青藏高原东部地区水文气候变化趋势分析

青藏高原是众多河流的发源地,为了解该地区水文气候变化的情况,对其东部地区雅鲁藏布江(奴下站)、怒江(嘉玉桥站)、澜沧江(昌都站)、通天河(直门达站)、雅砻江(泸宁站)、黄河(唐乃亥站)共6个流域自20世纪80年代以来的年气温、年降雨和年径流的变化趋势进行研究,分析了年径流对气候变化的响应。结果表明:6个流域的年气温和年降雨基本呈较明显的上升趋势;年径流受气温和降雨的共同影响,奴下站、嘉玉桥站和泸宁站呈一定的上升趋势,昌都站、直门达站和唐乃亥站呈一定的下降趋势。区域内径流多年平均变化率与冰雪面积比例大致呈正相关关系:年径流呈现上升趋势的流域,冰雪面积比例较大,受降雨增加和融雪增加的影响偏大;年径流呈下降趋势的流域,冰雪面积比例较小,受气温上升导致蒸散发增大使径流减少的影响偏大。这些研究结果将对青藏高原地区防洪抗旱、水资源的合理配置和开发、区域水资源可持续利用等具有重要的作用和意义。

Analysis on the Trends of Hydroclimatic Variation in Eastern Tibetan Plateau

The Tibetan Plateau is the source area of many major rivers in Asia. In order to realize the variation of hydrology and climate in the Tibetan Plateau, this paper investigated variation trends of annual temperature, annual precipitation and annual runoff since 1980s in six large river basins including the Yalung Zangbo River (Nuxia station), the Salween River (Jiayuqiao station), the Mekong River (Changdu station),the Tongtianhe River (Zhimenda station), the Yalongjiang River (Luning station) and the Yellow River ( Tangnaihai station) in Eastern Tibetan Plateau, and analyzed the response of runoff to the variation of climatic elements ( precipitation and temperature) . The results show that annual mean temperature and precipitation at all stations show obviously increasing trends, but the annual runoff affected by temperature and precipitation exhibits different trends:at Nuxia station, Jiayuqiao station and Luning sta-tion, the runoff shows slightly increasing trend, while shows decreasing trend at the other three stations. By analyzing the relationship between the trend of annual runoff and the area ratio of snow and ice, the change trend of annual runoff has a positive correlation with the area ratio of snow and ice:the area ratio of snow and ice is larger in the basins where the annual runoff has an upward trend, the change trend of runoff is greatly affected by the increase of precipitation and snowmelt, while the area ratio of snow and ice is smaller in the basins where the annual runoff has a downward trend, the impact of the runoff decreasing caused by the increase of evapotranspira-tion due to rising temperatures is large. These results will play an important role in flood control and drought relief, rational allocation of water resources and the sustainable utilization of regional water resources in the Tibetan Plateau.