东、南洞庭湖的径流、泥沙特征及冲淤规律

通过实地调查并对1957年以来水文、泥沙观测资料做系统分析和计算,探讨东、南洞庭湖出、入湖水量、沙量的年际和年内变化特征,以及长江下荆江段裁弯对湖区径流和泥沙的影响。提出了湖区泥沙汛淤枯冲的变化规律及水位升降与湖区泥沙冲淤的关系;论证了丰、平、枯年湖区淤积严重,面积日益缩小对径流的调节作用正在减弱。     

Point and Diffuse Nutrient Emissions and Transports in the Odra Basin and its Main Tributaries

The river Odra is one of the biggest transboundary rivers in Central Europe. The basin is characterized by an area of 110 074 km?sk (upstream Krajnik Dolny) and a population of about 15.5 million inhabitants. Compared with the Westeuropean river basins the specific runoff of the Odra basin is low and amounts only 4.5 L km?sk s–1. The long term changes of the average annual nutrient transport of the Odra at Krajnik Dolny show for the period 1991 to 1994 a low reduction for phosphorus but no changes for nitrogen. For the period of 1991 to 1994 an inventory of the point sources produces emissions of 10.7 kt a–1 P and 54.4 kt a–1 N upstream of the station Krajnik Dolny/Schwedt. Emissions from agricultural land and urban areas represent the main diffuse sources. A range of 68 to 96 kt a–1 N and 3.3 to 3.9 kt a–1 P were estimated for the total diffuse emissions depending on the database and the method of modeling. The emission situation of the river is characterized by a high dominance of point sources in the case of phosphorus (about 73%). For nitrogen the diffuse emissions dominate the total emissions to an amount between 59 and 67%. Compared to the emissions the nutrient transport is low. An average load of 5.1 kt a–1 P and 70.1 kt a–1 N was observed at the station Krajnik Dolny for the period 1991 to 1994. The emission and load situation within the main tributaries of the river Odra is comparable to the whole basin. The big difference between the total emissions and the observed load refers to intensive retention and loss processes within the river system of the Odra.     

秦岭造山带与沉积盆地和结晶基底地震波场及动力学响应

秦岭-大别造山带横贯中国大陆中部,并将我国东部分为南北两部;即华北克拉通和扬子克拉通.在南、北相向运动力系驱动下构成了一个极为复杂的复合、叠加构造带、成矿带和地震活动带.同时导致了该地域异常变化的沉积建造和强烈起伏的结晶基底.然而对它们形成的地球物理边界场响应,岩相和结构的异常变化尚不清晰,特别对盆山之间的耦合响应更缺乏深层动力过程的理解.为此本文通过该区榆林-铜川-涪陵长1000 km剖面的地震探测和研究结果提出：（1）沉积建造厚度变化为4~10 km,结晶基底起伏强烈,幅度可达4~6 km;（2）一系列基底断裂将该区切割为南鄂尔多斯盆地和秦岭北缘前陆盆地、秦岭-大巴造山带和南缘前陆盆地与东北四川盆地,其中前陆盆地为秦岭北渭河盆地和秦岭南通江-万源盆地;（3）秦岭造山带是北部华北克拉通向南推挤、南部扬子克拉通向北推挤下隆升的陆内山体,并构筑了其南、北前陆盆地;（4）秦岭造山带的南、北边界并非是一条边界断层,而应是包括前陆盆地在内的组合界带;（5）秦岭与大巴弧形山系源于同一深部结晶基底,即同根生.这一系列的新认识对深化理解秦岭-大巴造山带形成的深层动力过程和演化机理及厘定扬子克拉通的真实北界具有极为重要的意义.     

Holistic environmental assessment and offshore oil field exploration and production

According to UK Government surveys, concern for the environment is growing. Environmental regulation of the industry is becoming wider in its scope and tougher in its implementation. Various techniques are available to assess how the industry can drive down its environmental impact and comply with environmental regulation. Environmental Assessments (EA) required by European law do not cover the whole life cycle of the project that they are analysing. Life Cycle Analysis (LCA) was developed to assess the environmental loadings of a product, process or activity over its entire life cycle. It was the first technique used in environmental analysis that adopted what was described as a holistic approach. It fails this approach by not assessing accidental emissions or environmental impacts other than those that are direct. Cost Benefit Analysis (CBA) offers the opportunity to value environmental effects and appraise a project on the basis of costs and benefits. Not all environmental effects can be valued and of those that can there is considerable uncertainty in their valuation and occurrence. CBA cannot satisfactorily measure the total environmental risk of a project. Consequently there is a need for a technique that overcomes the failures of project-level EA, LCA and CBA, and assesses total environmental risk. Many organizations such as, the British Medical Association, the European Oilfield Speciality Chemicals Association, the Royal Ministry of Petroleum and Energy (Norway) and Shell Expro now recognize that a holistic approach is an integral part of assessing total risk. The Brent SPAR case study highlights the interdisciplinary nature required of any environmental analysis. Holistic Environmental Assessment is recommended as such an environmental analysis.     

Crustal movement and deformation in Taiwan and its coastal area

Introduction Both Taiwan Island and Chinese mainland belong to Eurasian plate in geological structure. And the nearest distance between Taiwan Island and Fujian Province, which is located on the opposite coast, is only 130 km. Although there are high-precision GPS networks in both Taiwan and Fujian Province, joint GPS measurement cannot be made directly because of the inconvenient contact due to the strait between them. However, the GPS networks arranged on b…     

In-plane and anti-plane strong shaking of soil systems and structures

The concept of in-plane and anti-plane shaking is introduced with a rigid block on a plane surface with Coulomb friction. Using a hypoplastic constitutive relation to model the mechanical behaviour of the soil, numerical solutions for a rigid block on a thin dry or saturated soil layer are obtained. The coupled nature of dynamic problems involving granular materials is shown, i.e. the motion of the block changes the soil state—skeleton stresses and density—which in turn affects the block motion. Motions of the block as well as soil response can be more realistically calculated by the new model. The same constitutive equation is applied to the numerical simulation of the propagation of plane waves in homogeneous and layered level soil deposits induced by a wave coming from below. Experiments with a novel laminar shake box as well as real seismic records from well-documented sites during strong earthquakes are used to verify the adequacy of the hypoplasticity-based numerical model for the prediction of soil response during strong earthquakes. The response of a homogeneous earth dam subjected to in-plane and anti-plane shaking is investigated numerically. In-plane and anti-plane shaking is shown to cause nearly the same spreading of a sand dam under drained conditions, whereas under undrained conditions anti-plane shaking causes stronger spreading of the dam. The dynamic behaviour of a breakwater founded on rockfill and soft clay during the 1995 Kobe earthquake is back-calculated to show the good performance of the proposed numerical model also with a structure. Section 9 deals with buildings on mattresses of densified cohesionless soils or fine-grained soils with granular columns, slopes with ‘hidden’ dams and structures on piles traversing clayey slopes to show the suitability of hypoplasticity-based models for the earthquake-resistant design and safety assessment of geotechnical systems.     

地震数据结构分析与油气预测方法

文中引入了地震资料数据结构的概念并解释了地震数据结构和地震数值之间的不同之处。我们的研究表明:地震数据结构与地层含油气性紧密相关,因此对地质和地球物理工作者精确地从地震资料解释含油层是非常有用的。此项技术可用于勘探开发的任何阶段。此方法已在中国一系列勘探井和开发井上试验,并已被证明是可靠的,试验成功率超过80%。此预测的新方法可应用于:(1)海相、三角州相或非海相的沉积环境;(2)非海相碎屑岩和灰岩岩层的沉积岩以及(3)埋深度从300m到2000m,油层最小厚度为8m(主频为约50周)。关键词:     

流体力与构造应力及其相互关系的探讨

构造应力是地壳构造运动最基本的力源之一, 地下流体及流体力在地壳中普遍存在并对构造运动产生重要影响。 该稿讨论了地下流体、 流体力和构造应力以及它们的概念与作用, 分析了流体力和构造应力的异同点: 构造应力是各种力源在地壳中产生变形而引起的应力的综合力, 流体力是流体存在和活动所产生的各种力的合力, 它们的力源主要来自地球内部, 内涵相互交叉, 大小不同, 但均能产生构造变动。     

The sunspot cycle and solar and lunar daily variations inH

Summary Results of sunspot cycle influence on solar and lunar ranges at a low latitude station, Alibag, outside the equatorial electrojet belt, show that the sunspot cycle association in solar ranges is three times that of the lunar ranges in thed- andj-seasons. This is in general agreement with the earlier results for non-polar latitude stations. The association with sunspot number of individual lunar amplitudes is greatest for lunar semidiurnal harmonic in thej-season. During this season, the sunspot cycle influence on lunar variations is more than that on solar variations, thereby indicating that the lunar current is situated at a level more favourable for sunspot cycle influence than the level of the current associated with solar variations. With the increase in solar activity a shift appears in the times of maxima of semidiurnal lunar variation towards a later lunar hour ine- andj-seasons and in the year.     

Homogeneity and constitution of the earth''s lower mantle and outer core

The lower mantle and outer core of the recent “parametric earth model” (PEM), in which the velocity and density distributions in these regions are both smooth and consistent with the Adams-Williamson equation, are extrapolated to zero pressure using fourth-order finite-strain relations, and the results are compared with recent experimental data on relevant materials. The fourth-order term is found to significantly improve the fits to the model. The lower-mantle velocities are found to be significantly higher than those expected for mixtures of MgO, FeO and SiO₂ of olivine or pyroxene compositions. It is concluded that a slightly denser phase assemblage, with a low FeO content (roughly 5 mole%) is required to explain these results. This Fe content is not significantly different from that in the upper mantle. These results imply that no compositional or thermal constraints on whole-mantle convection can be resolved. The extrapolation of the outer core is well-determined, and the results are consistent with a mixture of Fe and a small proportion of a lighter element.     

Data Analysis and Modeling to Optimize Thermal Treatment Cost and Performance

The objective of in situ thermal treatment is typically to reduce the contaminant mass or average soil concentration below a specified value. Evaluation of whether the objective has been met is usually made by averaging soil concentrations from a limited number of soil samples. Results from several field sites indicate large performance uncertainty using this approach, even when the number of samples is large. We propose a method to estimate average soil concentration by fitting a log normal probability model to thermal mass recovery data. A statistical approach is presented for making termination decisions from mass recovery data, soil sample data, or both for an entire treatment volume or for subregions that explicitly considers estimation uncertainty which is coupled to a stochastic optimization algorithm to identify monitoring strategies to meet objectives with minimum expected cost. Early termination of heating in regions that reach cleanup targets sooner enables operating costs to be reduced while ensuring a high likelihood of meeting remediation objectives. Results for an example problem demonstrate that significant performance improvement and cost reductions can be achieved using this approach.     

Tortoises and hares: dissolution,erosion and isostasy in landscape evolution

Denudation mechanisms differ fundamentally between limestone and silicate rock types, which are subject to very different rate thresholds and enhancers/inhibitors. Silicates are removed largely by erosion, the mechanical entrainment and transport of particles. This is a relatively high energy, and highly episodic, process which occurs only when a minimum threshold ?ow velocity is exceeded; it is inhibited by vegetation cover and favoured by strongly seasonal runoff. Limestone is removed largely by chemical dissolution at a rate directly proportional to runoff. Dissolution is a relatively low energy process that can occur at any ?ow velocity or in static water; in general it is enhanced by vegetation cover and non‐seasonality of runoff. These contrasting factors in the denudation of silicates versus limestone can produce strikingly uneven rates of surface lowering across a landscape, sometimes akin to the well known ‘tortoise and hare race’, where the slow and steady denudation of limestones may in the long term exceed the sometimes rapid, but often localized and episodic, erosion of silicates. Prolonged exposure of limestone to a humid temperate climate in a tectonically stable environment produces low‐relief corrosion plains in which limestone uplands are anomalous and, in most instances, due to recent unroo?ng from beneath a siliciclastic cover. In a highly seasonal or semi‐arid climate almost the exact inverse may develop, with ‘?ashy’ runoff and sparse vegetation favouring erosion rather than dissolution. Even under a constant humid climate progressive unroo?ng of a thick limestone unit within folded siliciclastics may lead to a topographic inversion over time, with the limestone outcrop always forming a topographic low ?anked by siliciclastic uplands. Valleys will be initiated on anticlinal crests, where the limestone is ?rst unroofed, but progressive lowering of the limestone causes these valleys to migrate to their ?nal position in the synclinal troughs. In humid climates isostatic compensation in response to slow, but continuous, denudation of extensive limestone outcrops may be a signi?cant factor in the development of relief on adjacent, more slowly eroding, silicate outcrops. Copyright © 2004 John Wiley & Sons, Ltd.     

Ionospheric and Solar Wind Variation during Magnetic Storm Onset and Main Phase at Low- and Mid-latitudes

The relationship between the F2-layer critical frequency and solar wind parameters during magnetic storm sudden commencement (SSC) and main phase periods for intense (IS) and very intense (VIS) class of storms is investigated. The analysis covers low- and mid-latitude stations. The effects of ionospheric storm during SSC period is insignificant compared to the main phase, but can trigger the latter. The main phase is characterized by severe negative storm effect at both latitudes during VIS periods while it is latitudinal symmetric for IS observations. The IS reveal positive/negative storm phase in the low-/mid-latitudes, respectively. Ionization density effect is more prominent during VIS events, and is attributed to large energetic particle and solar activity input into the earth magnetosphere. However, ionospheric effect is more significant at the low-latitude than at the mid-latitude. Lastly, ionospheric storm effect during a geomagnetic storm may be related to the combinational effect of interplanetary and geomagnetic parameters and internal ionospheric effect, not necessarily the solar wind alone.     

Nonlinearities and Linearities in Internal Gravity Waves of the Atmosphere and Oceans

The spectrum of internal gravity waves in the atmosphere and oceans is sufficiently intense that nonlinear interactions must occur, if these waves are analyzed in Eulerian coordinates as is usually done. As it happens, however, if these waves are analyzed in Lagrangian coordinates the most important nonlinearity can be entirely avoided: it is an Eulerian mathematical construct only, not a physical process. The mathematical basis for this assertion is developed here, and some of its consequences are discussed. Among the latter is a questioning of the validity of standard Eulerian eikonal methods of calculating ray paths and related functions in a multiwave environment, discussed in an appendix.     

Estimating temperature and salinity profiles using empirical orthogonal functions and clustering on historical measurements

Oceanographic climatology is normally estimated by dividing the world’s oceans into geographical boxes of fixed shape and size, where each box is represented by a climatological salinity and temperature profile. The climatological profile is typically an average of historical measurements from that region. Since an arbitrarily chosen box may contain different types of water masses both in space and time, an averaged profile may be a statistically improbable or even non-physical representation. This paper proposes a new approach that employs empirical orthogonal functions in combination with a clustering technique to divide the world’s oceans into climatological regions. Each region is represented by a cluster that is determined by minimising the variance of the state variables within each cluster. All profiles contained in a cluster are statistically similar to each other and statistically different from profiles in other clusters. Each cluster is then represented by mean temperature and salinity profiles and a mean position. Methods for estimating climatological profiles from the cluster information are examined, and their performances are compared to a conventional method of estimating climatology. The comparisons show that the new methods outperform conventional methods and are particularly effective in areas where oceanographic fronts are present.     

Mesoscale energetics and flows induced by sea-land and mountain-valley contrasts

We study the relative importance of sea-land and mountain-valley thermal contrasts in determining the development of thermally forced mesoscale circulations (TFMCs) over a mountainous peninsula. We first analyse the energetics of the problem, and using this theory, we interprete the numerical simulations over Calabria, a mountainous peninsula in southern Italy. The CSU 3-D nonlinear numerical model is utilised to simulate the dynamics and the thermodynamics of the atmospheric fields over Calabria. Results show the importance of orography in determining the pattern of the flow and the local climate in a region as complex as Calabria. Analysis of the results shows that the energetics due to the sea-land interactions are more efficient when the peninsula is flat. The importance of the energy due to the sea-land decreases as the mountain height of the peninsula increases. The energy stored over the mountain gains in importance, untill it is released by the readjustment of the warm mountain air as it prevails over the energy released by the inland penetration of the sea breeze front. For instance, our results show that over a peninsula 100 km wide the energy over the mountain and the energy in the sea-land contrast are of the same order when the height of the mountain is about 700 m, for a 1500 m convective boundary layer (CBL) depth. Over the Calabrian peninsula, the energy released by the hot air in the CBL of the mountain prevails over the energy released by the inland penetration of the sea air. Calabria is about 1500 m high and about 50 km wide, and the CBL is of the order of 1500 m. The energy over the mountain is about four time larger than the energy contained in the sea-land contrast. Furthermore, the energetics increase with the patch width of the peninsula, and when its half width is much less than the Rossby radius, the MAPE of the sea breeze is negligible. When its half width is much larger than the Rossby radius, the breezes from the two opposing coastlines do not interact. Over Calabria peninsula, numerical simulations show that the flow is highly ageostrophic, and that the flow intensity increases from sunrise to reach its maximum in the afternoon but before sunset, which suggests that, in the late part of the day, the conversion of potential energy into kinetic energy is balanced by the dissipation.     

Deformation and paleomagnetism

We may use tectonic structures to confirm the primary age of a paleomagnetic remanence component but only if we know how to undo the natural strain history. It is normally insufficient to untilt fold limbs, as in the original version of Graham's Fold Test. One may need to remove also the bulk or local strain and account for strain heterogeneities, achieved by grain-strain and the more elusive intergranular flow. Most important, one must know the sequence of strains and tilts that occurred through geological history because the order of these noncommutative events critically affects the final orientation of the remanence component.In many non-metamorphic rocks, strain-rotation of a remanence component approximates a simple formula, although the actual rotation mechanism is complex. This simple, passive line approximation is confirmed experimentally for strains up to 45% oblate shortening. The passive line hypothesis has permitted successful paleomagnetic restorations in several natural case studies.Experimental deformation of samples with multicomponent remanences shows that differential stresses above a threshold value near 25 MPa selectively remove components with coercivities <25mT, due to domain wall rearrangements in large multidomain magnetite grains. Higher coercivity components are less reduced so that the net remanence vector spins always toward the high-coercivity component, at rates and along paths not predicted by any structural geological formula. Experimentally deformed samples with very fine hematite in the matrix showed their net remanence spinning away from the high coercivity component. This is due to easier mechanical disorientation of the very fine hematite grains, scattering their magnetic moments more and reducing their contribution to the overall remanence. Thus, muticomponent remanences have their components selected for survival based on rock-magnetic and microstructural criteria. Such stress-rotation by coercivity selection does not depend on the orientations of the principal stresses or strains, a concept that is counterintuitive to conventional structural geology.Syn-tectonic remagnetization is common in deformed sedimentary sequences and laboratory experiments reveal that a only moderate differential stress remagnetization is required to add components parallel to the ambient field, without significant strain. Alternating field demagnetization isolates components smeared along the great circle between the initial remanence direction and the remagnetizing field direction. In this case, the principal directions of the stress and finite strain tensors are irrelevant; remagnetization is triggered by a threshold differential stress. The final remanence direction is controlled by the ambient field direction and the remagnetization path lies along a great circle between the ambient field and the initial remanence direction.     

Satellite and surface geophysical expression of anomalous crustal structure in Kentucky and Tennessee

An equivalent layer magnetization model obtained from inversion of long-wavelength satellite magnetic anomaly data indicates a very magnetic source region centered in south central Kentucky. The magnetization maximum nearly coincides with a gravity high elongated north-south and extending into Tennessee. Previous refraction profiles suggest that the source of the gravity anomaly is a large mass of rock occupying much of the crustal thickness. The outline of the source delineated by gravity contours is also discernible in aeromagnetic anomaly patterns. Taken together, the geophysical data suggest a large, localized mass of intracrustal rock which is both dense and very magnetic. A simple magnetization/density model is given which accounts for the gravity and long-wavelength aeromagnetic anomalies due to the body. We interpret it as a mafic plutonic complex, and several lines of evidence are consistent with a rift association. The body is, however, clearly related to the inferred position of the Grenville Front. It is bounded on the north by the fault zones of the 38th Parallel Lineament. The inferred mean magnetization (4 A/m) of the body is large, but not inconsistent with values reported by others for deep crustal bodies associated with long-wavelength magnetic anomalies. Such magnetization levels can be achieved with magnetic mineralogies produced by normal oxidation and metamorphic processes and enhanced by viscous build-up, especially in mafic rocks of alkaline character.