Progradational sand-mud deltas in lakes and reservoirs. Part 2. Experiment and numerical simulation
Progradational sand-mud deltas in lakes and reservoirs. Part 2. Experiment and numerical simulation
复制标题
湖泊和水库中的进积砂泥三角洲。
DOI：
--
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
G. Parker
中科院分区：
文献类型：
--
作者：
S. Kostić;G. Parker
河流在到达死水的地方，即湖泊或水库，都会沉积三角洲。这里考虑的情况是沙床河流携带泥沙作为冲刷负荷。一般而言，砂岩倾向于向外沉积，形成河流顶部和雪崩前积层，而泥浆倾向于以底部沉积形式沉积出来。在洪水期间，许多砂床河流携带足够高浓度的冲刷负荷，使河水比静止水体的水更重。在这种情况下，多泥的河流FOW突然下沉，形成底部浑浊水流。在一篇配文中，提出了一个进积三角洲的一维数值模型。在该模型中，河流流沉积、雪崩流沉积和浊流沉积都通过移动边界形式联系在一起。在这里，该模型与两个三角洲进积实验进行了比较。实验表明，模型的三个要素之间存在有趣的相互作用，前缘进积掩埋了底部，并将其上游点一直推向下游，而底部沉积抬高了前缘的脚趾，因此随着沙子从顶部输送，前积的进积速度加快。配文的数值模型只需对输入参数进行最少的调整即可捕捉到这种相互作用。由此得到的三角洲地貌动力学描述与在美国科罗拉多河三角洲观察到的非常相似，在那里它到达米德湖。
Rivers deposit deltas wherever they reach standing water, i.e. a lake or reservoir. Here the case of a sand-bed river carrying mud as wash load is considered. In general the sand tends to deposit out to form a fluvial topset and an avalanching foreset, and the mud tends to deposit out as a bottomset. During floods, many sand-bed rivers carry sufficiently high concentrations of washload to render the river water heavier than that of the body of standing water. In such a case the mud-laden river fow plunges to form a bottom turbidity current. In a companion paper a 1 -D numerical model of a prograding delta was presented. In this model fluvial, avalanching and turbidity current deposition are all linked in terms of a moving boundary formulation. Here the model is compared against two experiments on delta progradation. The experiments reveal an intriguing interaction between the three elements of the model, with foreset progradation burying the bottomset and pushing its upstream point ever downstream, and with bottomset deposition raising the toe of the foreset, so increasing the rate of foreset progradation as sand is delivered from the topset. The numerical model of the companion paper captures this interaction with a minimum of adjustment of input parameters. The resulting description of delta morphodynamics is very similar to that observed in e.g. the delta in the Colorado River, USA where it reaches Lake Mead.