中文摘要：

针对三峡工程蓄水后下游河道河床表面形态的变化,采用分形维数对河床表面形态进行量化,并分析河道冲淤调整特点,对河床表面分形维数（BSD）的变化特点及物理意义进行探讨。结果表明,BSD与河床各个剖面形态之间的关系是整体与部分的关系,BSD能全面地反映床面形态的复杂程度。三峡蓄水后,宜昌-虎牙滩和宜都河段BSD明显增大,关洲河段增大幅度较小,而芦家河河段BSD值略有减小,同时,各河段BSD的变化可在一定程度上表征三峡蓄水后下游河道河床综合阻力的调整结果。可通过对各河段演变趋势的分析,来预测其BSD的变化,进而为分析其阻力和水位的变化趋势提供依据。

英文摘要：

The changes in erosion-deposition patterns of downstream river bed surface after the impoundment of Three Gorges Project（TGP） are quantified by the river bed surface fractal dimension（BSD）.The changing character and the physical mechanism associated with the changes are also analyzed.The study reveals a whole-part relationship between the BSD and each cross-section.The complexity of river bed surface can be well represented by BSD.After the TGP impoundment,there is a significant increase in BSD along the Huyatan and Yidu reaches.While,less increase is found for the Guanzhou reach and the opposite result is obtained in the Lujiahe reach.The change in BSD of each river reach is able to characterize the deformation in the river bed surface,which is resulted from the new regime of integrated frictions after the TGP impoundment.The BSD can thus be predicted through analyzing the trend change in each reach,which provides necessary data for studying the new relationship of bed friction and water level.