中文摘要：

利用海拉尔河流域内气象站点1974—2006年冻土冻结深度资料和水文站点1974—2008年的径流资料,通过建立冻结深度和径流的关系,研究了区域近30年来冻土变化对径流变化的影响。结果表明：近30年来,海拉尔、坝后和红花尔基水文站1～3月份径流量有13%～20%的增长,牙克石水文站径流量增长不显著。退水曲线由陡峭趋于平滑,冬季2月份径流量与秋季11月份径流量比值呈增大趋势,同期流域冻土的最大冻结深度减小了50 cm左右。这表明海拉尔河流域冬季退水过程有减缓趋势且冻土的退化是导致退水变慢的主要原因。冻土退化的这一水文效应主要是由于：①随着冻土年内隔水效应减弱,流域内有更多的地表水入渗变成地下水,造成流域地下水储水量加大,导致冬季径流增加;②随着春夏季冻土平均厚度的减薄,流域地下水库库容增加,地下水枯季径流补给能力增强,导致流域退水时间延迟;③冻土对气候变暖的响应是一个缓慢的过程,因此冻土退化对径流过程的影响也是一个渐变过程。

英文摘要：

The effect of frost degradation on runoff variability in cold regions has become a hot issue under a changing climate.However,most existing researches on the subject have focused on exploring the relationship between permafrost degradation and runoff.In this study,the relationship between frost degradation and runoff and its variability over the last 30 years are investigated.The study uses the frozen depth data from the Manzhouli meteorological station for the period 1974—2006 and the monthly runoff data from four hydrological stations on the Hailaer River basin for the period 1974—2008.The result shows that the winter discharge has increased 13%-20% at the Hailaer,Bahou,and Honghuaerji three hydrologic stations,and no significant change is found at the fourth one（Yakeshi）.The discharge ratio of February to November（Q2/Q11） has increased significantly,while the maximum frozen depth at the Manzhouli meteorological station has decreased about 50cm for the same time period.These results imply that the winter recession curve has shown a slowing trend mainly due to the effect of frost degradation under climate warming.The hydrologic impact of frost degradation would be explainable by the following three aspects.First,the degradation of frozen ground will lead to the increases in aquifer thicknesses,surface water infiltration amounts,and groundwater storages.Subsequently,the groundwater increment will increase the winter discharge.Second,the circulation of groundwater is moving much more slowly than the surface water does.The enlarged groundwater reservoir will lead to a longer river runoff recession.Third,the response of frost degradation to climate warming is a slow process and its effect on runoff variability is also a gradual one.