The Application Research On Distributed Snowmelt Runoff Model Based On GIS And RS In Arid Area--Take Urumqi River As The Example

In some high-altitude mountainous area of the western China, snowmelt water is the most important water resources and plays an important role in reasonable use of the water resources. To the reservoirs and the water power stations, snowmelt water is the primary storing source and take an important part in controlling the quantity of the water in reservoirs and reasonably arranging the water used in industry, agriculture and living. The oasis in the northern slope of Tianshan Mountain is the most important economic exploitation region in Xinjiang Province and its water source comes principally from the runoff in mountainous area of the northern slope of Tianshan Mountain. Spring is the low water season. Snowmelt water is the important water source that can release the drought, but there will be flood if the snowmelt water cause spring flood. So doing research on the rule of the snowmelt generation in the northern slope of Tianshan Mountain has great meaning for developing,using,and managing water resources in this area.This thesis takes the Urumqi River as experimental basin, making deep researches and analyses on application of the distributed model of snowmelt runoff in arid area, introducing the internal and external research actuality of remote sensing mapping for snow pack, introducing research actuality and developing trend of the distributed hydrological model, comparing several external common hydrological model about snowmelt runoff. This paper's aim is to construct a distributed model of snowmelt runoff suitable for arid area and it can be used to research and simulate other basins in arid area.The replenishment way of the Urumiqi River is the mixed replenishment of ice and snowmelt and rainwater. The inner drainage area has high-difference and unwell-balanced distributing types of runoff generation. Besides relating to altitude, it relates to ice and snow cover. These characters require adopting distributed hydrological model which can introduces different computing ways, different parameters and different input variables according to different situations when simulate the hydrological process. The distributed hydrological model based on DEM (digital elevation model) is also an available approach to resolve diversified hydrological estimation in the regions that are short of data.This thesis adopts a part of PRMS (Precipitation-Runoff Modelling System) about computing daily runoff of snowmelt and accords to the contour and the distributing situations of the vegetation in the basin to divide the whole drainage area into eighteen HRU (hydrological response unit) ,in every contour zone there is a weather station and we can use practical data from weather station as the input data for whole belt. According to the elevation of HRU and different months, this research adjusts the temperature and precipitation of HRU in which the daily temperature of HRU is adjusted by different lapse of temperature. The covering areas of snow in every HRU are calculated by MODIS image of the snow accumulation and melt. Combining the extracted snow area and DEM of basin, this research computes the runoff from quantity of snowmelt. Finally we calculate the flux from every HRU according to Muskingan rule, until to the basin export. Comparing the practical daily stream curve, this research finds that the trend of the simulated process curve inosculates the practical data and the part of low value is well meanwhile high value is smaller. The paper analyses and evaluates the error and proves this research has some utility direction meaning to water resources predictability and management in arid area. And divide the basin into HRU according to the contour and vegetation is one innovation of this thesis. This thesis use Rivertools to process DEM of Urumqi river basin. Rivertools is a kind of applied GIS software, which can analyze and display digital terrain, basin and river network. Its projecting function is that it can extract and analyze the hydrological character according to the very big DEM, so it is more rapid...