| Water resources is the most lack of region in northwest of china, water problem has caused a series of ecological and environmental problems. How to make the limited water resources to maximize the economic and environmental benefits, To this, relevant scholars did a lot of research work,and made a very impressive achievement,however,it is still not optimistic of the present situation of the ecological environment. Ebinur lake is the largest salt water lake in xinjiang, because of the unreasonable development and utilization of water resources, which also could not escape the fate of the ecological environment deterioration. Therefore,the paper based on the sub basin of Ebinur lake basin which is Boertala river basin as the study area, relying on the mentor’s national natural science fund project(that is land surface processes and human activities adaptability of the lake basin in arid areas—taking an example of Ebinur lake) to investigate the Ebinur lake basin for two years,obtaining first-hand measured data to use automatic meteorological station and homemade evapotranspiration,using meteorological data of Wenquan station and Bole station、 Modis and Landsat8 image data and DEM data,by applying the SEBAL model to calculate evaporation of basin from April to October in 2013,combining the method of evaporation and LUCC data to estimate ecological water requirement of typical vegetations,the results show that:(1) Taking the Landsat8 image data of surface observation in July 2013 a example,using Envi4.8 software for supervised classification, surface types of basin can be divided into bare land, grassland, forest land, arable land, water and other, through the statistical analysis of various kind of area knowing that, the bare land > grassland > forestland > cultivated land > water > other, among them,area of the bare land is the biggest,accountting for 38% of the basin area, while that of the other(including salted earth, snow area, residents, etc.) is the smallest, accounttingfor 2% of the basin area.(2) The change of daily evaporation is seasonal from Aril to October in 2013 in basin, surface evaporation is the smallset in spring, taking that of April 7 a example,most of the earth’s surface evaporation under 0.5 mm in watershed; Surface evaporation is the largest in summer, taking that of July 12 a example, most parts of the surface evaporation is more than 2 mm.(3) The change of the daily evaporation has the rules of vertical zonal distribution and the feature points of the opposite sex. Daily evaporation of plain is greater than that of mountains; That of downstream is greater than that of upstream; That of Farmland area is greater than that of desert; That of water is greater than that of adjacent area.(4) It has high consistency that the change of daily evaporation of valley grassland, farmland, forest land and the vegetationes growth stage,among them,that of crops has a significant change,between April and June are the golden age of crops from sowing to seedling growth, during the change of daily evaporation is gentle,the value is between 0.062 mm and 0.226 mm;Stem leaf of crop begines to flourish and then blossom with growth,in order to maintain the normal growth of that this period,which the demand for water also begines to increase,therefore, increase of crop daily evaporation is relatively quickly from July to September,that achieves maximum on September 14,the value is 1.634 mm;Since then, crop physiology begines to decline with the harvest of the fruit crop, crop evapotranspiration quantity reduced to 1.094 mm on October 16,.(5) Daily ecological water requirement of typical vegetationes all show a trend of the first increase after decrease,especially it is the most significant of the change of grassland ecological water demand,the maximum value appeared on the July 12, that is 61808.02 m3, minimum value appeared on the April 7,it is 235.46 m3, extremum difference is 61572.56 m3; The change of that of forest land was relatively flat, maximum value appeared on the June 10, it is 4117.06 m3;The maximum value of farmland ecological water requirement appears ahead of grassland and woodland espectively for three monthes,two mouthes.(6) On the basis of the 2013 years, assuming that daily ecological water requirement of typical vegetationes is uniform within month, so grassland, cultivated land and forest land ecological water requirement were 0.054 x 108 m3, 0.023 x108 m3, 0.004 x 108 m3 for a growing season. It is the largest of the grassland ecological water requirement. |
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