STUDY ON SPATIALAND TEMPORAL DISTRIBUTION OF SNOWMELT

本研究的研究区域为天山乌鲁木齐河流域和长江上游纳其河流域。在这项研究中，收集了气象和水文数据，并描述了这些流域的一般特征。研究结果表明，这些流域覆盖了高海拔地区，气候干冷，冰川发育，主要应用分布式水文模型，得到了高精度的流域径流模型。在分布式水文模型的构建中，利用了全球地理信息系统（地球仪）。模型的输入数据为降水量和温度，输出的流域径流量与实测流量进行比较。分布式水文模型将流域地形离散为正方形网格点，降水量输入为 ...更多信息 每一个点。在每个网格点上，将降水分为蒸发、直接径流和基流。然后，直接径流将通过由网格点处的高程数据生成的水流网络路由到流域出口。将基流通过一种水库模型统一转换为流域径流，在分布式模型中，降水资料根据温度分为雨和雪两种处理，降雪量的计算考虑了雨量计的捕获率和海拔的依赖性。如果地面有雪，则根据度日法进行融雪计算。在这些计算中，每个网格点的温度是通过数据拟合的温度递减率获得的。最后通过对降雪模型参数的选取对模型进行了验证，计算的流域流量与实测数据吻合较好，表明了模型的有效性。少

The study fields of this study are the Urumqi River Basin in the Tianshan mountains and the Naqi River Basin, the upstream reach of the Changjiang River, China. In this study, the meteorological and hydrological data are collected and the general features of these basins are described. The result, in short, is stated that these basins cover the high-altitude region and the climate is dry and cold with development of glaciers at the high altitude.For the major part of this study, the distributed hydrological model is applied to these basins to obtain the high-accuracy rainfall-to-runoff model of these basins. In constructing the distributed hydrological model, the worldwide geographic information(GLOBE) is utilized. Input data to the model are precipitation and temperature and the output data of the basin runoff is compared with the observed discharge there.The distributed hydrological model discretizes the basin topography to the square mesh points and the precipitation is inputted at … More each gid point. At each grid point, the precipitation is divided to the evaporation, direct runoff and the baseflow. The direct runoff, then, is routed through the flow network generated from the elevation data at the grid points to the basin outlet. Wile the baseflow is collectively converted to the basin runoff through a kind of the reservoir model.In applying this distributed model, the precipitation data is treated either as rain or snow depending temperature and the amount of snowfall is calculated taking into account the catch ratio of the rain gage and the altitudinal dependence. If the snow is on the ground, the snowmelt calculation is conducted based of the degree-day method. In these calculations, temperature at each grid point is obtained with the data-fitted temperature lapse rate. The final verification of the model is conducted by selecting the parameters pertaining to the snowfall model, the calculated basin discharge reproduces the observed data satisfactorily, showing the validity of this model. Less