Study On The Response Of Incoming Water/Sediment Variation Characteristics And Coastline Change In Yellow River Delta To Water-sediment Regulation

The Water-Sediment Regulation(WSR) has significantly changed Incoming Water/sediment Variation Characteristics in Yellow River, in order to explore the mechanism of influence on Incoming water/sediment variation characteristics and coastline change in Yellow River Delta(YRD) posed by WSR, this research collected hydrological data of several main hydrometrical stations along Yellow River spanning from 1951-2014. And 58 remotely sensed images of YRD in 25 years in normal periods(NP) in 1986-2001 and water & sediment regulation periods(WSRP) in 2002-2015 are also selected. By using GIS and RS technologies, coastal lines of YRD are extracted and analyzed together with hydrological data to reflect the temporal and spatial change for disclosing the water & sediment regulation effect in recent years. The results show that,(1) the water/sediment characteristics of NP and WSRP show quite different variation patterns. The annual mean volume of runoff in NP is 30% higher than that in WSRP, while the annual mean sediment runoff in NP is 57.4% lower than that in WSRP, sediment concentration in NP declined by 67.3%, 74% than in WSRP respectively. Proportional relationship between water and sediment gets considerable improvement in NP. WSR enhanced the river dynamic of Yellow River, as downstream channels gets scoured, which ends the long-existing phenomenon that the downstream channels always get deposition. WSR reduces the annual fluctuation of incoming water/sediment, and the proportion difference of water and sediment in flood season and non-flood season. As a result, evenness of the monthly water and sediment distribution is improved. Concentration ration of water and sediment distribution within a year in NP are 0.031 and 0.109 lower than that in WSRP respectively.(2) Coastline of YRD in both NP and WSRP show the main trend of erosion, while the retreat rate in NP is approximately 3 times as that in WSRP. Annual net increase of land area during time span of WSR in each year in NP is 8.57 km2, which is much higher than that of the annual average, and the division of siltation and erosion is near to that of WSRP. The Yellow River Estuary(YRE) shows a weak trend of erosion in NP, but area of YRE shows an annual mean net increase of 9.78km2 during time span of WSR in each year in NP. Annual mean area of land erosion during time span of WSR in each year in NP shows a high correlation with the annual mean degradation of downstream channel, and correlation coefficient between them reaches 0.681, at confidence coefficient of above 95%. This indicates that as the river dynamic of Yellow River enhanced by WSR, incoming sediment of YRE is transported further into the sea, which to some extent weakens the siltation in YRE.