| Surface energy fluxes are not only very essential part for both global energy balance and water balance, but also an important impact on global climate change research; Water is all of this, to ensure the survival of mankind, maintain the sustainable development of society, economy and environment. Evapotranspiration is an important part of the water cycle and energy cycle. Traditional means of monitoring confined to observation of discrete points, and play a very important role and because the situation of underlying surface is complex, make evapotranspiration has a strong spatial and temporal heterogeneity, Therefore, during the research of evapotranspiration, single-point observations are not representative. The use of remote sensing to realize the possibility of point convert to the surface, which greatly promoted the study of regional evapotranspiration.In recent years, affected by global climate change and human activities, Water cycle and ecological patterns in arid zones basin has undergone profound changes, Jinghe River Basin, as a sub-basin of Aibi Lake watershed, have environmental characteristics typical of arid zone, ecosystem is extremely fragile, Therefore, this paper using MODIS data with meteorological observation data obtained by calculating surface energy fluxes these needed by improved SEBAL model, estimating the average instantaneous evapotranspiration of Jinghe River Basin by energy balance equation, and then analyze spatial and temporal variations in the watershed evapotranspiration.The main results are as follows:1.Using MODIS image inversed three important surface parameters of SEBAL model:surface albedo, normalized difference vegetation index and surface temperature. Using MODIS image divided LUCC and Analysis the temporal and spatial distribution of each parameter. Then calculate the surface net radiation, soil heat flux and latent heat flux, and analyze the spatial and temporal distribution characteristic. Overall, the spatial distribution s vertical zones of the individual flux are obvious; On the time scale, the degree of change in the overall basin is larger, and maximum value appeared in July, minimum value appeared in May.2.IN Jinghe River Basin, momentary evapotranspiration s vertical zonal pattern is quite obvious, Upstream is the highest value of evapotranspiration, Middle and lower reaches evapotranspiration is the lowest value, Comprehensive view from May to August, Showing a wavy decreasing mode:Basically, evapotranspiration of ice area less than Natural vegetation, Natural vegetation more than desert area, desert area less than artificial vegetation. The same time, momentary evapotranspiration of Jinghe River Basin area’s zonal pattern is quite obvious:each month momentary evapotranspiration of vegetation coverage area significantly larger than the desert area’s, artificial vegetation area of middle and lower reaches is less than natural vegetation of Upstream, but significantly higher than the non-vegetation coverage area.3.Selected NDVI, surface temperature and surface albedo and analyze the relationship between various parameters and the average monthly momentary evapotranspiration. The results showed that:in Jinghe River Basin, evapotranspiration has positive correlation with Normalized Difference Vegetation Index; evapotranspiration has positive negative with surface temperature and surface albedo, Proved in Jinghe River basin, water have a decisive impact on the earth’s surface evapotranspiration... |
PDF Full Text Request