Comparing Different Methods of Calculating Crop Evapotranspiration & Study on Limited Irrigation Forecasting

Water shortages seriously restricting the sustainable development of agriculture . Minimize the adverse impact on our country there is a large area of ??arid and semi- arid areas , a practical guide to the implementation of the non - sufficient irrigation water for agricultural irrigation for the rational use of the region of the type , and allows the use of non - sufficient irrigation water shortages caused to crops . Take into account the different regions can take advantage of the meteorological data , the study selected five of the United Nations Food and Agriculture Organization (FAO) recommended ( FAO Penman - Monteith method , the radiation method , the Blaney - Christopher Bender method Penman a comparative study of modified method and Hargraves method ) to calculate the reference crop evapotranspiration and recognized FAO Penman - Monteith method as a standard , the other four methods of correction obtained Fuxin region corresponding correction formula . The study shows that the four methods , in addition to the the the Blaney - Kerry Del methods Penman - Monteith method for Fuxin region has exponential relationship Penman - Monteith method , the other three methods have a linear relationship . Four methods , radiation amended in line with the best calculations with the Penman - Monteith method , the average relative error of 3 % ; the Hargraves methods only need to calculate the periods of highest and lowest temperature and other meteorological data , it is the method has a high practical value ; formal methods , followed by Penman repair ; Blaney - Christopher Bender ( Blaney - Griddle ) method is the worst , even if after the correction , the average error of the method was 10 % . Fuxin region of reference crop evapotranspiration calculation methods of research results , and to achieve full irrigation forecast system three main functions : calculate the reference crop evapotranspiration , irrigation forecasting and a limited amount of water optimal allocation . The specific design of the system , using VB Integrated Development Environment is a function of the different components of the system . The system as a whole has a friendly interface , reasonable structure , simple operation .