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黑河上游处于高寒山区,开展冰冻圈水文过程对径流的影响研究,对于判断该地区径流变化趋势及其可持续性具有重要意义。本文应用基流分割、逐步多元回归等方法,分析了1960—2013年黑河上游出山径流量的变化及其原因,重点估计了融雪、冰川融化对径流的贡献,探讨了土壤冻融过程对径流变化的可能影响。分析结果表明,黑河上游山区河川径流在近54年间呈现上升趋势,其中以基流部分的上升为主。降水与气温变化对河川径流上升均有较大贡献。导致春季径流增加的主要因素为温度、降水次之;导致秋季径流增加的主要因素为降水、温度次之。夏季黑河上游东支的雨强有显著增大趋势(日雨量增幅为0.9 mm/10 a),对于河川径流贡献的比例约为15%。黑河山区的逐年降雪量变化不显著,冰川融化对径流增加的贡献小于10%。由此推断气温上升导致基流增加的主要原因是:气温升高导致高寒山区冻土活动层增厚,增加了土壤蓄水容量,从而导致降雨下渗量增加和基流量增大。由于黑河上游冻土分布广泛,未来气温持续上升的情况下,这种产流机制变化导致的基流增加具有可持续性。
The upper reaches of the Heihe River is in the alpine region. It is of great significance to study the impact of the hydrological process on the runoff in the cryosphere to determine the trend and sustainability of runoff in this region. Based on the method of base flow segmentation and stepwise multiple regression, the change of runoff from the upper reaches of the Heihe River from 1960 to 2013 and its causes were analyzed. The contribution of snowmelt and glacier melt to runoff was estimated. The effects of freeze-thaw cycles on runoff The possible impact. The results show that the runoff of rivers in the upper reaches of Heihe River has been on an upward trend in the recent 54 years, with the increase of base flow mainly. Precipitation and temperature changes have a greater contribution to the runoff of rivers. The main factors leading to the increase of spring runoff are temperature and precipitation; the main factors that lead to the increase of runoff in autumn are precipitation and temperature. The rainfall intensity of the east branch of the upper reaches of the Heihe River in summer increased significantly (the increase of daily rainfall was 0.9 mm / 10 a) and the contribution to the river runoff was about 15%. The annual snowfall in Heihe mountain area does not change significantly, and the contribution of glacial melt to runoff is less than 10%. It can be inferred that the main reason for the increase of base flow caused by rising air temperature is that the rising of temperature leads to the thickening of the active layer of permafrost in the alpine region and the increase of soil water storage capacity, resulting in the increase of rainfall infiltration and the increase of base flow. Due to the widespread distribution of permafrost in the upper reaches of the Heihe River and the rising temperatures in the future, the increase of base flow caused by this mechanism of production flow is sustainable.