Recent changes in sediment delivery by the Huanghe (Yellow River) to the sea: Causes and environmental implications in its estuary
Recent changes in sediment delivery by the Huanghe (Yellow River) to the sea: Causes and environmental implications in its estuary
复制标题
DOI：
10.1016/j.jhydrol.2010.07.030
复制
发表时间：
2010-09-24
影响因子：
6.4
通讯作者：
Yang, Zuosheng
中科院分区：
文献类型：
--
作者：
Wang, Houjie;Bi, Naishuang;Yang, Zuosheng
60年来，气候变化和人类活动改变了黄河流域的水系。特别是，流域内大型水库的建设和土壤保持措施使流入海洋的泥沙通量减少了近 90%，并增加了流入海洋的悬浮沉积物的粒径（中值粒径现在为 30 微米，而以前为 18 微米）。下游河道的冲刷，为中游黄土地区的泥沙来源增添了新的泥沙来源。中游下游端的小浪底水库修建之前，入海前最后一个水文站利津站在汛期的悬浮泥沙浓度足够高（>35 kg/m(3)），足以抵消淡水与环境海水的密度对比。因此，汛期沿河口水下斜坡发育异重流。黄河口附近的两艘巡航船（一艘在小浪底水库调度之前和一艘在小浪底水库调度之后）的观测表明，由于排海悬浮沉积物的浓度和粒度发生了巨大变化，河口出现了浮力的低重羽，而不是异重羽。入海泥沙的急剧减少和悬浮泥沙粒径的增大，不仅改变了河口泥沙的扩散格局，也改变了岸线和水下坡度。流域气候变化和人类活动的影响已沿着水文路径传递至河口和三角洲，改变了河口沉积动力学和三角洲形态。黄河是气候变化和人类活动背景下流域与沿海地区相互作用的一个说明性例子。 (c) 2010 Elsevier B.V. 保留所有权利。
Over the past 60 years, climate change and human activities in the Huanghe (Yellow River) basin have changed the river system. In particular, construction of large reservoirs and soil-conservation practices within the river basin have reduced sediment flux to the sea by similar to 90% and increased the grain size of suspended sediment delivered to the sea (30 mu m now versus 18 mu m before in median grain size). Scouring of the channel in the lower reaches has added a new sediment source to those derived from the loess region of the middle reaches. Before construction of the Xiaolangdi Reservoir at the downstream end of the middle reaches, suspended sediment concentrations at station Lijin, the last hydrographic station before the river enters the sea, were high enough (>35 kg/m(3)) in the flood season to offset the density contrast between freshwater and ambient seawater. Thus, hyperpycnal flows developed along the subaqueous slope at the river mouth during the flood season. Observations from two cruises near the Huanghe river mouth, one before and one after the operations of the Xiaolangdi Reservoir, suggest that buoyant hypopycnal plumes, rather than hyperpycnal plumes, have occurred at the river mouth since the dramatic changes in concentration and grain size of suspended sediment discharged to the sea. The rapid decrease of sediment discharge to the sea and the increase of grain size of suspended sediments not only changed the sediment dispersal pattern at the river mouth, but also modified the shoreline and subaqueous slope. The effects of climate change and human activities in the river basin have been transferred along the hydrological pathway to the estuary and delta, and have changed estuarine sediment dynamics and delta morphology. The Huanghe presents an illustrative example of river basin-coastal zone interactions in the context of climate change and human activities. (c) 2010 Elsevier B.V. All rights reserved.