Study On Sediment Transport Capacity Of The Sea Near The Yellow River Delta

The sediment transport capacity of the sea near the Yellow River Delta refers to the amount of sediment that is transported outside the test area of the Yellow River Delta each year.The magnitude of the sediment is equal to the annual amount of sediment in the sea near the Yellow River Delta minus the amount of sediment entering the sea.The capacity of sediment transport is the basis for determining the spatial distribution of sediment in the Yellow River estuary,slowing the sedimentation rate of the Yellow River estuary and its feedback effects.However,it is found in the work that there is a large error in the elevation of the topographic survey in the sea area near the Yellow River Delta,which leads to a large error in the amount of scouring and silting in the sea near the delta,which in turn causes a large error in the sediment transport capacity of the sea near the Yellow River Delta.Using the research results discovered by the previous research: in a large area like the Bohai Sea,the simulated tidal level is not sensitive to the terrain test error.Even if the terrain data with large error is used,the simulated tidal level obtained is still correct.To reduce the elevation error of the sea near the Yellow River Delta,this study explores the source of elevation error by using the two-dimensional mathematical model of the tidal flat in the Bohai Sea and the large-scale encrypted topographic data in the sea near the Yellow River Delta in 1992,2000,2007 and 2015.The best time for the future sea area test,revised the fouryear elevation data of the Yellow River Delta in 1992,2000,2007,and 2015,and calculated the Yellow River Delta sea area rush in 1992-2000,2000-2007,and 2007-2015.The amount of silt and the amount of sediment transported to the sea in the corresponding time period.First,the source of elevation error in the Yellow River Delta is studied.The study found that the assumptions used in the test refinement(the measured water level of the deep water survey point is equal to the synchronous observation water level of the test section)can lead to two types of elevation errors.The first type of error: the farther the measuring point is from the shore,the greater the difference between the water level and the shore synchronous water level during the deep water survey,the average difference is about 0.3m,the most is about 0.6m;the second type of error occurs at the shore level.When the observation station is located in the tributary of the tidal flat,when the tidal level of the shallow water in the shore falls to a certain extent,the measured water level at the river is not the tidal level of the shallow water area,and there is a large error between the two,up to 1.3m.Secondly,a method for reducing the elevation error caused by the water level reference assumption is proposed.Based on the principle of minimization of elevation calculation error caused by water level reference assumption,the best measurement period for typical topographic survey sections in Bohai Bay and Laizhou Bay is given.The best test period for the section of tidal flat in Bohai Bay is before high tide and before low tide after high tide.The section measurement of no tidal flat is before,after and after high and low tides;the best test period of the tidal flat section of Laizhou Bay is between low and low tides and high and high tides before and after,and the tidal flat section is Before low tide,before and after high tide.The optimal measurement period is 25%~50% of a tidal period,and the minimum average error of the sea area section measurement is 0.04~0.12 m.Third,the four-year elevation data for 1992,2000,2007,and 2015 were revised.Using the water level results simulated by the Bohai tidal model,the instantaneous water level at each measuring point can be obtained.Using this water level minus the measured water depth,the seabed elevation of the measuring point can be obtained.Using this method,the corrected terrain elevations of 1992,2000,2007,and 2015 were obtained.Using the topographic data of these years,the amount of scouring and silting in the adjacent two sides(1992-2000,2000-2007,2007-2015)was calculated,which were 603 million m3,-440 million m3,and-69.69 million m3,respectively.Finally,the amount of sediment lost to the Yellow River Delta in the corresponding period from 1992 to 2000,2000-2007,and 2007-2015 was subtracted from the amount of sediment in the Yellow River Delta,which was 2.35 billion tons and 1.737 billion tons respectively.1,695 million tons,that is,the annual average amount of sediment transported to the sea is 279 million tons,257 million tons,and 205 million tons.