Stable and radio-isotope analysis to determine recharge timing and paleoclimate of sandstone aquifers in central and southeast Libya     

Mohamed Al Faitouri  William E. Sanford 《Hydrogeology Journal》2015,23(4):707-717

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Multi-factor impact analysis of agricultural production in Bangladesh with climate change   总被引：1，自引：0，他引：1  

Alex C. Ruane  David C. Major  Winston H. Yu  Mozaharul Alam  Sk. Ghulam Hussain  Abu Saleh Khan  Ahmadul Hassan  Bhuiya Md. Tamim Al Hossain  Richard Goldberg  Radley M. Horton  Cynthia Rosenzweig 《Global Environmental Change》2013,23(1):338-350

Diverse vulnerabilities of Bangladesh's agricultural sector in 16 sub-regions are assessed using experiments designed to investigate climate impact factors in isolation and in combination. Climate information from a suite of global climate models (GCMs) is used to drive models assessing the agricultural impact of changes in temperature, precipitation, carbon dioxide concentrations, river floods, and sea level rise for the 2040–2069 period in comparison to a historical baseline. Using the multi-factor impacts analysis framework developed in Yu et al. (2010), this study provides new sub-regional vulnerability analyses and quantifies key uncertainties in climate and production. Rice (aman, boro, and aus seasons) and wheat production are simulated in each sub-region using the biophysical Crop Environment REsource Synthesis (CERES) models. These simulations are then combined with the MIKE BASIN hydrologic model for river floods in the Ganges-Brahmaputra-Meghna (GBM) Basins, and the MIKE21 Two-Dimensional Estuary Model to determine coastal inundation under conditions of higher mean sea level. The impacts of each factor depend on GCM configurations, emissions pathways, sub-regions, and particular seasons and crops. Temperature increases generally reduce production across all scenarios. Precipitation changes can have either a positive or a negative impact, with a high degree of uncertainty across GCMs. Carbon dioxide impacts on crop production are positive and depend on the emissions pathway. Increasing river flood areas reduce production in affected sub-regions. Precipitation uncertainties from different GCMs and emissions scenarios are reduced when integrated across the large GBM Basins’ hydrology. Agriculture in Southern Bangladesh is severely affected by sea level rise even when cyclonic surges are not fully considered, with impacts increasing under the higher emissions scenario.  相似文献   

Anticipated economic costs and benefits of ratification of the Kyoto Protocol by the State of Qatar     

Azhari F.M. Ahmed  M. J. Al Maslamani 《Climate Policy》2013,13(1):75-80

Abstract

Further ratification of the Kyoto Protocol by non-Annex 1 countries such as the State of Qatar will not affect the entrance into force of the Treaty; however, ratification remains an important decision due to other considerations, primarily the economic costs and benefits associated with ratification. As a member of the Organization of Petroleum Exporting Countries (OPEC), Qatar's economic position is closely allied with revenue generated from its oil and natural gas resources. Qatar expects adverse impacts from implementing the Kyoto Protocol, though the estimated magnitude varies enormously with different models. Also, the impacts depend significantly on how the implementation is done; for example, the kind of policies that other countries use. Qatar is able to counter adverse impacts by exploiting its greater share of natural gas and developing energy-intensive industries that produce nonenergy goods such as steel, petrochemicals, and chemicals. Furthermore, it is clear that clauses in the Protocol can be developed to protect OPEC interests, and if Qatar does not ratify the Protocol, it will be excluded from the subsequent rule-making processes. On balance, there are benefits to ratifying the Treaty, and there is also a strong need for extensive further research.  相似文献   

K-dV solitons in a magnetized dusty plasma with two distinct temperature nonextensive electrons and Maxwellian ions     

M. Emamuddin  A. A. Mamun 《Astrophysics and Space Science》2014,353(2):507-514

Nonlinear propagation of dust-acoustic (DA) waves in a magnetized dusty plasma, consisting of negatively charged mobile dust, Maxwellian ions and two distinct temperature nonextensive electrons (following nonextensive q-distribution each), has been studied and analyzed by deriving and solving the Korteweg-de-Vries (K-dV) equation. According to the outcomes of the investigation, the basic characteristics of the DA solitary profiles are found to be strongly modified by the external magnetic field, nonextensivity of the electrons and the respective number densities of the two species of electrons. The results of this investigation can be applied in both laboratory and astrophysical plasma scenarios for understanding the basic features of the localized electrostatic dust-acoustic solitary waves (DASWs).  相似文献   

Shear and compressional dust Alfvén solitons in a magnetized plasma medium of opposite polarity dust     

A. A. Mamun 《Astrophysics and Space Science》2014,351(1):173-179

Shear and compressional dust Alfvén solitons propagating in a medium of opposite polarity magnetized dust fluids have been theoretically studied by using the reductive perturbation method. The derivative nonlinear Shrödinger (DNLS) and Korteweg-de Vries (K-dV) equations, and their stationary solitonic solutions have been derived to identify the basic properties of shear and compressional dust Alfvén solitons. It is found that the opposite polarity dust medium under consideration supports the shear and compressional dust Alfvén solitons having new features with new (slow) time and (large) length scales. The basic features (amplitude and width) of the shear dust Alfvén solitons are found to be significantly different from those of the compressional ones. The importance of our results in understanding the nonlinear (localized) electromagnetic wave phenomena in space environments and laboratory devices is briefly discussed.  相似文献   

Hydrogeological aspects of groundwater drainage of the urban areas in Kuwait City     

Muhammad F. Al‐Rashed  Mohsen M. Sherif 《水文研究》2001,15(5):777-795

Residential areas in Kuwait City have witnessed a dramatic rise in subsurface water tables over the last three decades. This water rise phenomenon is attributed mainly to over irrigation practices of private gardens along with leakage from domestic and sewage networks. This paper presents a comprehensive study for urban drainage in two selected areas representing the two hydrogeological settings encountered in Kuwait City. In the first area, a vertical drainage scheme was applied successfully over an area of 1 km². The system has been under continuous operation and monitoring for more than 4 years without problems, providing a permanent solution for the water rise problem in this area. The hydrogeological system has approached steady state conditions and the water levels have dropped to about 3·5 m below the ground surface. In the second area a dual drainage scheme, composing of horizontal and vertical elements, is proposed. Horizontal elements are suggested in the areas where the deep groundwater contains hazardous gases that may pose environmental problems. The proposed drainage scheme in the second area has not yet been implemented. Field tests were conducted to assess the aquifer parameters in both areas and a numerical model has been developed to predict the long‐term response of the hydrogeological system in the two areas under consideration. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

The physics of the galactic halo gas     

I. G. Kovalenko  Yu. A. Shchekinov  Al. A. Suchkov 《Astrophysics and Space Science》1989,152(2):223-238

The available data speak in favour of space and time inhomogeneity of gaseous corona of our Galaxy. The observedCIV and SiIV ions are formed mainly by fast photons and localized inHII-clouds of the galactic halo. On the other hand, theNV ions are thermally ionized and localized in the gas corresponding to a transformation of hot intercloud coronal gas in theHII-clouds. TheHII-clouds exhibit downward the gas flow. The galactic fountain can eject the interstellar matter up to height of 1 kpc. Such ejections may be also displayed inCIV, SiIV, and partiallyNV, and partiallyNV absorptions. But large gaseous corona extending up to 3–5 kpc proves to be mass-unbalanced. It is possible that the existence of corona is evidence for violent star formation in the galactic disc in the recent past.  相似文献   

Curie depth determination from aeromagnetic spectra   总被引：6，自引：0，他引：6  

R. T. Shuey  D. K. Schellinger  A. C. Tripp  L. B. Al 《Geophysical Journal International》1977,50(1):75-101

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基于动态树结构的河网分析方法     

艾自兴  牛瑞芳  毋河海  谌虎 《测绘科学》2006,31(3):80-81

某条河流除了河流自身的数量与质量特征外,该河流在河网结构中的空间位置及其相关结构特征将提供全局性的评价依据。河网的空间形态结构特征由各条河流的几何特征和河流之间的相互关系决定,为了完整表示河网的空间形态结构特征,本文提出了基于动态树结构的河网分析思想,阐述了动态河网树结构的建立、维护及其应用的方法。  相似文献   

A multi-proxy record of the Last Glacial Maximum and last 14,500?years of paleoenvironmental change at Lone Spruce Pond, southwestern Alaska     

Darrell S. Kaufman  Yarrow Axford  R. Scott Anderson  Scott F. Lamoureux  Daniel E. Schindler  Ian R. Walker  Al Werner 《Journal of Paleolimnology》2012,48(1):9-26

Sediment cores from Lone Spruce Pond (60.007°N, 159.143°W), southwestern Alaska, record paleoenvironmental changes during the global Last Glacial Maximum (LGM), and during the last 14,500 calendar years BP (14.5?cal?ka). We analyzed the abundance of organic matter, biogenic silica, carbon, and nitrogen, and the isotope ratios of C and N, magnetic susceptibility, and grain-size distribution of bulk sediment, abundance of alder shrub (Alnus) pollen, and midge (Chironomidae and Chaoboridae) assemblages in a 4.7-m-long sediment sequence from the depocenter at 22?m water depth. The basal unit contains macrofossils dating to 25?C21?cal?ka (the global LGM), and is interpreted as glacial-lacustrine sediment. The open water requires that the outlet of the Ahklun Mountain ice cap had retreated to within 6?km of the range crest. In addition to cladocerans and diatoms, the glacial-lacustrine mud contains chironomids consistent with deep, oligotrophic conditions; several taxa associated with relatively warm conditions are present, suggestive of relative warmth during the global LGM. The glacial-lacustrine unit is separated from the overlying non-glacial lake sediment by a possible disconformity, which might record a readvance of glacier ice. Non-glacial sediment began accumulating around 14.5?cal?ka, with high flux of mineral matter and fluctuating physical and biological properties through the global deglacial period, including a reversal in biogenic-silica (BSi) content during the Younger Dryas (YD). During the global deglacial interval, the ??¹³C values of lake sediment were higher relative to other periods, consistent with low C:N ratios (8), and suggesting a dominant atmospheric CO₂ source of C for phytoplankton. Concentrations of aquatic faunal remains (chironomids and Cladocera) were low throughout the deglacial interval, diversity was low and warm-indicator taxa were absent. Higher production and air temperatures are inferred following the YD, when bulk organic-matter (OM) content (LOI 550?°C) increased substantially and permanently, from 10 to 30?%, a trend paralleled by an increase in C and N abundance, an increase in C:N ratio (to about 12), and a decrease in ??¹³C of sediment. Post-YD warming is marked by a rapid shift in the midge assemblage. Between 8.9 and 8.5?cal?ka, Alnus pollen tripled (25?C75?%), followed by the near-tripling of BSi (7?C19?%) by 8.2?cal?ka, and ??¹⁵N began a steady rise, reflecting the buildup of N and an increase in denitrification in soils. Several chironomid taxa indicative of relatively warm conditions were present throughout the Holocene. Quantitative chironomid-based temperature inferences are complicated by the expansion of Alnus and resulting changes in lake nutrient status and production; these changes were associated with an abrupt increase in cladoceran abundance and persistent shift in the chironomid assemblage. During the last 2,000?years, chironomid-assemblage changes suggest cooler temperatures, and BSi and OM values were generally lower than their maximum Holocene values, with minima during the seventh and eighth centuries, and again during the eighteenth century.  相似文献