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1.
An extension to the DRASTIC model is proposed in order to assess aquifer vulnerability to pollution. In contrast to the DRASTIC
model, which considers the unsaturated and saturated zones together and computes a global intrinsic vulnerability index, the
suggested approach discriminates between the aquifer vertical vulnerability (a concept related to the pollutant percolation)
and the groundwater susceptibility (a concept that depends on the behaviour and uses of the groundwater). This approach is
applied to the Haouz aquifer (Morocco) that supplies water to the Marrakech area. This aquifer is widely overexploited and
there is evidence that the groundwater quality is threatened by various sources of pollution. Evaluation of the vertical vulnerability
indicates that the aquifer mainly presents a moderate-to-weak vertical vulnerability. The zones potentially most favourable
to pollutant percolation are mainly located in Central Haouz, along or near the surface wadis. The aquifer susceptibility
is high in places located near the N’Fis, Baaja and Issil wadis. Everywhere else, low-to-moderate susceptibility is observed.
This new approach therefore enables areas of vertical vulnerability and areas of susceptibility to be delineated separately.
As a result, it constitutes a valuable decision-making tool for optimising the management of aquifer water resources and land-use
planning. 相似文献
2.
鉴于大陆岩浆弧上盘广泛分布有碳酸盐岩,岩体上升侵位过程使其碳通量明显的高于洋内岛弧,从而有可能影响着地质历史长时间尺度(百万年)的气候变化。陆弧碳的排放可分为两部分,一部分是与喷出岩相关的火山作用,另一部分是与侵入岩相关的脱碳过程。侵入岩的体量一般是喷出岩体量的10倍以上,由此与侵入岩有关的脱碳作用释放的碳通量不可忽视,可能类似与喷出岩有关的火山作用释放的碳通量甚至更大。火山作用能够将气体直接排入大气中,因此在以往的工作中研究较为充分。但与侵入岩相关的脱碳过程如:矽卡岩化,发生在地下,关于地下脱碳过程如何将碳释放到大气中还缺少详细的工作。本文,通过对比研究火山地区和非火山地区与侵入岩相关的深部脱碳过程,发现深部碳可以通过区域断层系统、地下水系统和热泉、火山通道、隐爆角砾岩筒、高频率的岩浆热液事件等途径瞬时地释放进入大气。通过初步估算,发现单个矽卡岩矿化事件所产生的二氧化碳通量(0.02~0.2Mt/yr)能够与目前地球绝大部分的普通单个火山的碳通量(<0.5Mt/yr)类比。因此岩浆深部脱碳过程对大气的影响至少与火山相当,其对气候的影响不可忽视。 相似文献
3.
Nutrient loading to estuaries with heavily populated watersheds can have profound ecological consequences. In evaluating policy
options for managing nitrogen (N), it is helpful to understand current and historic spatial loading patterns to the system.
We modeled N inputs to Narragansett Bay from 1850 to 2000, using data on population, human waste disposal, livestock, fertilizer,
and atmospheric deposition. We found that total N loading to the bay increased 250% from 1850 to 2000, and 80% from 1900 to
2000. Loading to the upper bay increased far more than that to the lower bay, and the most important source shifted from non-point
animal waste to human waste concentrated at sewage treatment facilities. We also modeled future N loads in 2015 under four
management scenarios. Planned improvements in sewage treatment would reduce N loads 9% below business-as-usual, to the 1990
loading rate. Greater reductions, to circa 1900 rates of loading, may be possible. 相似文献
4.
Nowadays, environmental problems related to soil pollution with heavy metals are numerous, therefore, it is important to understand metals behaviour in aquatic sediments and soils and to estimate their transfer. The fate of metals in the environment is closely related to their interactions with the major reactive compartments (organic matter, iron and manganese oxides, clays). The objective of this work is to develop an approach based on the combination of several models to study metal ion speciation in different environmental systems. Models used to describe the interactions of metals with the main reactive phases in the soil are CD-MUSIC (amorphous and crystallized iron oxides), NICA-Donnan (organic matter and manganese oxides) and cationic ion exchange model (clays). First, this work implies the definition of generic parameters to describe the interactions of the studied metals with iron and manganese oxides and part of this information is missing in the literature. Then, after a validation of the approach by comparison with analytical results, this multi-surface model is applied to test sites corresponding to one soil and two riverine environments.These new models give good predictions of the behaviour of major and trace metal ions even in heterogeneous systems characteristic of natural environment. The measured free metal concentrations in the solution are in agreement with those obtained from model calculations. In the case of the soil test site, the soil solution composition and speciation are predicted using the soil major constituents characteristics. 相似文献
5.
水平定向钻进地层适应性的评价方法 总被引：1，自引：0，他引：1
水平定向钻进的地层适应性对施工技术方案、钻具选择、参数选取和施工效益都有着重要影响。应采用钻进地层的岩土硬度、完整性和研磨性三方面指标,对比钻进技术工艺和技术器具特点,对钻进效率、钻孔的成孔和孔壁稳定性、以及钻具寿命等进行定性及定量的评价,从而有利于大大提高水平定向钻进铺管施工的技术和经济效益。 相似文献
6.
浅层地下水人工回灌应用于上海市工程性地面沉降防治的试验研究 总被引：1，自引：0，他引：1
上海地面沉降主要由过量开采地下水资源和大规模工程建设等因素共同影响,工程性地面沉降引起的地面沉降漏斗严重影响了周边地区生命线工程的建设及运营安全。通过开展试验研究,将深部承压含水层中应用成熟的地下水人工回灌技术引入浅部含水层中,但由于浅部含水层砂层结构及水动力条件与深部含水层差异较大,回灌工艺及方法也存在差异。本次试验工作中,改进了地下水人工回灌工艺流程,并通过同步地面形变监测分析了浅层地下水人工回灌对控制地面沉降的作用效果。结合上海地区实际地层特征以及各种回灌工艺的实际效果,评价了浅层地下水人工回灌技术在防治工程型地面沉降中推广应用的可行性及适用性。 相似文献
7.
Eustace D'Souza 《GeoJournal》1994,34(2):207-211
The protection and restoration of the environment is the responsibility of all. With the end of the Cold War a new reality takes place and gains ground in ever more parts of the world. Troops are returning to peace time locations. Why not use the Military, to some appropriate degree, for this region-stabilizing task? The Military are fully qualified and equipped to do so, and their use is enhanced by their mobility, communications, and administrative self sufficiency. This paper shows, what has been done, is being done, and can be done, based on the experience of the Indian Army, regarded globally as a role model. 相似文献
8.
一个企业要发展,必须要有自己的人力资源优势。而吸引优秀的人力资源,必须建立以人为本的人力资源管理政策,一个优秀企业应从职业生涯规划、员工培训与发展、绩效考评、薪酬激励、关注心理需求等五个与员工切身利益方面进行规划以此增强企业的凝聚力。 相似文献
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10.
Deforestation has been a major cause of climate change and other environmental problems. An accurate estimation of the volume of deforested area is needed for United Nations Reducing Emissions from Deforestation and Forest Degradation (UN-REDD+) policies implementation and global carbon accounting. Accurate information about three-dimensional (3-D) structure of forests is required to quantify forest carbon stock. This study demonstrates the use of different digital elevation models (DEMs) to monitor changes in height due to deforestation in Cambodia to support climate change mitigation policies of UN-REDD+. The Shuttle Radar Topographic Mission-DEM (SRTM-DEM), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER-GDEM) and Panchromatic Remote sensing Instrument for Stereo Mapping-Digital Surface Model (PRISM-DSM) data were calibrated using Ice Cloud and land Elevation Satellite Geoscience Laser Altimeter System (ICESat–GLAS) data. The results obtained from this study clearly indicate the changes in the height of forests due to deforestation activity. The height of cutover forest generated from the PRISM-DSM and SRTM-DEM is more reliable than that from the PRISM-DSM and ASTER-GDEM data. Field data has also been used to validate the height of the cutover forests, which shows ±5 m uncertainties in the estimation. 相似文献
11.
John A. Knox 《Mathematical Geology》2000,32(2):203-215
The Fahrenheit-to-Celsius temperature-conversion equation is a basic component of many introductory earth science courses. Despite its simplicity, it presents a challenge to students and instructors alike because residents of the United States are unfamiliar with the Celsius scale. By solving for the point at which these two temperature scales are equal, it is possible to use the equations for temperature conversion as a springboard to more advanced topics. It is demonstrated that temperature-conversion equations and chaotic equations can be solved using identical numerical and graphical techniques. As a result, the fundamental concepts of chaos theory and numerical methods can be introduced to students in the context of the simplest equations in the earth sciences. These solution methods are applied to the quantitative theory of the extratropical cyclone as an example of the utility and broad scope of this educational approach. 相似文献
12.
13.
14.
A multi-resolution workflow to generate high-resolution models constrained to dynamic data 总被引：2，自引：0，他引：2
Céline Scheidt Jef Caers Yuguang Chen Louis J. Durlofsky 《Computational Geosciences》2011,15(3):545-563
Distance-based stochastic techniques have recently emerged in the context of ensemble modeling, in particular for history
matching, model selection and uncertainty quantification. Starting with an initial ensemble of realizations, a distance between
any two models is defined. This distance is defined such that the objective of the study is incorporated into the geological
modeling process, thereby potentially enhancing the efficacy of the overall workflow. If the intent is to create new models
that are constrained to dynamic data (history matching), the calculation of the distance requires flow simulation for each
model in the initial ensemble. This can be very time consuming, especially for high-resolution models. In this paper, we present
a multi-resolution framework for ensemble modeling. A distance-based procedure is employed, with emphasis on the rapid construction
of multiple models that have improved dynamic data conditioning. Our intent is to construct new high-resolution models constrained
to dynamic data, while performing most of the flow simulations only on upscaled models. An error modeling procedure is introduced
into the distance calculations to account for potential errors in the upscaling. Based on a few fine-scale flow simulations,
the upscaling error is estimated for each model using a clustering technique. We demonstrate the efficiency of the method
on two examples, one where the upscaling error is small, and another where the upscaling error is significant. Results show
that the error modeling procedure can accurately capture the error in upscaling, and can thus reproduce the fine-scale flow
behavior from coarse-scale simulations with sufficient accuracy (in terms of uncertainty predictions). As a consequence, an
ensemble of high-resolution models, which are constrained to dynamic data, can be obtained, but with a minimum of flow simulations
at the fine scale. 相似文献
15.
16.
G. R. Adhikari A. I. Theresraj R. N. Gupta 《Fragblast: International Journal for Blasting and Fragmentation》2004,8(1):41-49
The safety and stability of concrete and masonry dams is a great concern when blasting has to be conducted close to these dams in order to construct small hydro-electric projects. There is a danger of ground vibration amplification to those residential-type buildings that are built close to these dams.
Responses of three concrete and masonry dams were measured directly by conducting a number of blasts and by monitoring vibration in the ground as well as on the dams. The amplitudes and frequencies of the motions were analysed and vibration attenuation relations were derived. These relations were used to compare the vibration levels on the dams with those in the ground.
Because of close-in construction blasts that produced high frequency ground vibrations, there was no amplification of the ground vibrations by these dams. The measured amplitudes of ground vibration were comparable to those of the dams. 相似文献
Responses of three concrete and masonry dams were measured directly by conducting a number of blasts and by monitoring vibration in the ground as well as on the dams. The amplitudes and frequencies of the motions were analysed and vibration attenuation relations were derived. These relations were used to compare the vibration levels on the dams with those in the ground.
Because of close-in construction blasts that produced high frequency ground vibrations, there was no amplification of the ground vibrations by these dams. The measured amplitudes of ground vibration were comparable to those of the dams. 相似文献
17.
H. -W. Wehling Dr. 《GeoJournal》1979,3(1):69-80
Conclusion As all the political and economic changes of the fifth continent Australia's approach to Asia is a gradual process. With the
political recognition of the People's Republic of China Australia gave up its strict anticommunist attitude, regarding its
alliances with the USA as of secondary importance to its future policies and trying to find its own political position. The
political approach to Asia was accompanied by an economic one after Britain's entry into the EEC that caused a restraint on
trade for Australian products on the British market. The intensive relationship with the highly industrialized Japan gave
remarkable impulses to the economic develoment of Australia; the trade relations to the other countries of Asia, especially
to those of South-East Asia, were expanded.
An enlarged foreign trade with these countries, however, requires the establishment and expansion of the native industries
and markets as well as their organisation and the stabilization of their financial powers to enable them to export products
important to Australia and to receive Australian exports of high value on normal terms. So not only humanitarian and political
reasons but sturdy economic interests are at the bottom of Australia's economic and technical aid given to these countries.
Although Australia's approach to Asia still excludes a change of its immigration regulations for the time being it can already
be regarded as efficient. By this approach Australia aims, in its own interest, at the political stability of South-East Asia
and the Pacific and at the economic development of the countries in this region. 相似文献
18.
Nitrogen loads to estuaries: Using loading models to assess the effectiveness of management options to restore estuarine water quality 总被引：1，自引：0，他引：1
Nitrogen (N) loading to estuaries has become a major concern for coastal planners. As urban development on coastal watershed
continues, estuaries and bays are becoming more eutrophic, and cascading effects are being felt at every trophic level. Managers
and stakeholders need to have a suite of effective management tools that can be applied to coastal watersheds to minimize
the effects of eutrophication. We applied an N loading model and an estuarine loading model to examine the effectiveness of
a suite of potential management options that could be implemented in Waquoit Bay, Cape Cod, Massachusetts. This estuarine
system is a case study in which we can explore the relative potential effectiveness of decreasing inputs from wastewater and
fertilizer-derived N, diverting nitrogenous runoff from impervious surfaces, altering zoning ordinances, preserving forested
tracts of land as well as freshwater and saltwater wetlands, harvesting macroalgae, dredging estuary channels, and exterminating
waterfowl. From a combination of simulation results, assessment of the magnitude of loads from different sources, and through
different land covers, and the additional consideration of feasibility we identified management options with high, intermediate,
and low potential effectiveness. Improvement of septic system performance, use of zoning regulations, preservation of forested
tracts and freshwater bodies, and conservation of salt marshes emerged as the most promising avenues to manage N loads in
our system. Installation of wastewater treatment plants, controlling fertilizer use, and harvesting macroalgae would potentially
have intermediate success. Diversion of runoff from impervious surfaces, dredging, and extermination of waterfowl show little
promise at reducing N loads. These conclusions potentially set priorities for decision-makers charged with the management
of Waquoit Bay. The same procedures applied to another watershed-estuary system with different land covers and different estuarine
features may differ. Evaluation studies like this need to be done for any particular site, since the watershed-estuary coupling
and the loads delivered to the receiving estuary could differ. The Waquoit Bay case study provides an example of a protocol
that leads to identification of the most promising management options. 相似文献
19.
竖向圆形荷载作用下弹性半空间问题的位移和应力解是桩基分析的基础。利用Hankel积分变换,首先导出了弹性地基半空间位移与应力的积分形式的通解。通过适当地引入边界条件和界面位移和应力的连续条件,求得了内部作用竖向圆形荷载时弹性地基半空间位移与应力的积分形式解。在此基础上,给出了不同深度处荷载作用投影范围内竖向位移和竖向正应力的平均值。数值结果验证了解析解的正确性。 相似文献
20.
An analytical study to evaluate quantitatively weak zoning of a garnet from a high-grade kinzigite has been performed with an electron microprobe. The technique consists of the reconstruction of a profile step-by-step by successive analyses performed during relatively long counting times (30 s), along a radial profile of 2,500 μm length. The successive analytical data along this profile are statistically treated by Fisher's test and compared with the χ2 values (Pearson's law). These statistical tests were applied to assess microprobe stability and analysis homogeneity, and as a consequence to assure high credibility of the radial variations of the garnet. From core to rim, and for each element, zoning appears as the radial juxtaposition of stationary Poissonian samples. These samples being associated, the garnet appears to be constituted of successive concentric domains with stationary compositions. Different substitutions between Mg, Fe, Mn and Ca are evidenced. Such an analytical approach to chemical zoning can be useful for understanding growth mechanisms, and the possible diffusion reactions with the environment at each growth step. In addition, such a procedure can be used to evaluate accurately the fluid content of cordierite, and to appreciate the nature of the fluids concerned. As an example, the fluid content of a cordierite from a similar high-grade kinzigite has been evaluated. 相似文献