SRM融雪径流模型在长江源区冬克玛底河流域的应用

The Simulation of Snowmelt Runoff Model in the Dongkemadi River Basin, Headwater of the Yangtze River

冬克玛底河流域作为青藏高原腹地长江源区典型代表性高寒山区流域,有较大面积的冰川、积雪存在。本文以冬克玛底河流域2005年5￣10月的实测水文、气象资料为基础,运用SRM融雪径流模型对不同分带数对融雪径流模拟效果的影响和不同测站气温分别作为气温驱动变量对融雪径流模拟效果的影响分别进行了模拟试验。结果表明:不同分带会对SRM模型融雪径流量模拟产生一定的影响;而不同的气温作为驱动变量对模拟的效果影响很大,这表明SRM模型对气温驱动变量非常敏感。同样根据流域内径流与气温降水的相关分析看到日径流量与气温相关性较好,线性相关系数最好达到0.72,而径流与降水线性相关系数为0.20。根据以上模拟实验和相关分析选择合适的分带和具有代表性的站点气温,SRM模型模拟的两个优度指标最好可达到Nash-Sutcliffe系数(R2)=0.83和体积差(Dv)=0.95%。考虑到SRM模型对气温的敏感性,利用最终选择的模拟方案并结合气温升高1oC气候情景假设来考虑气温、降水和径流之间的关系。模拟结果表明:气温升高1oC后,(1)模拟时期内的径流总量由原来模拟的25.5×106m3增加到33×106m3;(2)冰川物质平衡线从原来的5600上升到5750米,冰川消融区从5.8km2增大到13.5km2,冰川消融量增加,对径流量的贡献明显增大。(3)气温的升高加速积雪融化并改变降水形态是径流在5￣6月变大的主导因素。7￣10月份的径流变大则主要是由于冰川消融。

As the representation of the typical river basin of headwater of the Yangtze River, Tibetan Plateau, Dongkemadi River Basin has glacier and snow accumulation. This paper uses the Snowmelt Runoff Model to simulate effects of different divisions of Dongkemadi River Basin to the hydrological process and simulate temperature at different stations as the driving factor to the effects of hydrological simulation, based on the hydrological data and meteorological data observed from May to October in 2005. According to the simulations, a final simulation scheme is selected as the final decision. The simulation result of different divisions of Dongkemadi River Basin shows its effect to the simulation. Simulation using different temperatures as driving factor shows that the SRM model is very sensitive to the effects of different temperatures. The correlation analysis shows that the correlation between runoff and air temperature is relatively good with best linear correlation coefficient reaching 0.72, but it can only reach 0.20 between runoff and precipitation. Based on the simulation and correlation analysis, the appropriate division and representative air temperature are selected to simulate the Dongkemadi River Basin＇s hydrological process. The coefficient of Nash Sutcliffe （R^2） is 0.83 and the volume difference of streamflow is 0.95%. Considering the sensitivity of the SRM model to air temperature, we simulated the relationship among air temperature, precipitation and runoff when the temperature rises by 1℃. The simulation result shows that： （1） The total amount of streamflow in the simulation period changed from 25.5 ×10^6m^3 to 33×10^6m^3 ; （2） The glacial mass balance line ascended from 5600 m to 5750 m and the area of ablation in Dongkemadi enlarged from 5.8 km^2 to 13.5 km^2, so that the contribution of the streamflow from glacial ablation is much greater; （3） because of the rise of air temperature, the speedup of snowmelt and the change of precipitation state are the main reasons of the runoff increase from May to June. The rise of runoff from July to October is mainly caused by the melting of glacier.