【摘要】 以往在黄河三角洲沉积量的估算中 ,对沉积物干容重和计算边界等问题不够重视 ,导致计算结果存在明显出入。本项研究通过广泛收集资料和大量采样分析得到了多种沉积环境下沉积物干容重的计算模型 ,结合三角洲沉积结构分析和利用地形测量数据 ,计算了黄河口钓口河流路时期亚三角洲不同时期的沉积量。其中 196 5年至 1974年间钓口河亚三角洲前缘坡脚以内的总淤积量为 71. 0亿t。其平均干容重为 1. 36g/cm3。这一干容重用于估算其它亚三角洲沉积量不会造成明显误差。认为忽略三角洲下松软沉积层的压实沉降、三角洲平原相和前缘相中粘性土与非粘性土干容重的差别以及来沙量的测量误差对计算结果影响较小。更多还原

【Abstract】 Sediment dispersal at the river mouths has been an important topic in the fields of geomorphology and hydraulics for a long time and estimating sediment budget of the deltas is a principal method for quantifying the sediment dispersal system at many river mouths. Many reports about sediment dispersal at the Yellow River mouth have been given previously using this method. However, since the dry bulk density of deposits in the delta and the boundaries set for calculating the volumes of deposits did not receive a proper treatment, big discrepancy existed between estimates of sediment budgets of the delta provided by the previous studies.Considering the effects of grain size composition, burial depth, and exposure conditions on the dry bulk density of deposits and based on abundant data about the dry bulk density of deposits in the delta, this study defined the dry bulk densities for the deposits in the delta plain and buried delta front deposits, buried prodelta, exposed subaqueous prodelta, and newly deposited top 1 m layers on the delta front. Combining the constructed models of dry bulk density for different depositional settings with the results of analyzing the sedimentary framework of the delta, sediment budgets at Diaokouhe lobe of the Yellow River delta were calculated. The foot of the delta front slope was set as the outer margin of area for defining the sediment budgets. This margin is of geomorphologic significance and is easy to be located on the surface of delta recorded by the bathymetric data. Results show that sediment deposited in the delta plain and front of the Diaokouhe lobe over the period from 1965 to 1974 was about 7.10×10 9 tons, accounting for 73.5% of the incoming sediment. Errors resulting from ignoring clay layers in the deposits on delta plain and front, consolidation of soft layers underlying delta deposits, and deviations in records of the incoming sediment were proved to be about 2.6% for the percentage of sediment deposited in the delta, suggesting the higher reliability of the sediment budgets given by this study. From the mass and volume of sediments deposited in the Diaokouhe lobe over the period of 1965 -1974, a mean dry bulk density of 1.36 g/cm 3 was acquired. On account of the dominance of silt in the deposits of the delta, it seems to be an appropriate approximation of the mean dry bulk density for the deposits in the other lobes of the delta.更多还原