Study On The Influence Of Water And Sediment In The Yellow River On The Delta Front

The Yellow River delta,one of the three famous deltas in china,is a fan-shaped alluvial plain of the Yellow River,which is formed by the accumulation of a large amount of sediment accumulated near the mouth of the sea.It is located in Shandong Province.The Yellow River is the lifeline of the Yellow River Delta,Its runoff and sediment volume have significant influence on the coastline change,wetland area change,vegetation landscape and land use change in the Yellow River Delta This paper takes the Yellow River delta front(modern Yellow River delta)as the study area supported by the National Natural Science Fund Project(41371517),Shandong province science and technology plan(2013GSF11706)project.And Through field investigation and collectin experimental data,combined with the study area time scale(1973-2016),the amount of sediment runoff of Lijin station the hydrological data(1977,1981,and 1986,1991,1996,2001,2006,2011 and 2016)a total of 9 LANDSET images,and by means of SPSS,Eview,ENVI,Arc GIS and other professional software,analysis the change law of water and sediment flux and its two relations in the lower reaches of the Yellow River,delta front,shoreline wetland area,vegetation landscape characteristics of land use change type,and the relationship between the Yellow River Delta and the Yellow River sea frontier wetland sediment.(1)The runoff of the Yellow River has obvious seasonal variation.The average years of flood discharge is 12 billion 748 million cubic meters,accounting for 60% of the annual average runoff;the overall trend of the Yellow River runoff is decreasing,runoff decreased year after year,and At the same time,in 1979 and 1985,it can be divided into three periods: drought,abundance and drought..The mutation point of runoff is 1985 in the Yellow River.And the trend tests of annual runoff,flood season,non-flood season runoff were significantly reduced.(2)The sediment load of the Yellow River sea has obvious seasonal variation.For many years the flood season average sediment discharge was 397 million T,accounting for 87% of the average annual sediment load,The general change of sediment carried by the the Yellow River is decreased,sediment yield decreased year after year,At the same time in 1985 and 1996 as the boundary it can be divided into sandy-sand-sand less three stages.The mutation point of the Yellow River sea mud the sediment is in 1991,The trend tests of the annual sediment discharge and the non flood season are also significantly reduced.(3)The coastline of the the Yellow River Delta has increased by 87783.84 m,the growth rate of 2194.59m/a.The diversion of the Yellow River has the most direct impact on changes in the coastline.In 1976,the Yellow River river was changed into a clear channel from the Diaokou River,and the Diaokou river began to retreat.The coastline of the Qingshui River began to extend to the sea.In 1996,the clear channel was changed into 8 Branch mouth,clear water shoreline began to retreat,clear the development of the 8 branches.(4)The general characteristics of area change in front wetland of the Yellow River Delta is that the wetland area of Diao river is gradually less.After the diversion of the Yellow River,the wetland area of Qingshui flow path began to increase,and form a new delta wetland.after 1996,due to the artificial interception,the Yellow River into the sea from 8 Branch mouth,and the wetland area changes of the Yellow River delta began to extend northward.Due to the impact of Marine erosion is more important than sedimentation in the Yellow River,the wetland of the Qingshui flow path began to degenerate and Back to the Inland.During the 1977-2016 year period,the wetland area of the the Yellow River Delta has decreased by 85719.06 hectares,and total area increased by 118116.29 hectares,the efficiency increased by 2952.91hm2/a,net land 32397.23 hectares,land reclamation rate is 809.93hm2/a.(5)The land use of wetland landscape in the Yellow River delta was transferred out 78129.54hm2,including beaches,saline land and unused land transferred most.The unused land and tidal flat were transferred out of 36747.84 km2 and 33727 km2 respectively,accounting for 80% and 95% of the total amount of land and unused land in 1977,respectively.The area of cultivated land was transferred to the most,with a new increase of 17458km2.Farms and woodland,salt pan and pond area were also increased,respectively 38842.22 km26815.6 and 3231.52 km2 km2.(6)The correlation of the Yellow River delta wetland area and the length of shoreline respectively and runoff were positively correlated,correlation length is greater than the correlation between the area of coastline,coastline and non-flood season runoff relationship more closely,more contribution.Runoff in the non-flood season also has a great influence on the area of wetland,which contributes more.The correlation between shoreline length and sediment volume was negative,but the correlation between wetland area and sediment volume was positive.The length of the coastline in the Yellow River delta is mainly affected by runoff,and there is a positive correlation between them.The change of wetland area in the Yellow River delta is mainly affected by the amount of sediment.