the H2O release. X-ray diffraction shows that during the decomposition of NH4+-vermiculite there are two domains with different interlayer spaces at ~9 and ~10 Å. As the decomposition proceeds, the intensity of the 9 Å peak increases at the expense of the second one. The change in the IR-stretching modes of the structural OH groups during heating indicates that the OH groups surrounded by 3Mg2+ or 2Mg2+Fe2+ are released at lower temperatures than those with environments like 2Mg2+Fe3+, 2Mg2+Al3+ or more complex ones. 相似文献
164.
165.
Mohamed?ChebaaneEmail author Hazim?El-Naser Jim?Fitch Amal?Hijazi Amer?Jabbarin 《Hydrogeology Journal》2004,12(1):14-32
Groundwater over-exploitation has been on the rise in Jordan. Competing demands have grown in the face of perennial water shortages, a situation which has been exacerbated by drought conditions in the past decade. This paper reports findings of a project in which management options to address over-exploitation were developed for one of Jordans principal aquifer systems, the Amman-Zarqa Basin. Options for addressing the situation were developed through a participatory approach that involved government officials and various public and private sector interest groups. Particular efforts were made to involve well irrigators, who are likely to be heavily impacted by the changes required to reduce groundwater pumping to a sustainable level. With information obtained from a rapid appraisal survey as well as from interviews with farmers, community groups, government officials, and technical experts, an extensive set of options was identified for evaluation. Based on integrated hydrogeologic, social, and economic analysis, five complementary management options were recommended for implementation. These included the establishment of an Irrigation Advisory Service, buying out farm wells, placing firm limits on well abstraction and irrigated crop areas, exchanging treated wastewater for groundwater, and measures to increase the efficiency of municipal and industrial water use. Various combinations and levels of these options were grouped in scenarios, representing possible implementation strategies. The scenarios were designed to assist decision makers, well owners and other stakeholders in moving gradually towards a sustainable abstraction regime. Social and economic aspects of each option and scenario were analyzed and presented to stakeholders, together with a summary of legal, institutional and environmental ramifications. Combining scientific analysis with a participatory approach in the Amman Zarqa Basin groundwater management was devised as a prototype to be used in the management of other groundwater basins in Jordan. This participatory management approach would also be useful in other parts of the world that are experiencing similar groundwater over-exploitation problems.Résumé La surexploitation des eaux souterraines prend de limportance en Jordanie. Les demandes en concurrence ont augmenté face à des déficits permanents deau, situation qui a été exacerbée par la sécheresse de la dernière décennie. Cet article rend compte de laboutissement dun projet dans lequel des options de gestion portant sur la surexploitation ont été développées pour lun des principaux systèmes aquifères de Jordanie, le bassin dAmman Zarqa. Des options pour aborder cette situation ont été développées grâce à une approche participative qui implique des fonctionnaires du gouvernement et des groupes dintérêts variés des secteurs public et privé. Des efforts particuliers ont été faits pour impliquer les irrigants utilisant des puits, qui sont probablement ceux qui ont le plus fort impact sur les changements attendus permettant de remettre le système en équilibre. À partir des informations obtenues de campagnes rapides dévaluation, telles que des réunions de communautés et des entrevues avec des experts techniques du gouvernement, un large jeu doptions a été identifié pour lévaluation. Basées sur une analyse hydrogéologique, sociale et économique, cinq options complémentaires de gestion ont été recommandées pour la réalisation. Ce sont la création dun Service Consultatif dIrrigation, achetant les puits agricoles, fixant des limites fermes aux prélèvements des puits et aux zones irriguées, échangeant les eaux usées traitées avec des eaux souterraines, et la mise en place de mesures pour accroître lefficacité des usages collectifs et industriels. Des combinaisons et des niveaux variés de ces options ont été regroupés en scénarios, présentant les stratégies possibles de mise en uvre. Les scénarios ont été mis au point pour assister les décideurs, les propriétaires de puits et les autres acteurs pour atteindre progressivement un régime de prélèvement durable. Les aspects sociaux et économiques de chaque option et de chaque scénario ont été analysés et présentés aux acteurs, en même temps quun résumé des ramifications légales, institutionnelles et environnementales. En combinant une analyse scientifique à une approche participative du bassin dAmman Zarqa, la gestion des eaux souterraines a été imaginée comme un prototype pouvant être utilisé pour la gestion dautres bassins aquifères de Jordanie. Il peut également être utile à dautres régions du monde qui sont concernées par des problèmes similaires de surexploitation des eaux souterraines.Resumen La sobreexplotación de las aguas subterráneas ha ido en aumento en Jordania, donde las demandas en competición han crecido frente a una escasez perenne de agua, situación que ha sido agravada por el estado de sequía de la última década. Este artículo presenta los hallazgos de un proyecto en el que se han desarrollado opciones de gestión para hacer frente a la sobreexplotación en uno de los principales sistemas acuíferos de Jordania: la cuenca de Ammán-Zarga. Se ha elaborado opciones para afrontar la situación mediante un enfoque participativo que incluye a personal del gobierno y a diversos grupos de interés de los sectores público y privado. En particular, se ha intentado involucrar a los regantes que se sirven de aguas subterráneas, quienes tienen más probabilidad de ser directamente afectados por los cambios requeridos para devolver el sistema a un balance equilibrado. A partir de la información obtenida en rápidas campañas de valoración, así como de encuentros con la comunidad y entrevistas con los expertos técnicos del gobierno, se ha identificado un amplio conjunto de opciones para su evaluación. Basándose en un análisis integrado de los aspectos hidrogeológicos, sociales y económicos, se ha recomendado la implementación de cinco opciones complementarias de gestión: establecimiento de un Servicio Asesor de Riego; adquisición de pozos de granjas; imposición de límites estrictos en las extracciones de pozos y superficies de riego; substitución de las aguas subterráneas con aguas residuales depuradas; y medidas para incrementar la eficiencia de los usos municipales e industriales del agua. Se ha agrupado varias combinaciones y niveles de dichas opciones en escenarios, representando estrategias posibles de implementación. Los escenarios han sido diseñados para ayudar a los gestores en la toma de decisiones, a los propietarios de pozos y a otros agentes para que se vaya consiguiendo de forma gradual un régimen de extracciones sustentable. Se ha analizado los aspectos sociales y económicos de cada opción y de cada escenario, presentándolos a los diversos agentes, además de generar un resumen de ramificaciones legales, institucionales y medioambientales. Se ha concebido la combinación de un análisis científico con un enfoque participativo en la cuenca de Ammán-Zarga como un prototipo de gestión de las aguas subterráneas que puede ser aplicado a la gestión de otras cuencas en Jordania. También sería útil en otros lugares del mundo que estén experimentando problemas similares de sobreexplotación de los recursos hídricos subterráneos.Abbreviations and acronyms AED
Academy for Educational Development
- ARD
Associates in Rural Development
- AZB
Amman–Zarqa Basin
- ECC
Economic Consultative Council
- GMCC
Groundwater Management Consultative Committee
- GMF
Groundwater Management Fund
- GIS
Geographic Information System
- HDH
Hashmiya–Dulayl–Hallabat
- IAS
Irrigation Advisory Service
- JICA
Japanese International Cooperation Agency
- M&I
Municipal and Industrial
- MOA
Ministry of Agriculture
- MWI
Ministry of Water and Irrigation
- NCARTT
National Center for Agricultural Research and Technology Transfer
- NGO
Non-governmental Organization
- O&M
Operations and Maintenance
- RA
Rapid Appraisal
- RS
Remote Sensing
- UFW
Unaccounted for Water
- USAID
United States Agency for International Development
- WAJ
Water Authority of Jordan
- WEPIA
Water Education & Public Information Activity
- WRPS
Water Resource Policy Support 相似文献
166.
Stepwise use of GFLOW and MODFLOW to determine relative importance of shallow and deep receptors 总被引:1,自引:0,他引:1
A stepwise modeling approach is implemented in which a regional one-layer analytic element model is used to simulate the flow system and to furnish boundary conditions for an extracted local three-dimensional model. In this case study the stepwise approach is used to evaluate the fate of recharge in the Menomonee Valley adjacent to Lake Michigan. Two major receptors exist for recharge that flows through contaminated valley fill: the surface water estuary and a tunnel system constructed approximately 75 to 110 m below land surface to store storm runoff. The primary objective of the modeling is to delineate the contributing areas of recharge to each receptor. Of interest is the ability of the one-layer regional model to furnish flux boundary conditions to the local three-dimensional model despite the presence of vertical flow conditions at the boundaries of the local model. Sensitivity analysis suggests that the local model was insensitive to the vertical distribution of the flux. Each step of the modeling approach demonstrates that both receptors play an important role in capturing valley recharge. The pattern of capture of the one-layer model differed in shape from that delineated by the multi-layer local model in the presence of a flow system with pronounced vertical anisotropy and with sinks drawing water from different elevations. 相似文献
167.
Application of harmonic analysis of water levels to determine vertical hydraulic conductivities in clay-rich aquitards 总被引:1,自引:0,他引:1
A harmonic analysis method was used to determine vertical hydraulic conductivities (Kv) in geologic media between vertically separated piezometers using water level measurements. In this method, each water level time series was filtered and then decomposed using harmonic analysis into a sum of trigonometric components. The phase and amplitude of each harmonic function were calculated. These data were used to estimate Kv values between vertically separated data sets assuming one-dimensional transient flow. The method was applied to water level data collected from nested piezometers at two thick clay-rich till aquitards in Saskatchewan, Canada. At one site, routine water levels were measured in 12 piezometers (installed between 1 and 29 m below ground surface) since installation (1995). At the other site, water levels were measured in seven piezometers (installed between 4 and 53 m below ground surface) since installation (1998-1999). The Kv calculated using harmonic analysis decreased with depth below the water table at both sites, approaching matrix estimates of hydraulic conductivity between 10 and 11 m and between 21 and 43 m below ground surface. These depths reflected the depth of extensive vertical fracturing at the sites and showed that the depth of fracturing may be site specific. 相似文献
168.
Chemistry of springs across the Mariana forearc shows progressive devolatilization of the subducting plate 总被引:3,自引:0,他引:3
Michael J. Mottl C. Geoffrey Wheat Jim Gharib 《Geochimica et cosmochimica acta》2004,68(23):4915-4933
Cold springs upwelling through large serpentinite mud volcanoes in the outer half of the Mariana forearc provide a unique window into processes of devolatilization of the subducting Pacific Plate. We have sampled upwelling pore waters with lower chlorinity than seawater from six sites on five serpentinite mud volcanoes, by conventional gravity and piston coring, by push coring from the ROV Jason, by drilling on ODP Legs 125 and 195, and by manned submersible. The sites range from 13°47′N to 19°33′N and 52 to 90 km from the Mariana trench axis, corresponding to approximate depths to the top of the downgoing plate of 16 to 29 km. The composition of the springs varies systematically over this distance: nearer the trench the upwelling waters have much higher Ca and Sr than seawater and much lower carbonate alkalinity, sulfate, Na/Cl, K, Rb, and B. Farther from the trench the waters show the opposite trends relative to seawater. Chlorinity is consistently lower than in seawater and shows large variations that are not systematic with distance from the trench. Cs is consistently higher than in seawater and increases with distance from the trench. All of the waters have high pH and are heavily depleted in Mg, Si, Li, F, and 87Sr/86Sr relative to seawater. They tend to be enriched in O18/O16. Except for ODP drilling, none of the cores was long enough to produce an asymptotic compositional trend with depth. We have inferred the end-member compositions of the upwelling waters by extrapolation against Mg. At two sites we were able to compare data from gravity cores with data from drill cores or push cores collected at springs to estimate the effects of reactions that occur at shallow depth below the seafloor, on mixing of the upwelling waters with seawater. These effects are different for sites high in dissolved Ca, nearer the trench, vs. those high in alkalinity, farther from the trench. Common to both are large losses from solution of 1) Ca, as CaCO3 and in exchange for Na; 2) Mg, in exchange for Na or Ca and as brucite; 3) sulfate, probably reduced by microbes or possibly precipitated as gypsum; 4) Sr, Ba, Si, and F. Na is consistently leached from the solids into solution, whereas K and O18/O16 are relatively unreactive.We infer that the upwelling waters are uniformly saturated with CaCO3 and that the excess H2O and the trends in Ca, Sr, alkalinity, and sulfate with distance from the trench result from introduction of H2O and dissolved carbonate and sulfate from an external source, the sediment and altered basalt at the top of the subducting plate. The concurrent trends in Na/Cl, B, Cs, and especially K and Rb indicate that these species originate from the top of the subducting plate in response to increasing temperature. These systematic variations across the outer forearc imply that the solutions ascend more or less vertically from the source region and do not travel long distances laterally along the décollement before ascending. Based on leaching of K, the 150°C isotherm is crossed approximately beneath Big Blue Seamount at a depth of ∼22 km below the seafloor, 70 km behind the trench. By this point it appears that carbonate dissolution has joined dehydration as a significant process at the top of the subducting plate. 相似文献
169.
David Besson Olivier Parize Jean-Loup Rubino Jean-Pierre Aguilar Marie-Pierre Aubry Bernard Beaudoin William A. Berggren Georges Clauzon Philippe Crumeyrolle Yann Dexcoté Nicolas Fiet Silvia Iaccarino Gonzalo Jiménez-Moreno Cécile Laporte-Galaa Jacques Michaux Katharina von Salis Jean-Pierre Suc Jean-Yves Reynaud Roland Wernli 《Comptes Rendus Geoscience》2005,337(12):1045-1054
An integrated study combining facies analysis, multiple group biostratigraphy, identification of depositional sequences and mapping has been conducted on the Miocene Molasse Basin of the external Alps (southeastern France). The filling of the basin is described as resulting from a succession of fluvial incisions subsequently filled during marine transgressions. The major incision is dated as Latest Burdigalian and the major transgression as Langhian. This revised interpretation of the Miocene physiographic evolution of the Molasse Basin implies a re-examination of previous stratigraphic correlations within the basin. To cite this article: D. Besson et al., C. R. Geoscience 337 (2005). 相似文献
170.
Few sources exist to draw generalizations about the incredibly diverse international river restoration community. Generalizations in the restoration literature tend to be grounded on individual experiences or logical conjecture. To fill this perceived gap, an international web-based survey was launched. Over 500 respondents from 37 different countries participated. The results, posted on the web, act as a database of perceptions and individual experiences, from which the restoration community can make their own interpretations. With three examples, we contrast scientific conjecture with the perceptions of the restoration community who participated in this survey. 相似文献