拉萨河流域水循环要素演变趋势分析

采用Mann Kendall秩次相关检验法、线性回归分析等方法对拉萨河流域水循环要素长期变化趋势进行了分析研究。结果表明,拉萨站的年平均气温总体上均呈上升趋势,每10年增加0.33℃,气温上升趋势显著;年蒸发能力总体上均呈上升趋势,但上升趋势并不显著;年降水量长期变化趋势不明显;拉萨站的年平均流量总体上呈上升趋势,但上升趋势并不显著;自2000年以来,拉萨站出现中水年的机会较少,出现丰水年的机会较多且丰枯变化剧烈;拉萨站径流年内分配不均匀系数和7—9月降水量占全年比例年际间较稳定。

Variation trend of water cycle factors in Lhasa River Basin

The long-term variation trend of the water cycle factors in the Lhasa River Basin was analyzed using techniques including the Mann-Kendall test and linear regression analysis. The results show the following： The annual average temperature at Lhasa Hydrological Station presented an increasing trend in general with a rate of 0.33℃ per ten years, and this increasing trend was significant. The annual evaporation capacity at Lhasa Hydrological Station presented an increasing trend, which was not significant. The long-term change trend of the annual precipitation was not obvious at the station. The annual runoff volume showed an increasing trend in general at the station, but this increasing trend was not significant. There have been few normal years of runoff and many wet years at the station since the year 2000, and there were dramatic changes between the wet years and dry years. The change trend of the time series of the non-uniformity coefficient of the intra-annual runoff distribution at Lhasa Hydrological Station was not significant, and the inter-annual change of the proportion of the precipitation from July to September to the total precipitation over a whole year was not obvious.