黄河流域代表水文站径流和降水量变化的初步分析

通过对1995—1990年共36a黄河上游和中游两个代表站径流量和区域降水量资料的季节和年际变化趋势的分析，初步揭示了黄河不同流域降水量和径流量之间的关系，发现虽然黄河上游区域平均降水量距平的变化在夏季和秋季呈下降趋势，但代表黄河上游的兰州水文站径流量在夏季和秋季却呈现出明显的上升变化趋势，而黄河中游区域平均降水量距平的变化在夏季和秋季呈下降趋势，代表黄河中游的花园口水文站径流量在夏季和秋季也呈现出明显的下降变化趋势。因此，在比较长时间的气候趋势上，黄河中游地区径流量异常与降水量异常变化趋势是一致的，降水量异常是影响径流量异常的主要因子。而在黄河上游地区径流量异常与降水量异常变化趋势并不一致，降水量减少的同时径流量却增加，这可能与伴随着降水量减少的全球增暖所引起的高原冰川和积雪融化等因素有关。因此，影响黄河上游径流量的因素除了降水等自然因子外，其它因子诸如上游的径流量、人类活动、全球增暖等也同样会影响黄河上游的径流量。

ANALYSIS OF RUNOFF AND PRECIPITATION AT REPRESENTATIVE HYDROGRAPHIC STATIONS ALONG THE YELLOW RIVER

The interannual variations and their trends of regional mean precipitation and runoff at two representative hydrographical stations along the Yellow river,i.e.Lanzhou and Huayuankou,during 1955-1990,and the relationship between runoff and precipitation in different regions have been analyzed in this paper.It is found that the runoff anomaly has the opposite varation trend with precipitation in the upper reaches of the Yellow river,and same in the middle reaches of the Yellow river.This result indicates that precipitation anomaly is a major factor affecting runoff anomaly at a long time scale in the middle reaches of the Yellow river,whereas in the upper reaches of the Yellow river,other factors such as human agricultural activities,snow melting associated with global warming in the source region of the Yellow river,also influence the runoff of the Yellow river.