| The research on snowmelt and rainfall runoff and the application of flood forecasting is restricted in high cold alpine areas because of the complexity of precipitation distribution law, the variability of snowmelt factor, the lack of monitored data and so on. Considering the distributed hydrological model reflects some advantages in snowmelt runoff and flood-forecast research, so the distributed hydrological model is built in Tianshan Mountain areas based on the Xinanjiang Model using DEMs, GIS technology and snow monitoring data from remote sensing satellite data of study area. It will be fully used that measured data are from the basic station, from the meteorological station, from automatic system of hydrologic data collection and transmission, from remote sensing data and that experience gained by the engineering and skilled workers in the primary river management unit. The detection ability of TRMM/TMI satellite for precipitation in Tianshan Mountains is discussed based on TRMM/TMI satellite precipitation data and observed precipitation data, and the availability of TRMM/TMI satellite in precipitation analysis and forecast in where no precipitation monitoring as the limitation on natural and terrain condition is analyzed. By disassembling the outflow of watershed and selecting rationality analysis methods on delineation hydrological process, the laws on precipitation vertical distribution and space and time distribution of snowmelt factor in Tianshan Mountains are analyzed, and found the expression ways on before-mentioned laws and distribution. It is important that laws will provide the basis for parameter identification of hydrology forecast model in lack-data watershed, and advance the snowmelt runoff research means. At the same time, they provide the concrete forecast model and the method for Xinjiang floods prevents and early warning support system. The main results as follow:(1) The spatial distribution variability of precipitation is complex in the west of Tianshan Mountains, but it has obvious law. From horizontal distributions of precipitation we find that the precipitation is more in high mountainous areas than low mountainous areas, but there is more precipitation in windward slope of lower elevations zones than higher elevations zones. The horizontal distribution law of annual total precipitation is that there is a high value area where is located in windward slope based on the ridge line elevations from the top down, precipitation distribution law is correlative with vapor origins and aspect in middle-high mountain areas. From the vertical direction we know the rules are: 1) Precipitation variation rule is obviously different with elevation on the north and south slopes of the Tianshan Mountains, and it represents different vertical variation characters in different slope gradients of Tianshan Mountain areas. There is a high-value zone on precipitation in Yili river basin and the middle part of southern slope of Tianshan Mountains. The maximum belt of precipitation is about 3241m in Yili river basin and the middle part of southern slope of Tianshan Mountains is about 3558m. The precipitation showes a S-shaped autocatalytic characteristics with the elevation changing at elevations lower than 5000m in the west of northern slope of Tianshan Mountains, there are no obviously changing inflexions. The precipitation variation tendency is precipitation increasing with the change of elevaions, but the fluctuate is larger, and it showes two S-shaped autocatalytic characteristics.2) There are larger differences on the vertical change rate of precipitation. The vertical change rate of precipitation is -7.42～5.64mm/100m at elevations lower than 4500m in Yili river basin; the vertical change rate of precipitation is -13.39～37.78mm/100m at elevations lower than 4500m in the middle part of southern slope of Tianshan Mountains; the vertical change rate of precipitation is 1.14～8.95mm/100m at elevations lower than 5000m in the middle northern piedmont of Tianshan Mountains; the vertical change rate of precipitation is -9.98～17.80mm/100m in the west of northern slope of Tianshan Mountains.(2)The snow cover and NDVI have better correlation besides themselves variation laws. The snow cover rate represents decrease tendency between 2001 and 2008, and land cover commonly exists obvious ameliorating tendency, but the scope is small.(3) Through analyzing the long-term trend of hydrological and meteorological changes in study area showed that temperature presents an obvious increasing tendency, and the variable tendency of precipitation is not obvious. Contrast analysis the land-use types with resolution 1km between 1980's and 2000 showed that the land use types had been changed not much in mountainous area. The mainly changing is cultivated land to grassland and the proportion of residential and mining land. The proportion of residential and mining land increase quickly. Using the SWAT model we found the response on snowmelt runoff in the mountainous regions to LUCC was a close correspondence between 1980's and 2000, and the influence on LUCC to runoff basically had no large change.(4) The distributed hydrological model on the west Tianshan Mountains is built. In order to reduce the model development cost, the GIS open source project GDAL and MapWinGIS are used and the software has some functions such as the basic function of GIS, the module for watershed information extraction is developed, it could easily realize the watershed information extraction by DEM data. Based on three-water-source Xinanjiang Model, the digital hydrological model which considered snowmelt, ice and frozen soil hydrology process is built. The model is applied to simulate the snowmelt-runoff of Kashen river watershed in 2005 and the results are better and reflect the actual changing trend of the runoff.
|
PDF Full Text Request