Research Of Evapotranspiration Change And Effect Factors In The Yellow River Delta

Evapotranspiration is an important parameter in water cycle, and it affects the redistributionof precipitation and radiant energy on the surface. Accurate prediction of the evapotranspirationin a area take an important role in the rational use and distribution of water resources, andecological protection. It also provides a scientific basis for the in-depth understanding of thewater cycle conditions under different land types. Knowing the evaporation process andmechanism is important to understand a wide range of surface energy balance and water balance.It can help us to know the land surface process. It also can correctly evaluate the impact ofclimate change and human activities on the ecological environment. The remotesensing technology develops rapidly. It can be combined with the traditional subject, forming alarge number of very important interdisciplinary, which provides a new the solution formany applications and scientific problems.The Yellow River delta efficient and ecological economic zone is based on Yellow Rivehistorical impact plain，which is the geography of economic region surrounding extension. It hasthe excellent geographical location, rich natural resources and unique ecosystems. The YellowRiver delta efficient and ecological economic zone is short of water resources, with serioussalinization and deterioration of water quality.This paper selects a calculation model——SEBS Model， with a successfulapplication experience and high accuracy. This paper collects the MODIS Date in the YellowRiver delta efficient and ecological economic zone. Then according to the MODIS Date and thegeographical situation in the delta, calculate NDVI, surface emissivity, surface albedo, surfacetemperature and atmospheric transmittance parameters through the ENVI software. Then basedon the SEBS model, using the inverse calculation of the parameters and the local climate data,calculate the net radiation flux, soil heat flux and sensible heat flux surface fluxes. Atlast estimate the evapotranspiration of some months in the Yellow River delta efficient andecological economic zone in the year2002–2012.This paper analyzes the change ofevapotranspiration in the Yellow River delta from space and time scale. Finally, from the type ofland use, the normalized difference vegetation index and climate factors to analysis how toinfluence the evapotranspiration in Yellow River delta efficient and ecological economic zone.It shows that using SEBS model to calculate the evapotranspiration can get an accuracydate. It shows a decreasing trend from the seaside to inland. But in some individual area the evapotranspiration has a large or small number, which appears in the form of spotty. Within ayear with the passage of time it shows an increasing first and then decreasing trend with thepassage of time, which is the minimum in January and the maximum In July. In the same monthsof different years, the evapotranspiration don’t have big changes. But the areaevapotranspiration has an increasing trend year by year. Land use type can decide the levelof daily evapotranspiration. The evapotranspiration and NDVI has a good relevance. There ispositive correlation to changes in temperature and wind speed and evapotranspiration, andthe relative humidity and evapotranspiration has a negative correlation.