摘要:
研究区位于1964～1976年黄河由刁口流路入海时形成的三角洲潮坪.为进行石油开采在潮坪上构筑的交通设施对波浪形成了良好的屏障,水动力条件具有显著差异的屏障两侧潮坪是研究潮坪特征对水动力条件响应的天然实验场所.在屏障两侧各选择一典型区,实测地貌形态,取样品进行粒度成分分析,根据实测资料分析确定潮坪分形特征.发现水动力环境的强弱决定着潮坪的形貌、沉积物粒度分维值的变化规律.水动力环境强的一侧潮坪滩面分维值高,且随着初始计算网格宽度增大迅速降维;表层沉积物粒度分维值小,且离散性大.相反,在另一侧潮坪滩面分维值低,且随着初始计算网格宽度增大分维值无显著变化;表层沉积物粒度分维值高,且具有较好的一致性.当初始计算网格宽度增大到某个值时,两侧潮坪形貌分维值渐趋一致.在屏障两侧各沿一条与屏障大角度相交的测线取样,并各选择一点采取不同深度的样品做分析计算,发现在水动力条件弱的一侧,样品的粒度分维值表现为远离屏障逐步降维、随深度增加分维值增大的规律;相反一侧粒度分维值变化的规律性很不明显.讨论了水动力环境对潮坪分形特征影响机理.
Abstract:
The research area lies in the subaqueous delta that the Huanghe River entering the sea is formed vis Diaokou between 1964 and 1976.One well field road was built for exploring petroleum which formed a seawall favorably obstructing waves.The hydrodynamic conditions of the north side of the road are relatively violent,on the contrary,that of the south side of the road is nearly placid,which makes the research area a natural laboratory fog studying the influence of the hydrodynamic conditions on the fractal characteristics of the tidal flat.Selecting a area named Case 1 on the side of strong hydrodynamic conditions,and a area named Case 2 on the other side.Measuring the topography and sampling,and analyzing the granulometric compositions,it is found that the hydrodynamic conditions have fatal influence on the surface fractal dimensions and the granulometric fractal dimensions of the research area.In Case 1,which has the strong hydrodynamic conditions,the surface fractal dimensions are obviously larger than those of Case 2 and the granulometric fractal dimensions are relatively smaller than those of Case 2,the surface fractal dimensions of Case 1 decrease quickly with the increase of grid size; the granulometric fractal dimensions are disperse,while the conditions of Case 2 are just reverse.A sampling line and a sampling point in depth on each side of the road are selected.It is found that in the south side of the road the granulometric fractal dimensions change regularly in the line and in depth,the more far from the road the smaller the fractal dimensions,and the more deep the sampling position is the larger the fractal dimensions.While the north side of the road has no this orderliness.The mechanism of the influence of hydrodynamic conditions on the fractal charateristics is discussed.
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