Primary Study Of Sedimentary And Ecological Environments In The Yellow River Mouth Wetland Reserve Area

Wetland of the Yellow River delta is the youngest and the most characterful wetland in the world. The type of wetland is quite rich, and the area change is unstable.We have collected 8 time of Yellow River delta remote sensing data, in order to identify alluvion and erosion of Yellow River delta from 1976 as well as entironment succession in estuary reserve. At present the Yellow River delta wetland is affected by the climatic change, the natural disaster, drying up of Yellow River, the human's activity, sea level rising, coastal erosion, underground sea water invasion, the ecological environment is quite frail. So governmental entities have carried out Yellow River water and sediment regulation from 2002 which depends on the power of nature in order to erode the riverbed ,and it brings the new vitality for the estuary mouth wetland which is an item of great wetland repair project..Based on fieldwork in Yellow River delta and historical data of Yellow River variance, the modern Yellow River delta surface layer deposit environment is divided into 7 deposition areas. In view of 1 deposition area, the further division is 5 sub-areas.We realize that Yellow River mouth wetland deposition system through 3 section planes is composed of deposition of the different time ,and the deposition succession is complex.The TM 3(R)-4(G)-2(B) band combination mode is helpful to obtain the Yellow River delta coastline, the TM 4(R)-5(G)-3(B) band combination mode is helpful to obtain the typy of the Yellow River delta wetland.From 1976 to 2006, the area of Diaokou promontory in north of the Yellow River delta reduced 423km~2 above the low-tidal level, the area of south seacoast reduces 65km~2, and Qingshuigou promontory increased 296km~2.The distance to the Yellow River water and the soil salinity content dominated macroscopic distribution of the estuary wetland protectorate vegetation.Drying up of Yellow River and Yellow River water and sediment regulation play an important role in the typy of the Yellow River delta change.Because of the sixth Yellow River water and sediment regulation in 2007, the riverbed was scoured, the flood carrying capactity was enlarged, the shape of riverbed was adjusted, and the river developed well.In contrast to the actual data ,we estimate that 2600m~3/s is the critical discharge when the Yellow River downstream river course is scoured.from June 30 to July 5 in 2007,about 5.6×107m~3 of bedload and 1.12×10~9 Kg of sand inflooded wetland,which improved the wetland ecological environment greatly.But to at the end of October, 2007, river course siltation situation of Q4 and the C2 cross section improved less slightly than that of water and sediment regulation before, and the Q7 cross section which have already comprehensive backsilted, returned to the original level.