COMPARISON OF MEAN HIGH TIDE LINE AND 2 M ISOBATH REFLECTING EROSION AND ACCRETION OF THE YELLOW RIVER DELTA

The Yellow River delta is one of the areas with the greatest erosion and accretion in China and the world,and its erosion and accretion attract a lot of attention.Two methods for mean high tide lines derived from remote sensing data and 2 m isobaths from field bathymetry data to reflect changes of erosion and accretion were described in detail.Furthermore,remote sensing data acquired on 1 December 1976 and 2 April 1992 and field bathymetry data in 1976 and 1992 covered Diaokou promontory and Qingshuigou promontory,and remote sensing data acquired on 31 May 1996 and 25 June 1999 and bathymetry data in 1996 and 1999 that covered Q_(8) promontory were used in this two methods to reflect area changes of erosion and accretion of Diaokou promontory,Qingshuigou promontory,and Q_(8) promontory,and finally the results from the two methods were compared.The results show that,for Diaokou promontory,Qingshuigou promontory,and Q_(8) promontory,either erosion area,accretion area or net accretion area measured by mean high tide lines are evidently smaller than those by 2 m isobaths.We believe that mean high tide line and 2 m isobath are different indicators in indicating changes of erosion and accretion of the Yellow River delta.But they are complementary: mean high tide lines derived from remote sensing data indicating changes of subaerial delta and field bathymetry data indicating changes of subaqueous delta.