废弃的黄河三角洲的地貌特征及演化

MORPHOLOGICAL FEATURES AND EVOLUTION OF THE ABANDONED HUANGHE RIVER DELTA

本文通过对废弃的黄河三角洲北部沿岸的潮滩和附近海域的地形、地貌对比研究，认为废弃的黄河河口沙嘴，废弃５０年后仍处于侵蚀状态，河口附近海域３０─４０年后己无明显侵蚀。钓口附近海域经５０年冲蚀，目前已不具备水下三角洲的地貌特征，但─１５ｍ以上仍处于侵蚀状态，侵蚀强度随水深增加而减小。－１５ｍ以下已无侵蚀作用。

The Huanghe River is one of the longest rivers in the world.Its progradational delta is quickly growing,but the abandoned river delta suffers clear erosion , especially in the near-coast and coast area,This paper is based on data of investigation and studies on the morphological features and evolution in the north part of the modern Huanghe River Delta coast。The mouth sandspits of the abandoned delta are eroded evidently.There are scarps and muddy bodies near the high tidal line,The erosion or accumulation is much slower between river mouths,so a levelling process happens in the coast。The sea area near the abandoned river mouth is in the erosional condition since 30 years。The erosion decreases downward from zero meter line。 During 1976-1980,isobath of 5m moved 2.6km landward and that of 10m moved 1.81km landward.Compari- son shows that isobaths of 2m, 5m, 10m and 13m in 1985 became 4m,3m,2m and 1m deeper respectively in 1992.There is no clear scouring at water depth of 15m。According to investigations,erosion is not evident in the sea area near the aban- doned river mouth after 30 40 years of abandonment,but coastal sandspits are still in the condition of erosion even after 50 years of abandonment.Hydrodynamic environment is very complex both in the sea area and in tidal bank of the abandoned Huanghe River Delta,so still research should be continued。We should pay special attention to storm surge which can cause violent erosion。