Flow and sedimentary processes in the meandering river South Esk,Glen Clova,Scotland   总被引：1，自引：0，他引：1  

John S. Bridge  Jack Jarvis 《地球表面变化过程与地形》1976,1(4):303-336

Channel geometry, flow and sedimentation in a meander bend of the River South Esk were studied from bankfull stages (January–February) to low water stages (May) in 1974. Bed topography varied little over the study period, showing a typical pool and ripple geometry. Variation of mean depth and velocity with discharge differed from section to section around the bend, due primarily to locally varying flow resistance with stage. The flow pattern for all stages was dominated by a single spiral over the point bar, with a development zone at the bend entrance. Deviation of bed shear stress from the mean flow direction was in general accord with theory, especially for high stages. The use of a uniform longitudinal water surface slope in the calculation of bed shear stress is not justified because of a complicated water surface topography, also such calculated shear may not represent effective bed shear on grains, as it accounts also for energy losses associated with secondary flows. Dunes covered much of the bar at high stages, with increasing proportions of ripples, sand ribbons and lower phase plane beds at low stages. Local flow resistance generally decreases from dunes, diminished and ripple-backed dunes, ripples, sand ribbons to plane beds, and bed forms are predicted quite well by the stream power-grain size scheme. Mean size, sorting and skewness of sediment over the bed changes little with stage. In general, size decreases, sorting improves and skewness changes from positive to negative from the talweg to the inner bank, and in the downstream direction. Allen's (1970a, b) force balance equation for moving bed load particles is supported for bankfull stage, with some reservations, and textural characteristics are explained by progressive sorting in the direction of sediment transport. Large-scale trough cross stratification (with some flat bedding) formed at high stage by dunes (and lower phase plane beds) dominates the point bar sediments. Alternations of fine-medium sand (often cross-laminated) and vegetation-rich layers result from periodic deposition on the grassed upper bar surface. Fining upwards sequences produced by lateral channel migration are modified by a coarsening upward subsequence in the upstream bar region where spiral flow is developing from the bend upstream.  相似文献   

Stable channel analysis with sediment transport for rivers in Malaysia: A case study of the Muda,Kurau, and Langat rivers     

《国际泥沙研究》2020,35(5):455-466

Assessments of a stable channel were done to evaluate the conditions of three rivers in Malaysia, using an analytical method that modifies the stable channel flowchart developed by Chang (1988) and Ariffin (2004). The analytical approach was selected to calculate the suitable dimensions for a stable channel, using equations that describe the physical relation of sediment transport, flow resistance, and dynamic equilibrium. Measured field data were used as the input data for the stable channel program, which then processed the data until the input discharge was equal to the output discharge. However, this method depends on the accuracy of the sediment transport equation that is used in the stable channel design. Existing equations recommended by the Department of Irrigation and Drainage (DID), Malaysia, were found to be unsuitable because of their low discrepancy ratio (DR) values, which were below 42%. These are the equations of Engelund and Hansen (1967) and Yang (1979), as well as existing local equations from Ariffin (2004) and Sinnakaudan et al. (2006). Therefore, revised equations were developed in the current study to increase the accuracy of the total bed material load equations for use in Malaysian rivers. The newly revised Ariffin (2004) and Sinnakaudan et al. (2006) equations yielded better DRs of 66.34 and 64.49%, respectively. River assessments done on the Kurau River (a small river), the Muda River (a medium-size river), and the Langat River (a large river) show that these rivers have experienced different levels of erosion. Only the Kurau River was found to have minimal erosion and sedimentation levels. Conversely, stable channel assessments for the Muda River and the Langat River revealed that both rivers had experienced severe erosion, due to excessive sand mining. Almost all the cross section sampling points on the Muda River and Langat River were deeper than the suggested stable channel heights.  相似文献   

城市江堤外移工程对防洪影响研究   总被引：7，自引：0，他引：7       下载免费PDF全文

陆永军  郝嘉凌  李浩麟 《水科学进展》2003,14(2):197-202

以浙江省温州市瓯江江堤外移工程为例,应用二维潮流数学模型研究了堤线外移的不同工程方案对城市防洪的影响。该模型能够模拟瓯江与楠溪江交汇引起的复杂水流运动,以及多岛屿对水流流场的影响。验证计算表明,计算的潮位及18条垂线流速及断面流量过程与实测值吻合较好,误差均小于10%。因堤线外移的部分大多位于河道岸线的凹囊,适当外移可使河道岸线更趋平顺。100年一遇洪水时,瓯江大桥至鱼旗山堤线外移曲线方案1与直线方案2分别使屿头山-梅岙河段最高潮位壅高0.03～0.04m及0.04～0.08m。多年平均流量450m3/s时,方案2使塔山至鱼旗山断面垂线平均流速增加6%～22%,工程段以外河段流速变化较小;方案1缩窄的河宽和拦截过水面积明显小于方案2,相应引起流速变化也较小。  相似文献   

入海水系整治水情数值模拟方法   总被引：1，自引：0，他引：1  

陆建华  韩龙喜  王训明  吴宏峰 《水文》2003,23(4):13-16

入海水系河道纵横交错，其水流同时受上游河道来水、下游出口潮汐顶托、水工建筑物调控等的综合影响，水文情势十分复杂。采用水文预报与数值模拟结合的方法，对上游各边界河道采用由瞬时单位线法推得的设计洪水过程作为入流条件，对入海边界根据潮位过程及水工建筑物调节规程确定出流边界条件，进行了来水与潮位不同遭遇多种工况下的水文水流预测模拟，为水系整治提供水情依据。  相似文献   

二维明渠非恒定流的格子Boltzmann模拟   总被引：5，自引：0，他引：5       下载免费PDF全文

程永光  索丽生 《水科学进展》2003,14(1):9-14

根据二维浅水波方程的特点,应用由格子Boltzmann方程展开的多尺度方程,建立了一个能模拟二维明渠非恒定流的格子Boltzmann模型。通过对一维溃坝波和二维圆形溃坝波的模拟分析,验证了该模型的有效性。以某水电站尾水渠为例,模拟分析了由机组甩负荷和增负荷引起的水位波动规律,为尾水渠的设计提供了依据。  相似文献   

辽河盆地曙一区馆陶组湿地冲积扇沉积   总被引：20，自引：0，他引：20  

郭建华  朱美衡  杨申谷  刘辰生 《沉积学报》2003,21(3):367-372

在岩芯观察的基础上,结合地震资料和测井资料对该区馆陶组粗碎屑岩进行了详细的研究,认为该套粗碎屑岩属湿地冲积扇沉积。进而分析了馆陶组湿地冲积扇的岩性特征、古气候特征、微相类型,并总结出了这种冲积扇的沉积模式。在此基础上,进一步阐明了基准面旋回对沉积相纵横向展布的影响.  相似文献   

PCVSAT单收站数据收集实时监视系统   总被引：2，自引：0，他引：2       下载免费PDF全文

姚燕  李湘  周勇 《气象》2003,29(5):30-33

主要介绍了PCVSAT单收站数据收集实时监视系统的主要功能和技术特点。该系统直观、灵活地实现了对所有卫星信道发送、接收和缺收文件实时信息的详细查询、打印和保存等功能，同时具备了监视主要通道的状态和数据收集情况及实时报警的功能，满足了实时监视业务的需求。  相似文献   

2001年夏季安徽、江西、福建对流云分布特征     

胡雯　黄勇谢重阳  蒋年冲管金胜　申宜运 《应用气象学报》2003,14(Z1):135-142

利用2001年夏季(7、8、9月)GMS-5卫星云图资料,统计分析了中国南方安徽、江西、福建三省夏季对流云的分布特征.结果表明,中国南方夏季对流云时空分布很不均匀,不同地区、不同时段均表现出较大的差异;无论是从对流云出现频数还是云区面积来看,混合云在南方对流云中占绝对优势,是南方降水的主要降水云,但暖云仍然是不可忽视的云水资源.  相似文献   

煤层中的河道泥石流相沉积及相关采煤生产措施   总被引：1，自引：0，他引：1  

王宇林  李永化  张学义 《中国地质灾害与防治学报》2003,14(1):68-71

在陆相含煤断陷盆地，煤层中的河道泥石流相沉积通常比较发育，并成为影响采煤生产的重要地质因素。以铁法盆地大兴井田为例，文章论述了煤层中的河道泥石流相沉积发育的地质背景，指出冲积扇前泥炭沼泽是这类河道泥石流的多发地段，冲积扇源洪水是形成煤层中河道泥石流相沉积的主要因素；从岩石学、几何形体等方面阐述了煤层中河道泥石流相沉积特征；并根据煤层中河道泥石流的平面分布规律，提出相关采煤生产方案以减小或避免这类泥石流相沉积对采煤生产的负面影响。  相似文献   

在煤田地震勘探中与速度无关的DMO技术探讨     

刘志臣 《中国煤田地质》2003,15(5):57-58

由于煤田地质条件的局限性,与速度无关DMO的技术,在实际应用中只能用均方根速度来近似地震反射波的速度,而在速度分析中,较好的办法是在DMO后得的道集上作DMO速度分析,同时注意数据处理参数的合理选择,与速度无关的技术才能在煤田地震勘探中取得很好的应用效果。  相似文献