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水库联合运行对于库下河道的影响是河流地貌学近年来的热点问题,如何定量表征河道的因应调整则是其难点所在。基于同水位河道过水断面形态参数变化率分析方法,针对黄河内蒙古河段磴口、巴彦高勒、三湖河口、头道拐4个水文站,利用刘家峡水库、龙羊峡水库联合运行之前的1978-1982年、之后的2008-2012年汛期前后实测断面资料,计算了相应年份上述各站同水位下的河道断面面积、水面宽、平均水深等特征参数在经历汛期冲刷后的变化率。结果表明,每年在经历汛期洪水冲刷之后,上述形态参数总体上以增大为主,变化率为正值;大型水库联合运行之前与之后的两个时期相比,同水位下河道断面面积、水面宽和平均水深的变化率分别减小了3.4、3.5和2.8倍。过水断面形态参数的沿程空间变化也由之前的上凸形曲线变为之后增减相间的“S”形曲线。其原因在于,大型水库联合运行削减了洪峰流量、降低了汛期最大流速,从而导致洪水造床能力显著变弱,河道断面形态参数的变化率因之显著减小。大型水库联合运行使黄河内蒙古河道明显萎缩,这不利于可能遭遇的极端大洪水的安全行洪,因此,需要合理利用这些水库的调节功能,有效控制汛期总水沙量和洪峰流量,避免因过度调节而使河道持续萎缩,为可能出现的极端大洪水的安全行洪创造条件。
The joint operation of reservoirs has a great influence on the river courses in the reservoir. In recent years, the impact of river geomorphology has become a hot issue. How to quantitatively characterize the response of the river courses is the challenge. Based on the analysis of the rate of change of morphological parameters of the cross-section of the waterway at the same water level, four hydrological stations at Qiaokou, Bayanjale, Sanhu Estuary and Dao Shuiui of the Yellow River in Inner Mongolia were studied. Before the combined operation of Liujiaxia and Longyangxia reservoirs, 1978-1982 and the data of the measured sections before and after the flood season from 2008 to 2012 from 2008 to 2012 were used to calculate the rate of change of the characteristic parameters such as river section area, water surface width and average water depth after scouring in the flood season in the corresponding years. The results show that the above morphological parameters are mainly increased and the rate of change is positive after flooding in the flood season each year. Compared with the two periods before and after the large-scale reservoirs were operated, the cross-sectional area of the river channel, water surface The change rates of width and average water depth decreased by 3.4, 3.5 and 2.8 times respectively. The spatial variation along the cross-section of the cross-flow section morphological parameters is also changed from the previous upper convex curve to the later “S” curve. The reason is that the joint operation of large reservoirs reduces the peak flow and reduces the maximum flow velocity in flood season, resulting in the remarkably weaker capacity of flood-fighting and the decrease of the rate of change of shape parameters of river sections. The joint operation of large reservoirs has caused a significant shrinkage of the river channels in the Yellow River in Inner Mongolia, which is not conducive to the safe floods of the extreme floods that may be encountered. Therefore, it is necessary to make rational use of the regulation functions of these reservoirs to effectively control the total water flow and flood peak flood season, The regulation will keep the river channel shrinking continuously, which will create the conditions for the safe flood-driving of extreme floods that may occur.