东江下游博罗河段水沙特性

Hydrological and sediment variation of Boluo reach in downstream of Dongjiang River

通过收集东江下游博罗河段历年的水文、地形资料,首先从水沙分配变化和流量水位变化两个方面对博罗水文站的水沙特性进行了分析,然后选取研究河段各历史年份的河床平均高程、深泓、河道整体冲淤和特征断面等研究对象,分析了研究河段的河床异变特性.认为博罗站年平均流量呈微弱增加趋势,而输沙量则总体呈下降趋势;1997年以后的12年间,研究河段河床地形大幅下切,下切幅度自上而下沿程递增,刷深幅度远远超过了此前30多年的变幅,且与河流自然冲淤状态下的冲刷形态明显不同,应为采砂所致,这是本研究河段水沙变异的最主要原因,对本河段的动力条件与河床演变产生了深刻影响.

The hydrological and sediment characteristics of Boluo hydrometric station were analyzed from the change of two aspects both water-sediment distribution and discharge-water level by collecting the historical hydrologic and topographic data in the downstream reaches of Dongjiang River firstly. And then the riverbed variation characteristics of the researched river are studied through the historical changes of the average riverbed elevation, thalweg, scouring and silting in the whole riverbed and the characteristic sec- tions. The results show that the mean annual discharge at the Boluo hydrometric station increased faintly while sediment discharge tended to decrease. During the period from 1997 to 2009, the riverbed topography was enormously deepened; and the deepening amplitude increased from upstream to downstream, which had gone far beyond the previous 30 years and was obviously different to the riverbed natural evolu- tion. The most important reason was the sand dredging, which demonstrated a profound influence on the changes of the hydrodynamic and fluvial processes.