关键词: 黄河源区, 径流, 年内分配

Abstract: Annual runoff distribution is connected with the flow recharge situation.With the impacts of climatic changes and increasing density of human activities, the hydrological regimes have been changed,including changes of annual runoff distribution, which may show effects on water resources management and ecological health.In this paper, indexes of unevenness, concentration, and variation have been defined and calculated according to gauge records of runoff in the last half-century.And then the changes of annual runoff distribution in the headwater of the Yellow River have been discussed.The results show that: 1) the annual runoff distribution in 1990s was quite similar to that of 1970s, while 1980s was almost the same to 1960s; 2) in 1990s, the annual runoff distribution had changed a lot, mainly because of runoff decrease in the wet season (July to Oct.); 3)Maqu station, which locates at the upper reaches, has a higher unevenness, concentration and relative variation rate but a smaller absolute variation rate than that of the Tangnaihai station.It should be noted that the indices used in this paper have correlations between each other, but have reflected the characters of annual runoff distribution by different ways.For further research, it is necessary to develop more suitable indices to describe the essence of the annual flow regime.The causes and effects of annual runoff distribution changes are all important issues for research considerations.

Key words: annual distribution, headwater of the Yellow River, runoff