基于能量守恒和3S技术的分布式冰川融水径流过程模拟

A Distributed Simulation Model on Runoff Process from Glacial Meltwater Based on Energy Conservation and 3S Technology

面向对象的分布式冰川融水径流模型的建立,不仅可以提高模拟计算的精度,而且可清楚地反映冰川融水径流各影响因子的特征,对研究中国西部地区流域水文循环具有重要意义。本研究借助3S技术,根据能量守恒和水量平衡原理,建立了包括栅格冰川融水、融水产流以及汇流子系统且具有严格物理意义的分布式冰川融水径流过程模型。通过DEM数字高程技术,提取流域地理信息;基于Landsat-7卫星遥感影像,反演获得流域的冰川覆盖信息和地表反射率信息。将获取的这些信息作为冰川融水径流过程模型的基本输入数据,分别对扎当冰川和七一冰川融水的日径流过程进行了模拟计算。结果显示,该模型对2个冰川径流量日变化过程的模拟结果与实测过程一致。2个冰川的日径流峰值与其实测值的差异小于6.0%,日径流过程的Nash-Sutcliffe效率系数均大于0.81。所建模型计算结果可靠,可以为实时预测冰川融水径流变化过程提供技术支撑。

To establish an object-oriented distributed glacier meltwater runoff model can not only improve the accuracy of simulation calculation,but also clearly reflect the influence characteristics of its each influencing factor,which is of great significance for the study of hydrological cycle in western China.Based on the principles of energy conservation and water balance,a distributed process model of glacier meltwater runoff,including grid glacier melting,runoff generation,and runoff confluence subsystems,with strict physical significance was established with the help of 3 S(Remote Sensing,Geography Information System,and Global Positioning System)technologies.The glacier melting subsystem was based on the energy conservation principle near ground surface,the runoff generation subsystem was on regional water mass balance,and the runoff confluence subsystem was based on variable isochronous line convergence method.By means of DEM(Digital Elevation Model)digital elevation technology,the geographic information of the studied watershed was extracted.The glacier coverage information and surface reflectance information of the watershed were obtained by inversion method based on Landsat-7 satellite remote sensing images.The acquired information was used as the basic input data of the established model of glacier meltwater runoff process,and the variation processes of daily runoff with time from the Zhadang Glacier and the Qiyi Glacier were simulated and calculated,respectively.The simulation results showed that the diurnal variation processes of glacier meltwater runoff with time calculated by the established model were consistent with their measured processes for the two studied glaciers.The diurnal change process of the meltwater runoff with time was closely related to air temperature,and the change process of the runoff lagged behind that of the temperature by about 2~4 h.The difference between the calculated daily runoff peak value and its measured value was smaller than 6.0%,and the Nash-Sutcliffe efficiency coefficient of daily runoff process was greater than 0.81 for both the glaciers.It can be concluded that the established distributed model of glacier meltwater runoff process is reliable,which provides a technical support for the real-time prediction of runoff process from glacial meltwater.Some necessary simplifications,such as the nature of ice and snow(new and old,pollution,surface cracking,etc.)and the local generalization treatment of near-surface heat exchange and transfer,were introduced in the development of mathematical sub-models in this study,and their more reasonable expressions require further in-depth study.