1919—2010年黄河上中游区径流量变化分析

应用Mann-Kendall秩次相关检验、流量历时曲线法、双累积曲线法等方法对黄河干流陕县站和河口镇站1919—2010年径流量演变过程进行了分析。结果表明:区域面平均降水量趋势性变化不显著，而上游（河口镇站以上）及中游（河口镇—陕县）年径流量自1985年以来呈显著减少趋势，中游径流量的降幅高于上游。黄河径流量变化具有明显阶段性，上游和中游径流量变化都经历了枯水期—丰水期—枯水期3个时期，现在黄河正处于枯水期。采用双累积曲线法，定量分析降水和人类活动对径流量的影响，上游和中游人类活动对径流量减少的影响程度分别占88.1%和84.9%，水利水保工程、生产生活用水等人类活动是引起黄河径流量减少的主要因素。

Temporal changes in annual runoff and influential factors in the upper and middle reaches of Yellow River from 1919-2010

Of the total water resources in the Yellow River, the contribution of surface water accounts for about 84%. However, the surface water status has undergone a significant change during the past nine decades mainly due to the combined influence of climate change and human activities. The study analyses the variability of annual runoff in the upper and middle reaches of the Yellow River. The analysis uses methods of the Mann-Kendall rank correlation test, the flow duration curve and the double mass curve. Observed stream flows for 1919-2010 at the Shanxian and Hekouzhen stations on the river are used for the analysis. Results show that there have been abrupt reductions in the observed annual runoff in both upper (at Hekouzhen) and middle reaches (between Hekouzhen and Shanxian) of the river since 1985, with a slight higher reduction in the middle reach. This is despite the fact that there have been no significant changes in precipitation over the drainage areas for the two stations during the same period of time. Apparent periodicities (low-high-low) can be observed in the variation of annual runoff in both upper and middle reaches of the river. At present, the river is experiencing it low-water period. The analysis of the double mass curve method indicates that human activities are respectively responsible for 88.1% and 84.9% reductions of annual runoff in the upper and the middle reaches of the river. Therefore, human activities appear to be the main influential factor for the change in annual runoff in both upper and middle reaches of the Yellow River.