Study On Spacial-Temporal Evolution Of Erosion/Deposition Of Yellow River Delta And Trend Forecast

Yellow River delta is located in the connection zone of river and sea, it is the base of energy sources,petroleum and agriculture of Shandong Province. In modern Yellow River delta, land and sea interact intensely, so the study on Erosion-deposition of it plays an important role in the planning and oil exploration of Yellow River delta. This paper is carried out in the background of the project of mechanism and protection of erosion-deposition of Yellow River delta, which is part of National 973 Project of China: "Land-Sea interaction and its effect on the environment in the typical estuaries and coastal seas of China".The paper mainly includes two parts, one part is about erosion-deposition evolution of Yellow River sub-aerial delta, and another part is about erosion-deposition of Yellow River underwater delta. In the part of Yellow River sub-aerial delta, Multi-temporal remote sensing data for 1976 to 2005 were used to examine the changing pattern of erosion and deposition of the modern Yellow River sub-aerial delta. In the part of Yellow River underwater delta, underwater landform data from 1976 to 2004 were used to analyze the Erosion-deposition evolution rules of annual intervals of Yellow River underwater delta. So we encountered some advisable conclusions:(1) From year 1976 to 2004, the area of Yellow River sub-aerial delta increased by 167.0km2 with a mean deposition rate of 6.0km2/a. Partly, from year 1976 to 1996 it increased 245.1km2/a with a mean deposition rate of 12.3km2/a, from 1996 to 2004 it reduced -8.0km2 with a mean erosion rate of -9.7km2/a.(2) Spatially, Yellow River sub-aerial delta can be divided into three regions; they are Diaokou promontory suffering erosion, Qingshuigou promontory with fast deposition and the south region which was stable. Timely, Yellow River sub-aerial delta can be divided to 3 stages; they are year 1986-1985, 1986-1997, 1998-2004, which were fast deposition stage, erosion-deposition adjustment stage and weakness erosion stage respectively.(3) By the relationships between the area changing of Qinshuigou Promontory and water and silt came from Yellow River, we educed when the silt came from Lijin station reaches to 3.3×108t annually, the Qingshuigou promontory keeps erosion-deposition adjustment. And through the EOF iterative methods, it indicates In the stage of year 1976-1996, when the silt and water came from Lijin station reaches 3.04×108t and 102.0×108m3 annually respectively, the Qingshuigou promontory reaches the adjustment state.(4) By the contrast of Yellow River underwater landform data, we found the erosion-deposition mainly focuses surround the current and banded promontories. So, after Yellow River shifted from the Diaokou course to the Qingshuigou course in 1976, it formed 3 erosion centers at Diaokou promontory and a large deposition center at Qingshuigou promontory.(5) The cumulative of silt erosion and deposition in Yellow River underwater delta has a strong relation with the cumulative of water and silt came from Lijin station.