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F. Lindenmaier R. Miller J. Fenner G. Christelis H. G. Dill T. Himmelsbach S. Kaufhold C. Lohe M. Quinger F. Schildknecht G. Symons A. Walzer B. van Wyk 《Hydrogeology Journal》2014,22(6):1307-1328
An exploration strategy for groundwater was established and followed in the northern Namibian Cuvelai-Etosha Basin (CEB). The data derived from transient electromagnetics, rotary-drilling, coring and sample investigation were used to refine stratigraphy and hydrostratigraphy, and to develop a 3D map of aquifers within the Cubango Megafan. The results have delineated three major aquifers. The newly found, deep-seated Ohangwena II Aquifer (KOH-2) has the potential of providing significant additional water to the water supply of northern Namibia and Angola. While near-surface aquifers carry predominantly brackish water, freshwater in the deep-seated aquifer is further extended and features good hydraulic properties. To date, only a small part of the hydrogeological potential of arid CEB has been explored and an extension of exploration is needed, including southern Angola. The combination of structural, sedimentological and hydrogeological approaches greatly advanced both the geological and hydrogeological understanding. With regard to the deep-seated aquifer, strict measures need to be applied to ensure that the water in the KOH-2 reservoir is exploited sustainably. Water control areas need to be established to ensure long-term preservation of this newly explored aquifer. 相似文献
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Anna Scolobig Nadejda Komendantova Anthony Patt Charlotte Vinchon Daniel Monfort-Climent Mendy Begoubou-Valerius Paolo Gasparini Angela Di Ruocco 《Natural Hazards》2014,73(3):1523-1545
Technical and institutional capacities are strongly related and must be jointly developed to guarantee effective natural risk governance. Indeed, the available technical solutions and decision support tools influence the development of institutional frameworks and disaster policies. This paper analyses technical and institutional capacities, by providing a comparative evaluation of governance systems in Italy and France. The focus is on two case studies: Naples and Guadeloupe. Both areas are exposed to multiple hazards, including earthquakes, volcanic eruptions, landslides, floods, tsunamis, fires, cyclones, and marine inundations Cascade and conjoint effects such as seismic swarms triggered by volcanic activity have also been taken into account. The research design is based on a documentary analysis of laws and policy documents informed by semi-structured interviews and focus groups with stakeholders at the local level. This leads to the identification of three sets of governance characteristics that cover the key issues of: (1) stakeholders and governance level; (2) decision support tools and mitigation measures; and (3) stakeholder cooperation and communication. The results provide an overview of the similarities and differences as well as the strengths and weaknesses of the governance systems across risks. Both case studies have developed adequate decision support tools for most of the hazards of concern. Warning systems, and the assessment of hazards and exposure are the main strengths. While technical/scientific capacities are very well developed, the main weaknesses involve the interagency communication and cooperation, and the use and dissemination of scientific knowledge when developing policies and practices. The consequences for multi-risk governance are outlined in the discussion. 相似文献
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地浸钻孔是一种以采矿为目的的钻孔,提高钻孔出水量就是提高钻孔的采矿量。通过对多年地浸钻孔施工经验和理论进行分析,发现影响钻孔出水量的主要因素为钻井泥浆的成分和性能以及人工过滤层的渗透性差异,提出在地浸钻孔施工方案中采用植物胶净化泥浆钻进和扩孔、投砾罐射吸式填砾、物理化学组合洗井3种技术措施,对比前后施工钻孔的出水量大小,证明了该技术措施对提高地浸钻孔出水量具有良好的效果。 相似文献
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One of the most important causes of damages after the earthquakes is the soil liquefaction. Liquefaction can be defined as temporary loss in strength of saturated sandy and silty deposits under transient and cyclic loadings due to excess pore water pressure. This study includes determination of liquefaction potential in Erzincan city center and its vicinity. Due to the proximity of the North Anatolian Fault Zone, in a probable earthquake, Erzincan Province is thought to be affected. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes was determined. These earthquake magnitudes were selected as 6.0, 6.5, 7.0, 7.5, respectively. Liquefaction potential was investigated using standard penetration test (SPT) data. The first stage of the study, 63 boreholes in different locations was drilled and SPT was performed. Disturbed and undisturbed soil samples were taken from these boreholes. Laboratory testing was performed to determine physical properties of soil samples, and liquefaction potential analyses were examined using three methods, namely Seed and Idriss (J Soil Mech Found Div ASCE 97(9):1249–1273, 1971), Tokimatsu and Yoshimi (Soil Found 23(4):56–74, 1983), Iwasaki et al. (Soil liquefaction potential evaluation with use of the simplified procedure. International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, pp 209–214, 1981). In order to complete liquefaction analysis within a short time, MATLAB program was prepared. Liquefaction potential analyses were carried out with the MATLAB program. At the final stage of this study, liquefaction potential maps were prepared for different earthquake magnitudes. The expected results will be shared with the local authorities and important engineering remedial measurements will be proposed to prevent further life losses and to mitigate property losses. 相似文献
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在山西三交地区的煤层气井SJSG-01井施工中,依据其钻探任务,采用了常规钻进、空气、空气泡沫、PDC+直螺杆复合钻进、绳索取心钻进技术结合的多工艺钻进技术。一开采用常规三牙轮钻头和普通泥浆钻进,下完表层套管;二开先期采用空气、空气泡沫作为循环介质,利用潜孔锤钻进,在钻遇含水层大量涌水时,采用PDC钻头+直螺杆复合钻进至完钻,在需要取心的井段,采用绳索取心钻进。针对不同钻进技术条件下岩屑录井、钻时录井、气测录井等工作存在的问题,采取了相应的技术措施,并对部分设备进行了改造。通过实践,总结出一套空气和复合钻进条件下的岩屑捞取、气体检测等现场录井方法。 相似文献
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结合工作经验和项目的具体要求,首次组织实施了国家级一孔多层地下水示范监测井的设计和施工项目,并大胆采用了PVC—U塑料管“裸眼四次成井”新工艺。论述了设计思路、具体技术措施和最终取得的成果。 相似文献
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C. Di Salvo M. Moscatelli R. Mazza G. Capelli G. P. Cavinato 《Environmental Earth Sciences》2014,72(7):2279-2299
As established in the European Water Framework Directive, the development of groundwater numerical models is fundamental for adopting water management plans aimed at preserving the water resource and reducing environmental risks. In this paper, authors present a methodology for the estimation of groundwater resource of an alluvial valley, in an urban area characterized by a complex hydrostratigraphic setting and scarcity of hydrogeological data; the study area is the urban and sub-urban area of Rome (Italy). A previous, elaborated hydrostratigraphic model set the base for the development of 3D, steady state, sub-basin scale numerical model, implemented by the finite-difference code MODFLOW 2000®; the water system components were derived by elaboration of available data. The alluvial aquifer of the Tiber River Valley, which runs in the middle of the City in a NNW–SE direction, has been analyzed in detail, since it is covered by a densely populated area hosting most of Rome’s historical heritage, and it is characterized by low quality geotechnical parameters. Results suggest that in areas with high hydrostratigraphic complexity and scarcity of hydrogeological data, a sub-basin scale, and steady-state numerical model can be very helpful to verify the conceptual model and reduce the uncertainty on the water budget components. The proposed steady-state model constitutes the base for future applications of transient state and local scale models, required for sustainable water management. 相似文献
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钻探是水利水电工程勘探中获取地下信息最直接、最重要的手段,钻探质量对水利工程的投资和安全具有极其重大的影响。绳索取心是提高钻探质量十分重要的技术,在国土资源、冶金、煤炭等部门得到了广泛的应用。但是将该技术应用于水利水电工程勘探还存在压水试验、绳索取心钻具不匹配、冲洗液限制等问题。通过对上述问题的分析和研究,提出了解决思路和方法,且在工程实践中取得了良好的效果。特别是研究设计的不提大钻压水试验方法,将压水试验和绳索取心钻进有机地结合在一起,很好地解决了绳索取心钻进难以适应水利水电勘探的关键技术难题。 相似文献
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Uranium mining in southeastern Germany resulted in significant environmental risks. Closure of the mines and subsequent rises of water levels may result in heavy-metal and radionuclide-bearing mine waters penetrating aquifers that are used for water supply. While there are certain (geo-)technical constraints on the schedule with which flooding of the mines can proceed, this process must not result in aggravating the problem of metal release. Evaluation of the likely 'natural' geochemical situation of Königstein mine after mining has ceased, and different scenarios for the release of metals indicates that rapid flooding, albeit avoiding unnecessary aeration of the waters, is likely to result in reducing conditions and consequently low U-solubilities. 相似文献
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I. A. Ostrovsky 《Physics and Chemistry of Minerals》1979,5(2):105-118
The thermodynamic properties of 25 substances (elements, compounds, modifications) are calculated on the basis of an extrapolation of their caloric values and compressibilities into the region of pressures up to 2mbar and temperatures up to 4,000K. The extrapolation methods are described. The ratio of molar volumes is used to predict the thermodynamic properties of the high pressure modifications. It is inferred that water vapour and oxides of Mg, Fe, and Si ought to be stable in the entire mantle. In the lower mantle garnet should be more stable than the perovskite-type phase of MgSiO3 (in presence of Al2O3 or Fe2O3). ‘Perovskite’ phase plus MgO are more stable here than forsterite, Mg2SiO4. Pyrrhotite, FeS, reveals astonishing stability in the entire mantle and in the outer core as well. Carbon dioxide, CO2, may exist only in the upper mantle, whereas methane, CH4, remains stable in the entire mantle. 相似文献
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Sustainable-yield estimation in semi-arid conditions is always challenging, especially for fractured rock aquifers. An approach to assess sustainability is discussed using a case study from rural semi-arid Namibia. The fractured-rock aquifers in the study area have complex configuration. Geology maps, hydrocensus data, geophysical surveys, and drilling and hydraulic testing data were used to produce a conceptual model. Aquifer parameters were estimated based on the hydraulic test data and numerical modelling. Due to lack of data, as is often the case in rural Namibia, the simulation results had to be verified against geological and hydrogeological constraints. It is concluded that the aquifer system is sustained by episodic recharge and the long-term gain in storage (about 3,285 m3/a) represents the maximum extractable volume. It is recommended that the continuous monitoring system for groundwater level, river flow and rainfall should be part of a long-term scheme. The magnitude and frequency of the recharge events and extraction should be monitored in order to sustainably manage the resource. Although the illustrated approach is based on limited data, it provides a basis for management of individual groundwater schemes in semi-arid conditions in sub-Saharan Africa. 相似文献
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Changsheng Xie 《中国地球化学学报》1984,3(2):161-166
This paper reports the use of synergist-impregnated Polyurethane foams for preconcentrating trace thorium from natrual waters. The polyether type Polyurethane foams were employed, which were loaded with bis (2-ethylhexyl) phosphoric acid/tributyl phosphate/carbon tetrachloride (2:5:93, V/V/V) mixture. The surplus reagent was removed by filter paper. The loaded foams prepared in this way were dipped into the water sample and stirred for 20 minutes. The optimum conditions for preconcentration are: samples should be adjusted to about pH 1 and temperature kept within 30°-45°C. The distribution and phase ratios were calculated to be 4.26 x104 and 2.01x104 respectively, assuming that the mixture and water were totally immiscible with each other. The actural values were all slightly greater than the calculated ones. After removing the foam from the sample, the former was washed with water and subjected to wet oxidation with concentrated nitric and perchloric acids. The residue was taken up with dilute hydrochloric acid. The amount of thorium in the water sample was spectrophotometrically determined with Arsenazo III at 665 nm. The method is simple, rapid, accurate and inexpensive. 相似文献
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I. A. Nicholls 《Contributions to Mineralogy and Petrology》1974,45(4):289-316
Pressure-temperature conditions for which “andesitic” liquids (~60% SiO2) may coexist with mineral assemblages of the type magnesian olivine + orthopyroxene + clinopyroxene±amphibole±phlogopite have been investigated, both by means of partial melting experiments on the pyrolite model composition, and by experiments involving addition of olivine to andesite or basaltic andesite compositions at or near their liquidus temperatures. In the latter experiments, reaction relationships between quartz-normative liquid and olivine were made to proceed until olivine persisted. The composition of the final liquid in equilibrium with olivine (plus pyroxenes etc.) was then estimated by microprobe analysis of its quench products (glass, quench crystals). The inferred liquid compositions were tested for equilibrium with coexisting crystals using criteria based on mass balance within the total assemblage, equilibrium element partition relationships, and the requirement that the liquidus temperatures and near-liquidus crystalline phases of these compositions should closely match the temperature of the original olivine-addition experiment and the crystalline phases developed during it. At 1000° C–1050° C, liquids which satisfy these criteria for equilibrium with assemblages which include olivine are “andesitic” (58–60% SiO2, 5–12% normative Qz) only at water pressures ≤ 10kb. At 15 kb, liquids in equilibrium with olivine at 1000° C and 980° C have ~56% SiO2, high alkali contents, and 5–10% normative olivine. Similar compositions are in equilibrium with orthopyroxene and garnet alone at 20 kb. These results show that andesitic magmas are unlikely to be produced by melting of a peridotitic mantle at pressures >10 kb (depths>35 km). If hydrous, but otherwise geochemically primitive peridotitic compositions are partially melted at pressures<10 kb, then “andesitic” products will be much more magnesian and poorer in alkalies than typical natural andesites. These conclusions raise serious difficulties for models of andesite genesis by the melting of hydrous peridotitic mantle immediately overlying Benioff zones. 相似文献
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Polycyclic aromatic hydrocarbons (PAHs) are a group of aromatic hydrocarbons with high toxicity to human health. PAH emissions from industrial activities have become the primary sources of PAH contamination in Chinese watersheds. Here, we analyzed 10 individual priority PAHs in 120 water samples taken from middle reach of Huaihe River, China. The results show that the PAH levels in studied watershed are significantly lower as compared to other Chinese watersheds, approaching or slightly exceeding the PAH levels in watersheds from selected European and North American countries. We observe rather large variation in spatial and vertical PAH distributions, pointing to PAH inputs from local industrial emissions, and PAH cycle among atmosphere, water and sediment. Individual PAH ratios (i.e., phenanthrene/anthracene and fluorene/pyrene) and principal components analysis suggest a primarily pyrolytic PAH sources (combustion of coal and coke) in water column. Other accompanying PAH sources include emissions from steel industry and gasoline. Total toxic benzo[a]pyrene equivalent of PAHs in studied water column indicates that PAHs in watershed of middle reach of Huaihe River pose limited toxicity to the environment. 相似文献