汊口滩沉积特征及沉积模式——以鄱阳湖赣江三角洲汊口滩为例     

李燕  金振奎  高白水  石良  李桂仔 《吉林大学学报(地球科学版)》2021,51(6):1678-1688

随着我国许多油田进入高含水开发阶段,剩余油挖潜难度增大,复合分流河道带和单河道的划分已不能满足生产要求,迫切需要进行分流河道内部有利砂体的识别。现代沉积研究是认识分流河道内砂体发育特征的有效手段。通过对鄱阳湖赣江三角洲的现场考察,发现汊口滩是三角洲分流河道中发育的重要砂体类型,以发育在分流河道的分汊口处为典型特征。根据水动力条件、沉积物组合、沉积构造等特征,将汊口滩划分为滩头、滩中、滩尾3个沉积单元。从滩头到滩尾具有水动力条件减弱、沉积物层理规模减小、单砂层厚度减小、粒度变细、泥质夹层增多的特点。汊口滩主要是由于在分汊口处,水流受到汊口的顶托作用流速降低,沉积物按粒度分异堆积形成;堆积方式主要以向上游方向的逆流加积为主。与水道砂体相比,汊口滩发育的层理类型多,而且内部夹层发育,非均质性更强;由于夹层的遮挡作用,砂体不易发生水淹,有利于形成剩余油的富集区。  相似文献   

白天和夜间通用的卫星遥感沙尘判识算法构建与验证分析     

王威  胡秀清  张鹏  闵敏 《气象》2019,45(12):1666-1679

Himawari-8是日本发射的新一代静止气象卫星,与前一代的MTSAT-2相比,在时间、空间分辨率上都有了很大提升,特别是红外通道数量从4个增至10个,为红外遥感沙尘提供了新的观测数据。本研究利用Himawari-8的红外观测数据,发展了仅用红外通道的沙尘全天候判识算法,可以实现对白天和夜间的连续监测。算法在前人基础上去除了可见光通道,同时引入更多红外通道来进行云检测和沙尘判识。由于一日之中,地表温度发生变化,因此针对白天和夜间设置了两套不同的判别阈值,来保证算法的全天适用性。最后通过两次沙尘事件对沙尘判别结果的分析和检验表明,遥感判识结果与地面气象站和PM_(10)观测较为一致,说明了只用红外通道全天候判识沙尘的可行性。  相似文献   

Enhancement of the channel routing module in SWAT     

Nam Won Kim  Jeongwoo Lee 《水文研究》2010,24(1):96-107

The objective of this study is to demonstrate that the channel flow routing techniques used in the Soil and Water Assessment Tool (SWAT) can be sometimes inappropriate for runoff simulation in small basins. Simulated hydrographs have a tendency to underestimate peak flows or may send a false signal during the recession periods when SWAT is applied to the Mihocheon Basin in South Korea. This was particularly evident for sub‐basins that had a short travel time of much less than a day. In order to enhance the channel routing module in SWAT, an alternative routing technique in which Manning relationship is combined with a simple channel reach continuity equation is proposed in the present study. The advantage of the proposed routing technique is that parameters are readily available from channel morphological data and that it is applicable to small basins. Through simulations of specific events, this routing module that is incorporated into SWAT is almost free from instability errors and produces realistic flow depths and velocities unlike the original version of SWAT with Muskingum method. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Asymptotic Rayleigh instantaneous unit hydrograph     

B. M. Troutman  M. R. Karlinger 《Stochastic Environmental Research and Risk Assessment (SERRA)》1988,2(1):73-78

The instantaneous unit hydrograph for a channel network under general linear routing and conditioned on the network magnitude,N, tends asymptotically, asN grows large, to a Rayleigh probability density function. This behavior is identical to that of the width function of the network, and is proven under the assumption that the network link configuration is topologically random and the link hydraulic and geometric properties are independent and identically distributed random variables. The asymptotic distribution depends only on a scale factor, , where is a mean link wave travel time.  相似文献   

Channel and floodplain response to recent abrupt climate change: The tyne basin,Northern England     

Barbara T. Rumsby  Mark G. Macklin 《地球表面变化过程与地形》1994,19(6):499-515

This paper examines the timing, nature and magnitude of river response in upland, piedmont and lowland reaches of the Tyne basin, northern England, to high-frequency (20–30 year) changes in climate and flood regime since 1700 AD. Over this period fluvial activity has been characterized by alternating phases of river-bed incision and stability coinciding with non-random, decadal-scale fluctuations in flood frequency and hydroclimate that appear to be linked to changes in large-scale upper atmospheric circulation patterns. Episodes of widespread channel bed incision (1760–1799, 1875–1894, 1955–1969) result from a higher frequency of large floods (> 20 year return period) and cool, wet climate under meridional circulation regimes. Phases of more moderate floods (5–20 year return period), corresponding to zonal circulation types (1820–1874, 1920–1954), are characterized by enhanced lateral reworking and sediment transfer in upper reaches of the catchment, and channel narrowing and infilling downstream. Rates of fluvial activity are reduced in intermediate periods (1800–1819, 1895–1919) with no dominant circulation regime associated with lower flood frequency and magnitude. The results of this study provide a valuable guide for forecasting probable drainage basin and channel response to future climate change.  相似文献   

Explorations into the formal structure of drainage basins     

Christian Werner 《地球表面变化过程与地形》1994,19(8):747-762

Every basin of higher than first order is drained by a channel network composed of two subnetworks. Their basins are separated by a drainage divide line, called the basin divider, which is the primary organizing feature of the main basin. Each basin of magnitude n contains n – 1 subnetworks of higher order, and is therefore organized by a set of n – 1 dividers. The dividers and the basin boundary are interconnected in a graph called the divider network of the basin; in graph-theoretic terms this network forms a tree and has the same magnitude and link numbers as the channel network draining the basin. While the subbasins and subnetworks of a drainage basin form a nesting hierarchy, the corresponding dividers do not; indeed, any two dividers share at most one node in common, and whether they do so is independent of whether the corresponding subbasins are nesting or disjoint. However, the dividers of nesting basins are linked by recursive relationships which permit the derivation of a set of algebraic equations; these equations relate the dividers of a basin to other basin components; for example, their combined length is equal to half the length of all first-order basin boundaries minus the length of the main basin boundary. The second part of the paper explores the dependence of the divider length on other basin parameters. The expected length, as predicted by the assumption of topological randomness, is clearly rejected by the data. An alternative approach (regression) is based on the observed magnitudes of the subbasins separated by each divider, and is reasonably successful in estimating divider length. The last section introduces the concept of the standardized basin defined by a boundary length of unity; the estimated lengths of the basin divider and the basin boundary permit an approximate reconstruction of the idealized basin shape and the location of the divider in it.  相似文献   

开敞水域中航槽流场的数值模拟   总被引：2，自引：0，他引：2       下载免费PDF全文

陆永军  赵连白 《水科学进展》1994,5(3):208-213

建立了一个模拟开敞水域中航槽流场的平面二维数学模型.利用该模型计算得到的流速分布与袁美琦、李安中等人试验值相吻合,并计算了相当于天然情况下(各种水深、挖深比及航槽与水流的不同交角)的流场,得到了各种航槽与水流交角、不同挖深比的航槽流速折减系数变化规律图,及各种航槽与水流交角、不同挖深比的航槽中流向与航槽轴线交角的变化规律图,为开敞水域中航槽选线设计提供了依据.  相似文献   

THE　RIVER　CHANNEL　ADJUSTMENT　AS　INFLUENCED　BY　THE　FLOODPLAIN　GEOECOSYSTEM：　AN　EXAMPLE　FROM　THE　HONGSHAN　RESERVOIR     

XU Jiongxin  SHI Changxing 《国际泥沙研究》1994,(3)

ＴＨＥＲＩＶＥＲＣＨＡＮＮＥＬＡＤＪＵＳＴＭＥＮＴＡＳＩＮＦＬＵＥＮＣＥＤＢＹＴＨＥＦＬＯＯＤＰＬＡＩＮＧＥＯＥＣＯＳＹＳＴＥＭ：ＡＮＥＸＡＭＰＬＥＦＲＯＭＴＨＥＨＯＮＧＳＨＡＮＲＥＳＥＲＶＯＩＲ￥ＸＵＪｉｏｎｇｘｉｎ；ＳＨＩＣｈａｎｇｘｉｎｇ（Ｐｒ...  相似文献   

长江中下游近期河道演变及其主要影响因素   总被引：5，自引：0，他引：5       下载免费PDF全文

朱立  蔡鹤生 《地球科学》1995,20(4):427-432

长江河道变迁直接影响其两岩的经济开发和人民生活。本文较详细地阐述了长江中下游近期江岸的冲淤变化、江心洲的演变及岸崩塌变形的特征及规律，分析了影响其演变的主要因素，进而预测了江岸的冲淤趋势。  相似文献   

从水流挟沙力和河槽形态规律分析黄河调水调沙   总被引：3，自引：0，他引：3  

张遂业  涂启华 《水文》2005,25(6):33-36

在分析水流挟沙力和河槽水力形态规律的基础上，研究调节流量、含沙量和泥沙组成的优化组合，解决河道输沙减淤和河槽相对稳定问题，提出调水调沙方向。达到合理利用水资源和河道减淤与治理相结合的目的．  相似文献