摘要
本文利用无定河实施水土保持措施前11年(1959-1969年)的日平均流量和日平均含沙量资料,计算了无定河及其支流共12条河流的有效输沙流量。由于流量之间的不连续性,首先将各站所有的流量分为两组:小流量级和大流量级。将小流量级别的流量分别以该流量级的1、3/4、1/2、1/4标准差为间隔进行分级。对于大流量,如果相邻的流量差在对应的小流量间隔内,将其归为一级。然后计算每级流量的输沙量,最大输沙量对应的流量为有效输沙流量。结果发现风沙区河流的有效输沙流量与黄土丘陵沟壑区和河源梁峁沟涧区河流的有效输沙流量之间存在着很大的区域差异。在四种分级间隔下,黄土丘陵沟壑区和河源梁峁沟涧区河流的有效输沙流量一般均出现在大洪水流量范围内,风沙区河流的有效输沙流量出现在小流量范围内。流量分级间隔的大小对风沙区河流的有效输沙流量的历时百分比有着较大的影响。不同地貌区域河流有效输沙流量的差异主要与流量过程和含沙量有关。
Effective Discharge is one of the most important paradigms in fluvial geomorphology which is frequently used to characterize river restoration design and ecological evaluation. Many researchers have dedicated to demonstrate that effective discharge has a regular recurrence interval of 1-2 years. However, some researches show that this is not always suitable for every stream. Hence, further studies are necessary to figure out how the effective discharge behaves. Based on the mean daily discharge and mean daily suspended sediment data during the period of 1959 - 1969 in Wuding River basin, the effective discharges for suspended sediment transport in ten streams were computed using S.3S/4,S/2,S/4 （S denoting standard deviation of discharges in the range of low flows） as class intervals. The results indicate that the effective discharge varies in different geomorphologic regions. In gullied hilly loess region and gullied valley loess region, the effective discharge is in the range of high flows whose flow duration is mostly less than 1%. However, in aeolian region, the effective discharge for suspended sediment transport occurs in the range of low flows with flow duration of about 26% - 30%. For the smallest class interval, the effective discharge propagates to have regular flow duration, with the values of 0. 026% in gullied loess regions and 28 ± 2% in aeolian region. By comparing the results derived from different size of class intervals, the effective discharge for suspended sediment transport in aeolian region appears more sensitive to the size of class intervals. Hydrologic regime and suspended sediment concentration play an important role in the determination of effective discharge and may cause a bimodal dominant discharge. Both normal frequent flows and rare floods can be considered as dominant discharges.
出处
《泥沙研究》
CSCD
北大核心
2010年第3期73-80,共8页
Journal of Sediment Research
基金
国家自然科学基金项目(40788001
40677019)
关键词
无定河
有效输沙流量
水流历时
流量分级
流量过程
高含沙水流
effective discharge
class intervals
flow frequency
flow regime
suspended sediment concentration
Wuding River
