多普勒雷达风场反演技术在西南涡暴雨过程中的应用

利用多普勒天气雷达四维变分同化方法反演了2010和2013年重庆市两次西南涡内的局地强降水不同高度水平风场,分析了易发生局地强降水区域的局地环流特征。结果表明:风场反演能较准确地给出低空急流、低层辐合和局地气旋性涡旋的位置及演变情况,辐合线演变及低空急流的强度和移向对强降水有指示意义;局地气旋性涡旋越深厚,局地强降水的强度和范围越大;不同高度的气旋性涡旋耦合,可能有利于急流的加强和水汽输送。     

广西大明山钨矿区成矿时代及其找矿前景分析

本文选择广西大明山钨矿区含矿石英脉中的辉钼矿和马岭矿区钻孔岩心中辉钼矿进行了ＲｅＯｓ法     

基于WASP模型的太湖流域上游茅山地区典型乡村流域水质模拟

池塘、河渠、水库是乡村流域水环境的重要组成.基于WASP模型,综合运用现场调查、GIS空间分析、污染负荷估算等方法,构建茅山地区李塔陈庄乡村流域的水质模拟模型.结果表明,主要水质指标的污染程度从高至低依次为总氮(TN)、总磷(TP)和高锰酸盐指数、氨氮.TN全年在不同水体中达到劣Ⅴ类的比例在52%~100%,而池塘、河渠的污染程度较为接近.夏、冬季,超过TP劣Ⅴ类限值的河渠占2%~6%,池塘占8%~14%,而流域中部乡村周边的池塘明显更为严重.负荷输入是模型主要不确定性因素,细化种植模式能够提高总体模拟效果,而禽畜散养与农村生活造成的污染则分别对池塘、河渠的水质影响更为明显.本研究建立了乡村流域多种水体在面源污染影响下的水质联系,能够为乡村水环境治理提供决策参考.     

塔里木河中游典型绿洲盐渍化土壤的反射光谱特征

研究盐渍化土壤的光谱特性是利用遥感技术实现在区域尺度上进行土壤盐渍化监测和评价的工作基础, 是建立地面数据和遥感数据关系的桥梁。本文以塔里木河中游典型绿洲--渭干河-库车河三角洲绿洲为研究对象, 采用光谱学技术以及多元统计相结合的方法, 研究干旱区典型绿洲盐渍化土壤的反射光谱特征。首先, 对光谱数据进行预处理(去噪、剔除水分吸收波段), 以便消除仪器本身噪声及外界条件的影响, 并且计算了部分盐渍地样本的光谱吸收特征参数, 说明相同程度的盐渍化土壤具有相似的吸收特征;其次, 研究盐渍化土壤的反射光谱与盐分因子(八大离子、电导率(EC)、含盐量(salt content)、pH、总溶解固体(TDS)等) 之间的关系, 并选择具有代表性的盐分因子与野外实测光谱数据建立定量回归模型, 通过多元线性回归分析得出含盐量、SO₄^2-、TDS、EC与原始光谱数据的相关性分别是0.746、0.908、0.798 和0.933, 达到了理想的效果。本研究对于干旱区典型绿洲盐渍土的光谱特征研究有着重要指示意义, 为发展和完善中国盐渍土理化特征的可见光-近红外反射光谱分析理论奠定科学积累, 并进一步为干旱区土壤盐渍化、沙漠化灾害等环境恶化问题的解决提供新的科学技术手段。     

论我国“1:1万数字高程模型的更新与建库”

结合生产实验对ＤＥＭ的数据源、数据精度与质量控制、数据采集的技术与策略、空间分辨率、地形建模、产品分类和数据组织等方面进行全面的讨论,以期为推进有关工作的进一步完善和在全国实施“１１万数字高程模型的更新与建库”方案提供理论与技术支持     

基于纵波地震和四分量地震的弹性波阻抗反演

为了更好地揭示崖13-1气田的泥岩夹层及剩余气分布,提高采收率,尝试了基于纵波地震和四分量地震的弹性波阻抗反演。利用常规纵波地震资料对崖13-1气田气层进行了多角度同时反演;利用四分量地震资料进行了纵波和转换横波波阻抗反演。基于常规纵波地震资料的弹性波阻抗反演剖面的分辨率较高,气层纵波波阻抗与盖层的纵波波阻抗差异大于横波,但横波波阻抗分辨率比纵波波阻抗高,对气层细节反映得更清楚。利用弹性波阻抗反演结果可以较好地发现剩余气、泥岩夹层及气水界面。转换横波地震资料的分辨率较低,基于四分量地震资料的弹性波阻抗反演的分辨率也比较低。     

Integrated gravity and magnetic study on patterns of petroleum basin occurrence in the China seas and adjacent areas

The China seas and adjacent areas contain numerous petroleum basins. One of the main challenges for future oil and gas exploration is to identify the inherent patterns of petroleum basin distribution. The formation and evolution of petroleum basins along with the migration and accumulation of oil and gas are often closely related to the tectonic environment. The gravity and magnetic fields with high lateral resolution and wide coverage provide important data for regional tectonic research. Based on the gravity data in the Global Satellite Gravity Anomaly Database (V31.1) and magnetic data from the Earth Magnetic Anomaly Grid (2-arc-minute resolution) (V2), this study uses integrated gravity and magnetic field technique to obtain integrated gravity and magnetic field result for the China seas and adjacent areas, and then adopts the normalized vertical derivative of the total horizontal derivative technique to conduct partition. Finally, it identifies the relationship between the partition characteristics and tectonics as well as the patterns of petroleum basin occurrence. The research shows that the partition of gravity and magnetic field integrated result has a good correlation with the Neo-Cathaysian tectonic system and tectonic units. The petroleum basins are characterized according to three blocks arranged from north to south and four zones arranged from east to west. The north?south block structure causes the uneven distribution of oil and gas resources in the mainland area and the differences in the hydrocarbon-bearing strata. Petroleum basins are more abundant in the north than in the south. The ages of the main oil- and gas-bearing strata are “Paleozoic–Mesozoic, Paleozoic–Mesozoic–Cenozoic, and Paleozoic–Mesozoic”, in order from north to south. The difference in the overall type of oil and gas resources in all basins is controlled by the east–west zonation. From east to west, the oil and gas resource type exhibits a wave-like pattern of “oil and gas, gas, oil and gas, gas”. The vertical distribution is characterized by an upper oil (Mesozoic–Cenozoic) and lower gas (Mesozoic–Paleozoic) structure. Within the study area, the Paleozoic marine strata should be the main strata of future natural gas exploration.     

Study of substrate and physico-chemical base classification of the rivers of Nepal

The rivers in Nepal are classified in terms of geographical regions but a more scientific classification such as on the ba-sis of morphology is clearly lacking. This study was done in 9 rivers namely Jhikhukhola of the Koshi system, Aandhikhola, Arungkhola, East Rapti, Karrakhola, Seti and main channel Narayani of the Gandaki system, and two independent systems within Nepal, Bagmati and Tinau. Among the morphologies, river bed or the substratum was taken as the main variable for the analysis which was categ...     

A general Lagrangian tracking methodology for riverine flow and transport

This article presents a new public domain tool for generalized Lagrangian particle tracking in rivers. The approach can be applied with a variety of two- and three-dimensional flow solvers. Particle advection by the flow is incorporated using flow fields from the chosen solver assuming particles follow the Reynolds-averaged flow, although some other simple passive and active particle behaviors are also treated. Turbulence effects are treated using a random walk algorithm with spatial step lengths randomly chosen from Gaussian distributions characterized by the diffusivity from the flow solver. Our work extends this concept to a general framework that is solver and coordinate system independent to allow easy comparisons between differing flow treatments. To better treat problems where detailed information is required in specific regions, the approach includes novel cloning and colligation algorithms which enhance local resolution at modest computational expense. We also provide tools for computing local concentrations and total exposure over a user-specified time interval. Several examples of predictions are provided to illustrate applications of the technique, including examination of the role of curvature-driven secondary flows, storage in lateral separation eddies, treatment of larval drift, treatment of fuel spill dispersion, river-floodplain connections, and sedimentation in floodplain ponds by tie channel connections. We also demonstrate that the model can reproduce analytically derived concentration profiles for simple diffusivities. These examples show that the Lagrangian particle tracking approach and the extensions proposed here are broadly applicable and viable for treating difficult river problems with multiple temporal and spatial scales. The examples also illustrate the utility of the cloning/colligation extensions and show how these can decrease the computational effort required on problems where high local resolution is required. Enhancement of the tools and even broader applicability can be achieved through the inclusion of multiple particle populations and particle–particle interactions.     

Seasonal variation and flux of dissolved nutrients in the Danshuei Estuary, Taiwan: A hypoxic subtropical mountain river

Comprehensive bimonthly field surveys were carried out from September 2000 to June 2002 to study the seasonal dynamics and the inter-annual variability of dissolved inorganic nitrogen (DIN; nitrate, nitrite and ammonium) and dissolved inorganic phosphorus (DIP) in a subtropical mountain river system, the Danshuei tributary, the largest urbanized estuarine system in Taiwan. The headwaters were found to be well aerated, saturated with oxygen, with low ambient DIN (<9 μM) and DIP (<0.2 μM) concentration. As the river flows through the city of Taipei, the river becomes hypoxic because re-aeration rates cannot keep up with elevated oxygen consumption, and the concentrations of DIP (7.53 μM) and DIN (390 μM) increase drastically. Conservative mixing was mostly observed for silicate while DIP and DIN mostly showed non-conservative removal characteristics. Silicate originates from weathering and erosion of bedrocks in the watershed, whereas nitrogen- and phosphorus-bearing nutrients come mainly from urban discharges. Ammonium is the predominant dissolved nitrogenous species, ranging from 10 to 1000 μM. The nutrient chemistry is complex and dynamic due to anthropogenic perturbations and reactions in the tidally mixed zone of strong redox gradients. On average, the annual loading rates of dissolved phosphate and dissolved inorganic nitrogen from the Danshuei River to the ocean are 0.1 and 3.2 Gmol/year, respectively, which represent 0.1% and 0.2% of the world's total river discharge of dissolved inorganic nitrogen and phosphate.