以沂河流域为研究区,运用水文特征参数时间序列法,分析1951-2002 年流域降水、径流、洪峰流量等水文要素的演化趋势,通过临沂站50 年来天然径流过程的回归模拟及其与实测径流的比较,定量分析气候变化和人类活动对径流的影响。结果表明：近50 年来沂河流域年径流量和各月径流量显著减少,并且对降水波动的响应迟缓,而单次暴雨径流对降水反应敏感;10 年尺度的降水波动中,径流随着降水的多少而发生相对一致的变化趋势,降水变化在一定程度上控制着径流的演化;但是20 世纪60 年代中期以来,临沂站实测径流的平均值减少了149mm,占天然径流量年平均值的51.6%,气候变化和人类活动对径流减少的贡献率分别为39.3%和60.7%。水利工程建设、土地利用变化、水资源开发利用等人类活动对径流产生更为深刻的影响。流域可持续发展要求在遵循水循环自然规律的基础上合理约束人类活动。

Taking the Yihe River basin as a study region, this paper analyzes the variations of hydrological characteristics such as precipitation, runoff and peak discharge, during the period 1951-2002. Time series analysis methods, such as the Kendall method and orderly cluster analysis are used to test the change trend and the mutation of precipitation-runoff. The influences of climate change and human activities on runoff were examined quantitatively based on the comparison between the observed runoff and regression simulation data of the natural runoff at Linyi hydrological station. Some conclusions are drawn as follows. (1) During recent 50 years, the Kendall test value of the annual precipitation is -1.028 at Linyi hydrological station, showing that the precipitation decreased slightly. However, the value of annual runoff is -3.689, decreased evidently, and monthly runoff shows the same trend. That is the responses of runoff to precipitation tend to be weak. But the change trend of rainstorm runoff shows that single storm-runoff keeps strong consistency with rainfall. (2) Based on the runoff mutation, the annual precipitation-runoff process can be divided into three periods, 1951-1964, 1965-1975, and 1976-2002. In the 10-year scale, the observed runoff shows a relatively consistent trend with rainfall. To some extent, precipitation controls the evolution of runoff. (3) Since the mid-1960s, the mean annual runoff at Linyi hydrological station decreased by 148.8 mm, accounting for 51.6% of the mean annual natural runoff. The contribution rate of climate change and human activities to runoff reduction is 39.3% and 60.7%, respectively. The human activities, such as hydraulic engineering construction, land use and land cover change and water resources development, have a profound impact on runoff. The river basin sustainable development requires reasonable constraints to human activities to comply with the nature law of hydrological cycle.