Study On The Rule Of Evapotranspiration And Its Influencing Factors In Haihe River Basin

The Haihe River Basin is located in a semi-arid area and is one of the most important economic regions in my country,including Beijing,Tianjin and many other cities.Water resources are the main influencing factors for the development and evolution of the economic,social and ecological environment in the Haihe River Basin,and climate change will inevitably cause changes in the water cycle of the basin,changes in the total amount of water resources and spatial and temporal redistribution of water resources.This paper aims to study the law of evapotranspiration in the Haihe River Basin and its quantitative impact on meteorological factors.The research results are expected to provide watershed water resources allocation,water resources development and protection,comprehensive governance planning and the formulation of a sustainable development model of regional economy in the context of global change.Scientific basis.Based on the evapotranspiration data and meteorological data in the past 50 years in the Haihe River Basin,this paper first analyzes the relationship between evapotranspiration,potential evapotranspiration and actual evapotranspiration,and uses geographic weighted regression model to establish potential evapotranspiration and evaporation Spatial regression relationship of dish evaporation,and use Budyko hypothesis to establish a quantitative conversion relationship between actual evapotranspiration and potential evapotranspiration;and then introduce an econometric model with two-dimensional space-time-a panel data model to establish the evaporation dish evaporation Quantitative regression relations of meteorological factors such as average temperature,average wind speed,relative humidity,sunshine hours,and poor daily temperature,etc.,to study the quantification of evaporating dish evaporation in the Haihe River Basin by long-term climate change characterized by global warming and global darkening Impact;Taking actual evapotranspiration as the research object,the spatial quantitative regression relationship between it and relevant meteorological influencing factors is established by introducing a geographic regression model,with a view to distinguishing the difference between the actual evapotranspiration and the evaporation volume of the evaporating dish and the influencing factors.The study obtained the following results:(1)The least square method was used to analyze the measured meteorological data in the Haihe River Basin and surrounding stations.It was found that the evaporation volume of the evaporating dish in the Haihe River Basin decreased significantly at a rate of 22.89 mm/10 a and the temperature increased at a rate of 0.27 ?/10 a from 1960 to 2012.The trend shows that there is an overall "evaporation paradox" in the basin.Through ARCGIS,the data of evaporating dish evaporation,potential evaporation and actual evapotranspiration are visualized.The research results can provide a reference for the water resources planning of the basin.Taking the evaporating dish evaporation,potential evaporation and actual evapotranspiration in the Haihe River Basin as the research objects,the quantitative relationship between the evaporation amount of the evaporating dish and the potential evaporation is established through a geographically weighted regression model,and the potential evaporation is established through the Budyko assumption and the Fu Baopu formula The quantitative relationship between the amount and the actual evapotranspiration,the verification results show that the geographic weighted regression model and the Fu Baopu formula can be well applied to the calculation of evapotranspiration.The independent variable coefficient of geographic weighted regression results changed from a single value of global regression to a range of values,indicating that geographic weighted regression can better fit the actual situation.(2)The panel data model was used to conduct unit root test,Hausman test and F test on the meteorological factors such as the evaporation volume and wind speed and sunshine hours of the 1960-2012 evaporating dish in the Haihe River Basin.The variable coefficient fixed effect model was selected to model the meteorological data.The model regression results are good.From the perspective of single factor regression,the sunshine hours contribute the most to the evaporation of the evaporating dish,followed by relative humidity,poor daily temperature,wind speed,and average temperature;from full factor regression analysis It can be seen that the evaporation volume of the evaporating dish is negatively correlated with relative humidity,and positively correlated with sunshine hours,average temperature,daily temperature difference and wind speed;from the effect of fitting the average temperature and daily temperature difference respectively,the average temperature It is more suitable for the model fitting;comparing the regression results of average temperature and sunshine hours,the contribution of global darkening to the evaporation of the evaporating dish is greater than that of global warming.(3)Taking meteorological elements such as actual evapotranspiration and relative humidity in the Haihe River Basin as research objects,introducing a geographically weighted regression model,the actual evapotranspiration and wind speed,average temperature,relative humidity,and sunshine hours in the Haihe River Basin from 1984 to 2009 were analyzed The regression relationship between rainfall and rainfall has profoundly revealed the impact of these five meteorological factors on the actual evapotranspiration in the Haihe River Basin.Geographically weighted regression model was used to carry out regression analysis on actual evapotranspiration,rainfall and meteorological elements.Whether it is by different meteorological factors or chronological regression,the results show that the geographic weighted regression results are better than the global regression,indicating that the geographic weighted regression model can be better It is suitable for studying the analysis of changes in evapotranspiration;from single factor regression analysis,the sunshine hours in the Haihe River Basin during 1984-2009 contributed the most to the changes in actual evapotranspiration,followed by relative humidity,average temperature,rainfall,and wind speed.From the perspective of all factors,the actual evapotranspiration fits best with rainfall and meteorological factors in the 1990 s and the worst in the 1980 s.The coefficients of independent variables decrease gradually over the years,and their spatial distribution and positive and negative correlations show certain fluctuations in the chronology;from the wind speed,average temperature,relative humidity,sunshine hours and other meteorological factors and the actual evapotranspiration,direct regression results and potential Compared with the regression results of evapotranspiration and actual evapotranspiration,the regression effect of meteorological factors is better than the regression of potential evapotranspiration,which shows that the fitting effect of meteorological factors on actual evapotranspiration is better than potential evapotranspiration through this model;from rainfall According to the regression results of the volume and actual evapotranspiration and the regression results of potential evapotranspiration and actual evapotranspiration,the fitting effect of rainfall on the actual evapotranspiration is better than that of potential evapotranspiration,indicating that between 1984-2009,the Haihe River Basin's The actual evapotranspiration is mainly controlled by water supply conditions and is also affected by meteorological factors.