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ABSTRACTThe application of remotely-sensed data for hydrological modeling of the Congo Basin is presented. Satellite-derived data, including TRMM precipitation, are used as inputs to drive the USGS Geospatial Streamflow Model (GeoSFM) to estimate daily river discharge over the basin from 1998 to 2012. Physically-based parameterization was augmented with a spatially-distributed calibration that enables GeoSFM to simulate hydrological processes such as the slowing effect of the Cuvette Centrale. The resulting simulated long-term mean of daily flows and the observed flow at the Kinshasa gauge were comparable (40 631 and 40 638 m3/s respectively), in the 7-year validation period (2004–2010), with no significant bias and a Nash-Sutcliffe model efficiency coefficient of 0.70. Modeled daily flows and aggregated monthly river outflows (compared to historical averages) for additional sites confirm the model reliability in capturing flow timing and seasonality across the basin, but sometimes fails to accurately predict flow magnitude. The results of this model can be useful in research and decision-making contexts and validate the application of satellite-based hydrological models driven for large, data-scarce river systems such as the Congo. 相似文献
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Inequalities are no respecter of countries, including the affluent ones. Nevertheless, these problems appear to prevail more in the developing countries, which have the dubious distinction of having the highest degrees of inequalities in the world. Inequalities exist between urban and rural areas, as well as between the various regions. This paper discusses inequalities in Ghana and Zimbabwe, emphasizing the rural–urban dichotomy. Using data from the Ghana Demographic and Health Surveys (GDHS) and the Zimbabwe Demographic and Health Surveys (ZDHS) conducted by the respective statistical authorities of both countries and Macro International, the paper analyses existing inequalities in both countries. The paper also attempts to elucidate and understand the causes. It concludes that the traditional explanation of disparities that attribute the conditions to aberrations in the operations of market forces, while having some validity, may not provide a full explanation for Ghana and Zimbabwe’s predicament. It argues that whilst the existing disparities may be rooted in history, their persistence and worsening in the post-independence era could only be understood with reference to the corruption, nepotism and the mismanagement that have characterized these states since they gained their independence. 相似文献
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A significant quantity of hydrocarbons (including alkanes) is occluded in the skeleton of the asphaltene molecule. The hydrocarbons are probably remnants of the “original oil” which had been retained within the asphaltene matrix and protected from the secondary alteration processes that occurred subsequently in the oil reservoirs. In this work we report that oxidation of asphaltenes by stirring with 30%H2O2–HAc or NaIO4–NaH2PO4 can release nC7-soluble oxidized products, including the occluded hydrocarbons. Characterization of the nC7-soluble fractions of oxidized products can be applied to highlight some geochemical problems, such as in studies of oil–oil correlation, oil–source correlation and secondary alterations of oil reservoirs. It will be especially useful to recover the original geochemical information of some oil reservoirs heavily degraded by post-depositional processes. 相似文献
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There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation (T1d) marlite in Ni’erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has not been determined to date. Multiple suites of source rocks of different ages exist in the depression. Both the oil seepages and potential source rocks have undergone complicated secondary alterations, which have added to the difficulty of an oil-source correlation. For example, the main source rock, a Lower-Cambrian Niutitang Formation (?1n) mudstone, is over mature, and other potential source rocks, both from the Permian and the Triassic, are still in the oil window. In addition, the T1d oil seepages underwent a large amount of biodegradation. To minimize the influence of biodegradation and thermal maturation, special methods were employed in this oil-source correlation study. These methods included catalytic hydropyrolysis, to release covalently bound biomarkers from the over mature kerogen of ?1n mudstone, sequential extraction, to obtain chloroform bitumen A and chloroform bitumen C from the T1d marlite, and anhydrous pyrolysis, to release pyrolysates from the kerogen of T1d marlite. Using the methods above, the biomarkers and n-alkanes released from the oil samples and source rocks were analysed by GC–MS and GC-C-IRMS. The oil-source correlation indicated that the T1d oil seepage primarily originated from the ?1n mudstone and was partially mixed with oil generated from the T1d marlite. Furthermore, the seepage also demonstrated that the above methods were effective for the complicated oil-source correlation in the Southern Guizhou Depression. 相似文献
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Origin of natural sulphur-bearing immiscible inclusions and H_2S in oolite gas reservoir, Eastern Sichuan 总被引：1，自引：0，他引：1
LIU Dehan XIAO Xianming XIONG Yongqiang GENG Ansong TIAN Hui PENG Ping'an SHEN Jiagui WANG Yunpeng 《中国科学D辑(英文版)》2006,49(3)
Fluid inclusions as captured in homogeneous fluids in rocks and minerals have been extensively studied and successfully applied to exploring the metalloge- netic temperature and pressure of metallic ore deposits and in investigating hydrocarbon generation, migra- tion, etc.[1―6]. In regard to multiple forms of immis- cible inclusions in rocks and minerals, a significant amount of research has already been conducted toward the immiscible inclusions and “boiling” inclusions in CO2-H2O system… 相似文献
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The changing rainy season climatology of mid-Ghana 总被引：1，自引：0，他引：1
Daily rainfall data are examined through the temporal analysis of various definitions of variable temporal units (VTUs) consisting of combinations of various starting dates and durations over mid-Ghana. These VTUs are independent of, yet encompass, the starting dates and durations of the major and minor rainy seasons. Within each VTU, total rainfall and number of rainy days are calculated to describe the rainfall characteristics of the unit. Means and variances of each variable are calculated for each unit over two 20-year periods, 1951–1970 (P1) and 1981–2000 (P2). In P2, the major and minor rainy seasons have undergone varying degrees of desiccation. This reduction in rainfall is, however, not temporally or spatially uniform. The widespread decline of mean rainfall totals and number of rainy days during the minor rainy season, often associated with greater inter-annual variability, is particularly threatening to the production of a second crop. 相似文献
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以济阳坳陷下古生界海相碳酸盐岩作为研究重点,用生烃动力学方法来研究碳酸盐岩生油气过程,对各组分的生烃动力学参数进行标定,并应用热解动力学参数确定海相碳酸盐岩的生烃定量方法.在此基础上进行二次生烃动力学特征和生烃史研究,探讨下古生界碳酸盐岩的生烃潜力.燕山期古地热场具有高地温梯度和高大地热流分布广泛的特征,是古生界二次生... 相似文献
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Pyrolysis kinetics are determined for a series of asphaltene samples associated with different types of kerogens. The activation energy distributions obtained for asphaltenes related to type I kerogens cover a wide range, with significant hydrocarbon generation with activation energies above 350 kJ/mol. The ranges of activation energy distributions are relatively narrow for asphaltenes associated with type II and III kerogens, with little hydrocarbons generated with activation energies above 350 kJ/mol. If the type of associated kerogen can be reasonably constrained, the pyrolysis kinetics of the asphaltenes is potentially a very useful tool for assessing the maturity levels of reservoired oils. The results of pyrolysis kinetics indicate that there is still significant potential for asphaltenes to regenerate hydrocarbons. 相似文献