悬移质挟沙能力水槽试验研究

利用0.03 mm黄土和卵石碾成粉末制成的0.03 mm人工沙,0.06 mm黄土,0.13 mm黄沙,共计4种沙样,在槽长33 m,宽1.25 m,深0.5 m,可以调节坡度的钢板水槽内按系统试验方法进行饱和含沙量试验.进槽含沙量较高,含沙量沿程降低,底部泥沙淤积,形成沙波,待水流中含沙量在1～2 h内保持不变时,定义为极限或饱和含沙量.每次试验测定含沙量、流速、水深、水面比降、悬沙颗粒级配、槽底泥沙淤积比降、槽底泥沙颗粒级配等数据,探求细粒泥沙在一定条件下的饱和悬沙含量,即悬移质挟沙能力.试验观测及理论分析表明,在恒定均匀水流条件下,浑水悬沙饱和含沙量取决于悬浮泥沙的沉速、水流流速、水深、水力半径、水面比降、底部淤沙粒径各水沙因子.在寻求挟沙能力经验公式中,除水流本身紊动挟沙外,还应考虑底部含沙量,淤沙粒径,包括糙率(沙波高度)和底沙运动,对输沙的影响,所求得的经验公式包括Velikanov公式诸因子以及底沙受水流剪力流速和底沙粒径的比值的因子.天然渠道资料检验说明了公式的适用性.

悬移质模型沙级配的模拟计算方法探讨

对于研究泥沙问题的动床模型试验 ,模型沙的选择是模型设计的关键。模型沙的选择是指综合考虑所研究问题的性质、已知条件、模型几何比尺 ,以满足模型与原型的水沙运动相似为目的 ,选定、设计模型沙的材料、比重和粒径级配。作者主要阐述悬移质模型沙级配的模拟方法 ,并提出利用沙玉清公式计算、设计模型沙级配的另一种方法 ,以尽可能严格满足模型相似条件、克服老方法的不足和缺陷。

计算分析法确定悬移质单沙取样垂线位置

对于悬移质单沙取样垂线位置的确定,通常是选取几次能代表各级水位、各级含沙量的输沙率资料,绘制垂线平均含沙量与断面平均含沙量比值的横向分布图,在图上选择其值最为集中,且等于1处,作为悬移质单沙取样垂线位置。有的站断面含沙量分布较均匀,或在某个区域分布较均匀,其集中的垂线在所设垂线中会有多条出现,仅凭肉眼在图上难以准确找出比值最集中而且在1附近的垂线。文中对这个问题加以探讨,并推荐一种分析的方法。

海岸河口泥沙数学模型研究进展

对海岸河口泥沙运动的基本方程、数值方法、边界条件、参数选取等进行了归纳总结和评述,以期对本学科的发展起到一定的引导和促进作用。

庙宫水库减缓淤积调度方式初探

庙宫水库位于滦河最大的支流——伊逊河上，水库兴建于1959年，1960年开始蓄水，总库容1．83亿m^3，控制流域面积2370km^2，占伊逊河流域总面积的35％。伊逊河为多沙性河流，水库多年平均入库悬移质沙量0．05亿t，平均含沙量40kgm^3(与黄河陕县站相当)，因此。

Characteristics of Suspended Particulate Matter and the Coastal Turbidity Maximum Areas of the Mekong River

This paper presents the results of application of a 3D （three-dimensional） numerical model to study on MTZ （maximum turbidity zone） in the coastal zone of Mekong River Delta. In this study, a 3D system model with combination of hydrodynamics--wave and suspended sediment transport was set up and validated with measured data in the study area. Based on calculated scenarios for the flood and the dry season, the results have shown appearance of MTZs in the coastal zone of Mekong River with suspended sediment concentration prevalent of 0.04-0.07 kg·m^3 （the dry season） and 0.05-0.1kg·m^3 （the flood season）. The position and MTZs scale change with the interaction between fresh water and tidal oscillations. The MTZ occur more in the dry seasons compared to the wet season. The MTZs are prevalent located far away from estuaries about in 12-22 km （in the dry season）, and 5-15 km in the flood season.

Sediment Load of Asian Rivers flowing into the Oceans and their Regional Variation

Study of the major Asian rivers discharge to the ocean reveals variations of their water discharges and sediment loads, and local characteristics of river sediment concentrations. On the basis of this, the Asian rivers fall into three regions, including Eurasia Arctic, East Asia, Southeast and South Asia Regions. The Eurasia Arctic Region is characterized by the lowest sediment concentration and load, while the East Asia Region is of the highest sediment concentration and higher sediment load, and the South-East and South Asia Region yields higher sediment concentration and highest sediment load.The sediment loads of these regions are mainly controlled by climate, geomorphology and tectonic activity. The Eurasia Arctic rivers with large basin areas and water discharge, drain low relief which consists of tundra sediment, thus causing the lowest sediment load. The East Asia rivers with small basin areas and lowest water discharges, drain extensive loess plateau, and transport most erodible loess material, which results in highest sediment concentration. The SE and South Asia rivers originating from the Tibet Plateau have large basin areas and the largest water discharges because of the Summer Monsoon and high rainfall influence, causing the highest sediment load.In Asia, tectonic motion of the Tibet Plateau plays an important role. Those large rivers originating from the Tibet Plateau transport about 50% of the world river sediment load to ocean annually, forming large estuaries and deltas, and consequently exerting a great influence on sedimentation in the coastal zone and shelves.

Numerical Analysis of Adaptation-to-capacity Length for Fluvial Sediment Transport

Over the last several decades,various sediment transport capacity formulations have been used by geomorphologists and engineers to calculate fluvial morphological changes.However,it remains poorly understood if the adaptation to capacity could be fulfilled instantly in response to differing inflow discharges and sediment supplies,and thus if the calculation of morphological changes in rivers based on the assumed capacity status is fully justified.Here we present a numerical investigation on this issue.The distance required for sediment transport to adapt to capacity(i.e.,adaptation-to-capacity length) of both bed load and suspended sediment transport is computationally studied using a coupled shallow water hydrodynamic model,in line with varied inlet sediment concentrations.It is found that the adaptation-to-capacity length generally decreases as the Rouse number increases,irrespective of whether the inlet sediment concentration increases or reduces.For cases with vanishing inlet sediment concentration a unified relationship is found between the adaptation-to-capacity length and the Rouse number.Quantitatively,the adaptation-to-capacity length of bed load sediment is limited to tens of times of the flow depth,whilst that of suspended sediment increases substantially with decreasing Rouse number and can be up to hundreds of times of the flow depth.The present finding concurs that bed load sediment transport can adapt to capacity much more rapidly than suspended sediment transport,and it facilitates a quantitative criterion on which the applicability of bed load or suspended sediment transport capacity for natural rivers can be readily assessed.

Eco-drainage Pond in Non Irrigated Land for the Conservation of Land and Water Based on Community Participation

There are some bad impacts from a critical land such as flood in rainy season and dryness in dry season. Long dryness could cause shortage of water for human consumption, industry and agriculture. Prevention has been made to avoid the both bad impacts by building hydraulic structures like reservoirs and ponds in order to reduce the peak flow during the rainy season and to store the water for use during the dry season. However, they gradually become full of sediment. This will make them work insufficiently and will cause high maintenance cost. Moreover, wells in agriculture field used as retention also suffer dryness to make crop failure. This study aims to develop a model of pond for conservation of land and water in non irrigated land. Community participation is crucial in order to solve the flood and dryness problems. The community, especially the farmers will participate actively in the implementation and maintenance of the model. There are benefits in using the pond model such as： （1） to control sediment transport to the rivers, reservoir or other hydraulic structures; （2） to reduce flood rate; （3） to increase ground water recharge; （4） to contain water for agriculture and （5） to control the fertility of land. The cost of making a unit of model （sedrainpond） of 1.5 m diameter and 1.5 meter depth is relatively cheap between $10 to $20 （US）, and the maintenance is done by the farmers. When the pond model becomes functional, besides containing water in the rainy season, the water can be used to sustain water for agriculture in the dry season to avoid any crop failure. When the pond becomes dry, the farmers can harvest the suspended load sediment such as clay or silt to spread onto their land to keep its fertility.