黄河上游兰州至头道拐河段流量频率变化分析

Analysis on discharge frequency change in the Lanzhou——Toudaoguai reach of upper Yellow River

根据兰州至头道拐河段出口站年径流量与河段年入汇径流量之间的双累积曲线关系,建立了年径流量双累积曲线(DMC)模型,提出了头道拐站天然年径流量的还原计算方法与步骤,并通过采用累积频率分析法对头道拐站天然年径流量还原值进行了丰平枯划分。分别对头道拐站1956-1967、1968-1986及1987-2004年各时段流量频率分布进行了统计分析。结果表明,随着时段的发展,小流量频率有逐渐增大的趋势,而大流量频率有逐渐减小的趋势。其中,1968-1986年流量频率变化主要是由人类活动(包括水库调蓄、河道引水等)引起的,1987-2004年小流量频率增大主要是由人类活动引起的,而大流量频率减小主要是由于天然年径流量减少、枯水年份增多造成的。

A double mass curve model （DMCM） of runoff analysis is presented using a relationship of inflow versus outflow runoffs in the Lanzhou -- Toudaoguai reach of the upper Yellow, and a method for runoff revert calculation is described. The natural runoff at the Toudaoguai station was divided into three categories, high, medium and low flows, using cumulative frequency analysis method, and statistics method was used to find the distribution of discharge frequency for the periods of 1956-1967, 1968-1986 and 1987-2004. The results show that the frequency of low flows increases with time while the frequency of high flows decreases. The change in frequency distribution in 1968-1986 was primarily caused by human activities such as reservoir regulation, water diversion and so on. In 1987-2004, the frequency increase of low flows was mainly caused by human activities while the frequency decrease of high flows by nature runoff reduction.