SRM融雪径流模型在乌鲁木齐河源区的应用研究

Snowmelt runoff model applied in the headwaters region of Urumqi River

乌鲁木齐河源区发育现代冰川7条,冰川面积5.6 km2,并有大范围的积雪,冰雪消融期融雪径流对乌鲁木齐河贡献显著。应用SRM(snowmelt runoff model)融雪径流模型来探讨乌鲁木齐河源区融雪期径流情况,利用度日方法,由流域本身特征及参变量获取方法的深入分析来率定模型参数,应用模拟指标Nash-Sutcliffe系数R2=0.702和积差Dv=6.81%来评价模型表现,研究发现:(1)气温、降水作为该模型的直接驱动变量对模型的模拟较为敏感。尝试对乌乌鲁木齐河源区的气温、降水数据进行IDW插值并进行修正,使得模型模拟精度提高,对模型变量的输入精度问题上提供了新的思路;(2)不同高度带上积雪的度日因子并不是稳定的,而度日因子的选取与调整对模型也非常重要;(3)模型本身的局限性也导致模拟精度的降低。结果表明SRM模型可在乌鲁木齐河流域推广应用,这必将对认识和利用乌鲁木齐河流域冰雪水资源具有重要意义。

There are seven glaciers and large-scale snow above the Zongkong hydrological station of Urumqi River,and the snowmelt runoff in Urumqi River contribute significantly in the glacier ice and snow melting period.It is therefore essential to simulate the snow-melt runoff of Urumqi River,and also meaningful for the utilization of the snow water resources in the whole basin or even in Xinjiang province.In this paper,the SRM was applied to simulate snowmelt runoff in the headwaters region of Urumqi River.It is currently based on a simple degree day method.The daily precipitation,air temperature and snow cover area are the input data.In addition to the input variables,a number of basin characteristics such as basin area,zone area and the area elevation curve are also needed.The Digital Elevation Model are used to divide different zones of the basin,and MOD10A2 data are used for the accumulation of snow.Besides,the meteorological and hydrology data observed from May to August in 2008 are also used for this model.The region is divided to three zones and we get the curves of snow coverage shrinking derived from the MOD10A2 snow products,and the recession coefficients are also calculated in detail.According to the simulation,a final simulation scheme is selected as the final decision.The simulation fit indexes of Nash-Sutcliffe coefficient（R2）is 0.702 and the volume difference（Dv）is 6.81% which are fitted to the accuracy of snow melt model,and it also indicates that the SRM model can be applied in the whole Urumqi River.In addition,this application suggests that Urumqi River will be necessary for snow-melt runoff to meet with the needs of irrigation supply and water supply.This is particularly important for utilization of Urumqi River water resources.Meanwhile,the research also shows that ：（1）This study concludes that the snowmelt runoff model based on a degree day factor can efficiently simulate the daily discharge in the snow and glacier-fed catchments of the headwaters region of Urumqi River.Parameters which are sensitive to the results are degree day factor,recession coefficient K,the critical temperature value.（2）Air temperature and precipitation as the direct drive variables are more sensitive to the model.As the temperature and precipitation are not strictly comply with the temperature and precipitation gradient in headwaters region of Urumqi River,the IDW interpolation was used to solve this problem,thus,it provides a new train thought for the precision of the SRM model.（3）The degree day factor is not stable in different height belt while the degree day factor selection and adjustment is also very important to the simulation.While the snow density is closely related to the degree day factor,actual measurement snow density data are needed to measure in all the height belt.（4）SRM don’t take the infiltration,interception and evapotranspiration into account,so the simulation runoff is less than the measured runoff.Meantime,the study area in this paper is 28.9 km2;consider the resolution of MOD10A2 is 500 m× 500 m,there is a certain error in the curves of snow coverage shrinking.There are some shortcomings in this research;we intend to do better in the future research.