塔里木河源区托什干河流域积雪动态及融雪径流模拟与预估

利用已被广泛使用的MODIS积雪数据, 获得了塔里木河源区之一的托什干河流域积雪变化信息. 结果表明: 流域积雪覆盖率时空差异显著, 在积雪丰富的年份, 1月积雪覆盖率可达90%以上, 但在积雪少的年份, 则只有50%; 2000年以来流域积雪呈现微弱增加的趋势, 积雪变化趋势呈现明显的时空差异. 相对于其他季节, 流域冬季积雪增加更为明显; 与其他高度带相比, 作为主要积雪覆盖区的海拔3 000~4 000 m高度带积雪的增加趋势也更为明显. 以流域所在的气象格网数据和积雪覆盖率变化曲线作为输入数据, 应用融雪径流模型(SRM)模拟了流域春季融雪径流过程, 率定了模型主要参数, 获得了较好的结果. 以CMIP5的3种RCP情景为驱动数据, 应用模型预估了流域2021-2050年的融雪径流状况, 结果显示 4月之前径流变化不明显, 之后径流峰值增大显著, 不同气候情景对径流的影响不明显.

Snow cover dynamics and snowmelt runoff modeling in the Toxkan River basin,source region of the Tarim River,Xinjiang

Snow is the most fast changing element in the cryosphere. A major proportion of flow in the Toxkan River is contributed by snowmelt runoff. The MODIS MOD10A2 remote sensing database of snow cover products from March 2000 to December 2012 was used to analyze the snow cover changes in the Toxkan River basin, one of the source regions of the Tarim River. It is shown that MODIS snow cover data is suitable of detection of spatial-temporal changes of snow cover across the basin and snow cover fraction has significant difference in temporal and spatial scale in the basin. In year with abundance of snow, snow cover fraction can reach more than 90% in January; but in less snow year, only 50%. Results show large variation in snow cover between 2000 and 2012 while an increasing trend is observed. Compared with other seasons, the increasing trend of snow cover is more obvious in winter. And compared with other elevation band, the increasing trend of snow cover over 3 000-4 000 m elevation band, which is the main snow cover distribution area, is more obvious. The Snowmelt Runoff Model (SRM) is used and forced with gridded temperature, precipitation and remotely sensed snow cover. The model is calibrated using monthly discharges from 2000 to 2004 and validated using monthly discharges from 2004 to 2006. It is shown that SRM can be used to simulate the stream flow in this basin with a certain degree of accuracy. There are no obvious differences for spring runoff simulation by using three RCP scenarios. In the future, spring runoff will increase significantly since April.