Study On Evapotranspiration In Golmud Region Based On Modis

Evapotranspiration is both the important component of water balance and the important part of the evaluation of water resources in arid areas. It contains soil evaporation and plant transpiration. The traditional calculating method of evapotranspiration is based on observation point only fitting for calculation of smaller areas, so it's limitted for computing larger evapotranspiration. With the development of remote sensing technology, based on the impact of MODIS, it can get NDVI and other important parameters. And then from a single point of promotion to the surface, it can make the calculation of evapotranspiration more precise.It's drought and little rain with strong evapotranspiration in Golmud region, so the contradiction of water supply and demand has become increasingly conspicuous. According to the study on the calculation of evapotranspiration based on MODIS, this paper estimates the evapotranspiration on the surface of the earth in Golmud region and does reaches on ways and means of regional evapotranspiration in summary and analysis on the basis of previous results. It provide basises for reducing invalid water evaporation and realizeing rational allocation and utilization of water resources. We get the following results due to the research:(1) The consume of evapotranspiration is from ground water in Golmud region and evapotranspiration is the main way to excretion for groundwater in arid areas. Due to regional groundwater depth and the difference between vegetation and soil lithology, evapotranspiration showes significantly zonal distribution. It's near zero due to the depth of groundwater in piedmont gobi gravel area, while in details on the plain where vegetation transpiration and soil evaporation is strong and has oasis band, evapotranspiration is more stronger. In salt crust lake area where the depth of groundwater is lower and has little vegetation with mainly soil evaporation, the transpiration is large.(2)In drought Golmud region, vegetation distribution is controlled mainly by groundwater, also affected by unsaturated zone lithology, water content and salinity. It only contains a small number of drought-tolerant vegetation in piedmont gobi where has deep groundwater while it only contains a few salt-tolerant vegetation distribution in salt lake shell area where has low groundwater because evaporation is so strong caused by high salt content that it's not suitable for vegetation growth: (3)It extends the ground observations to the entire region by remote sensing, using the regional and spatial continuity of remote sensing, based on the study on evapotranspiration by MODIS. So we get the vegetation index and albedo and other parameters in Golmud region obtained by model Golmud, evapotranspiration and spatial distribution.Golmud area is a basin in northwest island where it has a certain representation of hydrogeological conditions and water features. So it provides a good example on the rational exploitation of groundwater resources in arid areas and improving the ecological environment protection, if we carry out study on regional evapotranspiration and calculating on evapotranspiration.