No linear relation, however, could be extracted between the released water discharge and flux of scoured sediment. In short, changing WSM regimes cause the flux of Huanghe material to the sea to be irregular. Water consumption in the lower basin during WSM is an important

factor influencing transport of water and sediment in the lower reaches. A considerable part of released water from the Xiaolangdi dam during WSM was diverted for irrigation of farmland and wetland (shown in Fig. 6). Since 2006, the scouring effect during WSM has been decreasing (shown in Table 5), primarily due to the coarsening GDC-0199 research buy sediment in the riverbed and water consumption (Chen et al., 2012b). The history of the Huanghe is a story of frequent diversions and catastrophic floods. The central conundrum for the Huanghe is sediment. As discussed above,

the construction of the four large dams has had a positive effect on flood control and riverbed morphology in the lower reaches. Sediment infilling in the Sanmenxia reservoir has been alleviated through the WSM, and 7.15 × 108 m3 (7.4% of impoundment capacity) of sediment was flushed during 2002–2010. WSM can also temporally mitigate the rapid infilling of sediment Rigosertib in the Xiaolangdi reservoir, yet it is still losing its impoundment capacity at a high rate. The net effect is that sediment in the Sanmenxia reservoir was transferred to the Xiaolangdi reservoir, but only a small fraction of the sediment could be delivered to the lower reaches. The so-called triumph of Xiaolangdi dam in flood control and river-bed scouring comes at the cost of rapid infilling of sediment behind the Xiaolangdi dam. When projected to the future, a central problem will be finding a location for sediment when the Xiaolangdi reservoir eventually loses its impoundment the capacity. In addition, successive riverbed scouring had increased the transport capacity of the lower Huanghe from 1880 m3/s in 2002 to ∼ 4100 m3/s in 2012, which greatly reduces flood risk in the lower basin. The scouring capacity

has been weekend gradually since 2006 by the coarsening riverbed sediment, however, because the finer sediment has been preferentially transported downstream (Chen et al., 2012b). The possibility does exist that sediment again begins to accumulate in the riverbed of lower reaches, as it did before the construction of the Xiaolangdi dam. Because the riverbed of the lower reaches was either a sink or a source for the Huanghe sediment in history. The recent changes in riverbed scouring imply that the Huanghe sediment delivery to the sea will also change correspondingly. The Sanmenxia and Xiaolangdi reservoirs on the Huanghe provide prime examples of sediment entrapment behind dams. Large dams in the world also trap sediment at varying levels.