天山托木尔型山谷冰川度日因子空间参数化方案实验研究

Abstract：In Northwest China, glacial melt represents a very significant source of streamflow, especially in arid and semi-arid inland river basins. Degree-day model has been widely applied in the estimation of meltwater, and the Degree-day factor is an important parameter in model, the model can not simulate well the change of ablation during the year when use a fixed value of Degree-day factor. And the research of study on the spatial sparameterization schemes of Degree-day Factors in a valley glacier of Tomur in Tianshan has not yet commenced. This item will rely on the observation system of Koxkar Glacier Basin Filed station, it draws up to observed the ablation of glacier and snow which consider the slope and the thinkness of debris-covered in different altitude. We will study on the spatial and temporal difference of degree-day factors and analysis the regular pattern of variation on the valley glacier based meteorological data in glacier area. And we analysis the relationship between Degree-day factor and the thickness of debris, temperature, sonw, the movement of glacier and terrain. Considering that, this item will improve parameterized scheme of distributed glacial ablation model and couple the degree-day mass-balance model with HBV model which considered the spatial change of Degree-day factors. On this basis, the extended HBV model will be applied to simulate the hydrological processes in the Koxkar Glacier Basin, and the result will also be cpmpared with observation data and simulated result of original model which consider the single-factor degree-day, then we discuss the estimation and composition of glacial runoff which was influenced by the spatial and temporal difference of degree-day factors in hydrological model. Finally, we intend to provide reference for spatial sparameterization schemes of Degree-day factors in the glacier hydrological model .

摘要：冰川融水是我国西北地区水资源重要来源。度日模型在冰川消融估算中应用较为广泛，度日因子是该模型的重要参数。对于冰面特性复杂的天山托木尔型山谷冰川，利用单一度日因子的度日模型不能较好模拟消融的年内变化过程。目前针对此类型冰川度日因子的参数化方案研究尚未展开。本项目拟依托天山托木尔峰南坡科其喀尔冰川观测站，在消融期利用花杆对冰川不同海拔高度、坡度坡向、表碛厚度区分别进行消融观测试验。结合气象观测数据，计算度日因子的时空分布特征，分析表碛厚度、地形、地表温度、冰川运动以及降雪对度日因子的影响机理，构建度日因子的空间参数化方案。在此基础上，完善传统度日模型中度日因子的参数化方案并耦合到HBV水文模型中进行试验；以观测的径流为基础，对比原来冰川消融估算方案和度日因子参数化的消融方案的模拟效果。探讨度日因子时空差异对冰川径流估算的影响，为托木尔型山谷冰川的消融估算中提供度日因子参数化方案参考依据。

本项目托木尔型冰川的不同海拔高度，按照不同坡度坡向、不同表碛厚度区建立消融观测，进行降水、蒸发观测，并利用花杆进行冰、雪消融观测试验。通过气象和物质平衡观测数据，分析托木尔大型山谷冰川度日因子的时间和空间差异及分布特征。利用不同海拔的气象观测数据，在原来单一度日因子模型基础上考虑度日因子时空变化，将其与HBV水文模型进行耦合；以观测的径流数据为基础，检验对比模型的原来冰川消融估算方案和改进的消融方案在冰川流域尺度的水文模拟效果，为大型山谷冰川水文模型中的度日因子空间参数化方案及提高提高模型精度提供参考依据。科其喀尔冰川度日因子介于3.05-13.03mm·℃- 1·d - 1之间,平均值为9.26mm·℃- 1·d-1。利用计算的度日因子，为HBV水文模型中重要的冰川消融估算提供参数，并且得出HBV模型在我国天山山区的冰川流域模拟年月径流深的效果明显好于日径流深。参数率定期的日径流深模拟Reff都在0.75以上，月径流深模拟效果达到0.92。通过模型来模拟年月尺度的径流深精度是可信的。利用研究区周边４个气象站1959-2009年的气温、降水数据，重建了科其喀尔大本营处近50a的气温、降水。通过插值发现：54a来，流域的温度和降水都呈增加趋势，温度平均递增0.31℃（10a）-1；降水平均递增4.6 mm.a-1。采用率定得到的模型参数组合，假设各个参数没有发生变化，模拟得到1959-2009年50a的年径流深和冰川物质平衡变化过程．结果表明：在最近的50a中研究区冰川物质平衡呈亏损状态，平均-370.4 mm.a-1；年径流深呈波动上升，平均增加5.51 mm.a-1。