黄河上游径流变化特征及其影响因素初步分析

利用1956—2005年黄河上游水文和气象台站观测的流量、气温、降水资料,用气候诊断方法分析了该地区径流量的年代际演变特征以及影响因子。结果表明：20世纪50—80年代年平均流量呈波动性的上升趋势,90年代至21世纪的前5年年平均流量呈下降趋势。降水量、蒸发量、气温是影响流域流量的主要气象因子,它们的机理完全不同。枯季、雨季降水量与流量分别呈负、正反馈机制,秋季和冬季降水量对次年春夏季的流量有比较明显的调节作用;4—5月（10月）气温与后期5—6月（11月）流量呈负（正）反馈机制;枯季、雨季地表蒸发与流域的河川流量呈负反馈机制,并且消耗的水资源量呈逐年增加的趋势。20世纪90年代以来黄河上游地区河川流量的减少与降水量减少、地表蒸发量增大有关。

Analysis on Runoff Variation Characteristics and Influencing Factors in the Upper Yellow River

Based on the data of runoff, temperature and precipitation observed in the hydrological and meteorological stations in the upper Yellow River from 1956 to 2005, the inter-decadal variation characteristics of runoff and its influencing factors was analyzed by the climatic diagnosis method. The results indicated that the average runoff from 1950s to 1980s showed undulated increasing trend, and that from the 1990s to the first 5 years of 21st century appeared decreasing tendency. The influencing meteorological factors to runoff mainly comprise precipitation, evaporation and temperature, and they have completely different function mechanisms. There exist negative feedback mechanism between runoff and precipitation in dry season but positive feedback mechanism in rainy season. The precipitation in autumn to winter has quite obvious adjusting function to the runoff of spring to summer in the next year. There exist negative feedback mechanism of runoff between May to June and April to May, but positive feedback mechanism of runoff between November and October. In both dry season and rainy season the surface evaporation appeared negative feedback mechanism between surface evaporation and river runoff, besides, the consumption of water resources had an increasing trend year by year. Since 1990s the runoff in the upper Yellow River has decreased tendency, which related with the decreasing of precipitation and the increasing of surface evaporation.