, 2011). The dam-related processes have also altered the transport of Huanghe material to the sea. The annual WSM scheme has imposed an extreme disturbance on the transport pattern of Huanghe organic carbon, silicon, and phosphorus (He et al., 2010). During the 2003–2009 WSM, large proportions of the annual dissolved organic carbon (35%) and particulate organic carbon

(56%) were transported to the sea. This dam-controlled input of organic carbon has a series of potential impacts on the biogeochemical processes at the river selleckchem mouth and its ambient sea (Zhang et al., 2013). Similarly for the Danube River, dissolved silicate load of the river had been reduced by about two thirds since dam constructions in early 1970s, which resulted in a series of environmental problems in the Black Sea (Humborg et al., 1997). The construction of Three Gorges Dam has potential impacts on the ecosystem in the Yangtze estuary and coastal waters where eutrophication and harmful algal bloom frequently occur.

The Yangtze River is estimated to lose a considerable proportion of its annual nutrient (in particular phosphorous and silicon) flux to the sea (Wang and Uwe, 2008), primarily due to dam-related processes. For the Mekong River, the trapping of nutrient-rich sediment by dams would potentially lead to decline in agricultural productivity and loss of agriculture land in the Mekong river delta. The damming of large rivers has therefore received both positive and negative feedbacks. learn more As stated by Milliman (1997), river damming is a double-edge sword. The four large dams on the Chinese Huanghe have altered its water and sediment fluxes, suspended sediment concentration, grain sizes, and inter-annual patterns of water and sediment delivery to the sea. In detail,

the dam effects on the Huanghe can be summarized as follows: (1) The four large new dams modulate the river flow between wet and dry seasons. Flow regulations lead to increases in water consumption over the watershed, a dominant cause for decreasing Huanghe material to the sea. Huanghe water discharge to the sea now relies heavily on Xiaolangdi releasing practices. Damming of the Huanghe has received both positive and negative feedbacks. Infilling of sediment behind the Xiaolangdi dam remains high and riverbed scouring began to weaken after 2006. It will be a big problem finding a location for the sediment when of the Xiaolangdi reservoir eventually loses its impoundment capacity. The Huanghe provides an example of management issues when large dams eventually lose their impoundment capacity. This study is jointly funded by the Youth Foundation of State Oceania Administration, China (No. 2010309) and the National Special Research Fund for Non-Profit Sector (No. 200805063 and No. 201205001). We gratefully appreciate the chief editor and the anonymous reviewers for their helpful comments which improved the manuscript.