基于遥感(RS)和地理信息系统(GIS)技术,设计和构建了一个分布式融雪径流模型,整个分布式融雪径流过程的模拟计算基于能量平衡和水量平衡,由分布式栅格融雪过程、分布式栅格产流过程以及分布式栅格汇流过程组成,融雪以及产汇流过程全部基于栅格尺度,全面实现了融雪过程的分布式模拟.分布式栅格融雪过程中对"度日法"加以改进,引入了"单元时段"的概念,从而得到了"度分融雪模型";针对融雪过程中颇为复杂的冻融反复性难题,提出了旨在解释积雪冻融反复性物理机制的"冻融系数"的重要概念,对于准确把握融雪过程的物理机制具有重要意义.同时基于GIS开发了分布式融雪径流模拟系统,为分布式融雪径流模型的运行提供了平台和技术支持,二者均为融雪洪水预警决策支持系统的核心模块部分.基于由MODlS等遥感数据得到的积雪信息、地表温度等下垫面信息,基础地理信息数据如DEM及其空间分析数据和大量野外同步观测数据(积雪信息、气象数据),对典型研究区新疆军塘湖流域2006年春季典型融雪期(2006-03-06,11:00-2006-03-10,11:00)内的洪水过程进行了模拟,模拟结果精度较高,平均精度0.82,达到了融雪洪水预警预报的业务需求标准.

Snowmelt runoff is themain composition ofwater resources inmiddle and high latitude region. Research on the snowmelt runoff process are mi portant in monitoring and foresting flood and drought disaster as well as managing water resources. In recent years the studies on distributed snowmelt runoff model are based on the application and local mi provementof foreign mature models such as the SRM, have more lmi itations in their applicabilities. A Distributed SnowmeltRunoffModelbased on RS and GIS has been designed and explored in this paper. Themodel consists of three parts, grid snowmeltmode,l grid snowmelt flow generationmodel and grid snowmelt flow concentrationmode.l Itwasbased on energy balance andwaterquantitybalance. The grid snowmeltmodelwasbased on the energybalance. And the grid flow modelwas based on thewater volume balance aswell as the distributed grid runoffmode,l thus has formed a completely,distributed snowmelt runoffmodelwhich could apply to the actual service. Snowmelt and runoff processwere all based on grid scale, allofthe input/outputdatawere distributed processed, the prmi ary formatwereTIFF, so themodelwasprovided with distributing character and had strict physicalmechanism. An mi portant concept of“Unit Period ofTmi e”was put forward in the paper, and thereby developed a“Degree and CentSnowmeltRunoffModel”from the traditional“Degree-Day Method”which haswidespread application nowadays, for itwas not fit for the practical applications because of its glancing tmi e-resolution, in the snowmelt period, the processes were usually very unabiding, so the tmi e-step in day is not appropriate, butwith the“Degree and Cent SnowmeltRunoffModel”, the computing tmi e-stride of the snowmelt flood precaution decision support system could adjust itsel,f and tomake use in the real-tmi e computation and the forecast. Italso brought forward another mi portant concept of“Freezing andMelting Coefficient”, which was ami ed to explain the snow freezing andmelting repetitive physicalmechanism and this concept is significant to exactly hold the snowmelt process,because thewatermelting of snow/ice usually refreeze in the afternoon. Besides, aDistributed SnowmeltRunoffStmi ulating System byGIS has been developed, which is the platform and support of the running of the Distributed SnowmeltRunoff Model, has allofthe basic functionsofGIS, such as spatialanalysis, hydrologicalanalysis, dynamic smi ulation, and so on.Both themodel and the system are the kernelmodules of SnowmeltFlood Prewarning Decision Support System. At last,based on a greatdealofremote sensingdata, obtained distributed inputdata for themode,l forexample, distilled snow cover informationwithUnmixing PixelMethod, and land surface temperature (LST) with Split-window Arithmetic designed by ZhihaoQin, KebiaoMao and so on, with ourproper correction. Basic geo information data likeDEM and its relevantdata such as shope and asect, field smi ultaneous observation data mainly including weather data and hydrology data, were disposedwith uniform spatial resolution (30m×30m in thispaper) and the same data format(TIFF), stmi ulated the runoff process in representative snowmeltperiod in 2006 ofthe typicalstudy area, Juntanghu riverbasin, a closewatershed, which located in themiddle ofthe northernTianshanMountain,Xinjiang, China, the area of it is833·57km2, with theDistributed Snowmelt Runoff Stmi ulating System, the tmi e-step was 15 minutes. An average relative error of this model with the synchronous truemeasuring data was under 0·18, indicating that themodelwas able tomeet the need of snowmelt flood alarming and foresting.