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991.
大港油田官80断块辫状河储层构型表征 总被引：1，自引：1，他引：0
为研究辫状河复合河道砂体心滩坝(对应Miall的四级界面,相当于单一沉积微相级别),以大港油田官80断块为研究区,以枣Ⅲ油组的单层为研究层位,应用密井网信息(岩心、测井、动态资料)、现代沉积和露头测量资料,采用分级描述、模型构建、交叉验证方法,分析河道砂体多级次界面及构成单元的定量几何特征,建立河道砂体构型定量模式,进行砂体构型分析及三维建模,以及研究区储层构型表征与建模,分析深化辫状河储层内部非均质性和剩余油分布,为油田开发动态分析、剩余油挖潜提供更准确的地质依据. 相似文献
992.
The statistical properties of annual runoff in major rivers of China are studied based on the theory of stochastic process and technology of time series analysis. These properties include the characteristics of intra‐annual and inter‐annual variations of runoff, trends, abrupt changes and periodicities. The new findings from the intensive calculations and appropriate analysis of data in longer period are as follows: (i) compared with the nonuniformity of intra‐annual runoff before 1980, the nonuniformity of intra‐annual runoff in China generally decreased after 1980, except for Huaihe River and Songhua River; (ii) compared with the annual runoff before 1980, the annual runoff in China generally decreased after 1980 except for WangJiaba station in Huaihe River and Ha‐Erbin station in Songhua River; the frequency of continuous low flow and continuous high flow in Haihe River and the downstream of Yellow River is higher than those in other rivers in China; (iii) annual runoff shows a downward trend in major rivers of China especially in Haihe River, Liao River and the midstream and downstream of Yellow River; (iv) there exist certain abrupt changes of annual runoff in major rivers of China; the abrupt change‐points are different among different river basins; and (v) almost periodicities of annual runoff sequences in major rivers of China are generally 20 years below, that is, 3~7 and 12~20 years. The reasons for these changes are mainly caused by climate change and human activities. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
993.
Inner gorges often result from the propagation of erosional waves related to glacial/interglacial climate shifts. However, only few studies have quantified the modern erosional response to this glacial conditioning. Here, we report in situ 10Be data from the 64 km2 Entlen catchment (Swiss Alps). This basin hosts a 7 km long central inner gorge with two tributaries that are >100 m‐deeply incised into thick glacial till and bedrock. The 10Be concentrations measured at the downstream end of the gorge yield a catchment‐wide erosion rate of 0.42 ± 0.04 mm yr‐1, while erosion rates are consistently lower upstream of the inner gorge, ranging from 0.14 ± 0.01 mm yr‐1 to 0.23 ± 0.02 mm yr‐1. However, 10Be‐based sediment budget calculations yield rates of ~1.3 mm yr‐1 for the inner gorge of the trunk stream. Likewise, in the two incised tributary reaches, erosion rates are ~2.0 mm yr‐1 and ~1.9 mm yr‐1. Moreover, at the erosional front of the gorge, we measured bedrock incision rates ranging from ~2.5 mm yr‐1 to ~3.8 mm yr‐1. These rates, however, are too low to infer a post‐glacial age (15–20 ka) for the gorge initiation. This would require erosion rates that are between 2 and 6 times higher than present‐day estimates. However, the downcutting into unconsolidated glacial till favored high erosion rates through knickzone propagation immediately after the retreat of the LGM glaciers, and subsequent hillslope relaxation led to a progressive decrease in erosion rates. This hypothesis of a two‐ to sixfold decrease in erosion rates does not conflict with the 10Be‐based erosion rate budgets, because the modern erosional time scale recorded by 10Be cover the past 2–3 ka only. These results point to the acceleration of Holocene erosion in response to the glacial overprint of the landscape. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
994.
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996.
Hyperscale terrain modelling of braided rivers: fusing mobile terrestrial laser scanning and optical bathymetric mapping 
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下载免费PDF全文 Quantifying the morphology of braided rivers is a key task for understanding braided river behaviour. In the last decade, developments in geomatics technologies and associated data processing methods have transformed the production of precise, reach‐scale topographic datasets. Nevertheless, generating accurate Digital Elevation Models (DEMs) remains a demanding task, particularly in fluvial systems. This paper identifies a threefold set of challenges associated with surveying these dynamic landforms: complex relief, inundated shallow channels and high rates of sediment transport, and terms these challenges the ‘morphological’, ‘wetted channel’ and ‘mobility’ problems, respectively. In an attempt to confront these issues directly, this paper presents a novel survey methodology that combines mobile terrestrial laser scanning and non‐metric aerial photography with data reduction and surface modelling techniques to render DEMs from the resulting very high resolution datasets. The approach is used to generate and model a precise, dense topographic dataset for a 2.5 km reach of the braided Rees River, New Zealand. Data were acquired rapidly between high flow events and incorporate over 5 x 109 raw survey observations with point densities of 1600 pts m‐2 on exposed bar and channel surfaces. A detailed error analysis of the resulting sub‐metre resolution is described to quantify DEM quality across the entire surface model. This reveals unparalleled low vertical errors for such a large and complex surface model; between 0.03 and 0.12 m in exposed and inundated areas of the model, respectively. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
997.
Estimating fluvial wood discharge using time‐lapse photography with varying sampling intervals 下载免费PDF全文
下载免费PDF全文 Monitoring large wood (LW: width > 10 cm, length > 1 m) in transport within rivers is a necessary next step in the development and refinement of wood budgets and is essential to a better understanding of basin‐wide controls and patterns of LW flux and loads. Monitoring LW transport with coarse interval (≥ 1 min) time‐lapse photography enables the deployment of monitoring cameras at large spatial and long temporal scales. Although less precise than continuous sampling with video, it allows investigators to answer broad questions about basin connectivity, compare drainages and years,and identify transport relationships and thresholds. This paper describes methods to: (i) construct fluvial wood flux curves; (ii) analyze the effects of sample interval lengths on transport estimates; and (iii) estimate total wood loads within a specified time period using coarse‐interval time‐lapse photography. Applying these methods to the Slave River, a large‐volume (103 m3 s‐1), low‐gradient (10? 2 m km? 1) river in the subarctic (60° N), yielded the following results. A threshold relationship for wood mobility was located around 4500 m3 s‐1. More wood is transported on the rising limb of the hydrograph because wood flux declines rapidly on the falling limb. Five‐ and ten‐minute sampling intervals provided unbiased equal variance estimates of 1 min sampling, whereas 15 min intervals were biased towards underestimation by 5–6%, possibly due to periodicity in wood flux. Total LW loads estimated from the 1 min dataset and adjusted for a 15% misdetection rate from 13 July to 13 August are: 1600 ± 200 # pieces, 600 ± 200 m3 and of the order of 1.3 × 105 kg carbon. The total wood load for the entire summer season is probably at least double this estimate because only the second half of the summer was monitored and a large early summer peak freshet was missed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
998.
AbstractIn 2007, the Texas legislature created a program to identify environmental flow standards statewide through the coordinated efforts of scientific and stakeholder groups and rulemaking by the Texas Commission on Environmental Quality. To aid in this task, a Hydrology-based Environmental Flow Regime (HEFR) method was developed that combines a suite of user-customizable hydrologic statistics with an implementation framework. Following the concepts of the Natural Flow Paradigm, the methodology includes the separation of a long-term hydrograph into key flow components (e.g. subsistence, base, high-flow pulse and overbank) defined by the Texas Instream Flow Program. Seasonal, annual and inter-annual flow component statistics were then coupled with biology, water quality and geomorphology overlays, where available, and with implementation rules applied to example large-scale water supply projects to support development of environmental flow standards for use in water rights permit conditions. The HEFR methodology and resulting flow recommendations are compared to two contemporary in-stream flow studies and adopted environmental flow standards. Subsistence flows were fairly similar. Baseflows were in a similar range, but fewer than three seasonal levels have sometimes been specified in in-stream flow studies. Episodic events are quite different in terms of magnitude, frequency, duration and applicable number.
Editor D. Koutsoyiannis; Guest editor M. AcremanCitation Opdyke, D.R., Oborny, E.L., Vaugh, S.K., and Mayes, K.B., 2014. Texas environmental flow standards and the hydrology-based environmental flow regime methodology. Hydrological Sciences Journal, 59 (3–4), 820–830. 相似文献
999.
The Alpine Orogen in the Mediterranean region exhibits a series of orogenic curvatures (oroclines). The evolution of these oroclines is relatively well constrained by a plethora of geophysical and geological data, and therefore, their origin can inform us on the fundamental processes controlling oroclinal bending. Here, a synthesis of the geometry of Mediterranean oroclines, followed by a discussion on their geodynamic origin is presented. The geometrical synthesis is based on a new classification of Mediterranean oroclines, which defines a first-order orocline (Adriatic Orocline) by the general northward-convex shape of the Alpine Orogen from Cyprus to Gibraltar. Superimposed on the limbs of this orocline, are second-, third- and fourth-order oroclines. The major process that led to the formation of the Adriatic Orocline is the indentation of Adria into Europe, whereas second- and third-order oroclines (e.g., Western Mediterranean and Gibraltar oroclines, respectively) were primarily controlled by a combination of trench retreat and slab tearing. It appears, therefore, that the geodynamics of Mediterranean oroclines has been entirely dependent on plate boundary migration and segmentation, as expressed in the interlinked processes of indentation, trench retreat and slab tearing. The relative contribution of specific geodynamic processes, and their maturity, could be inferred from geometrical characteristics, such as the amplitude-to-width ratio, the orientation of the curvature (convex or concave) relative to the convergence vector, and their geometrical relationship with backarc extensional basins (e.g., in the concave side of the orocline). Based on the information from the Mediterranean oroclines, it is concluded that oroclinal bending commonly involves lithospheric-scale processes, and is not restricted to thin-skinned deformation. However, contrary to previous suggestions that assume that the whole lithosphere can buckle, there is no clear evidence that such processes occur in modern tectonic environments. 相似文献
1000.
象山港流域河流形态特征定量分析 总被引：2，自引：0，他引：2
象山港流域发育有自低山流向海洋的众多山溪型河流,形成相对独立的小流域。本文采用流域地貌数学模型与地理信息系统技术相结合的方法,对港湾内小尺度河流特征进行了定量分析。结果表明:(1)象山港流域河流的河长分维值普遍较小,大嵩江的河长最长且主河道最为蜿蜒曲折;(2)凫溪和大嵩江的水系结构较象山港流域其它河流的结构更为复杂且发育更加充分;(3)除了颜公河和钱仓河外,流域内大部分河流纵剖面线呈现下凹型且主河道有多次阶梯状起伏;(4) 基岩性S-A模型的应用具有一定的局限性,凫溪和大嵩江的基岩河床处于均衡状态。 相似文献