Studying On Meteorology Index Of Water-Saving Irrigation Levels Of Major Crops And Risk Assessment

Water-saving irrigation indicators of the crops in different development periods are finded out in this paper by using national meteorological data of 560 stations from 1961 to 2008,the reduction probability of production,soil moisture and irrigation data, based on water balance principle, combining with crop production-water relations and crop water stress sensitivity index, analyzing the relationship of the rate of water deficit at different development state of four crops(winter wheat,summer maize,cotton and soybean), water deficit and the rate of production cut.Selecting the years in which the water offered is deficient and the production is less than the trends production, removing useless data, then a long era of water deficit sequences could be constructed.Based on these,the reduction rate of different levels of crop water deficit corresponding to the meteorological indicators of water-saving irrigation level of 4 crops are analyzed,Ⅰ~Ⅲgrades of the risk of water deficiency are eatimated,and the water-saving irrigation Weather Risk Maps of 4 crops(winter wheat, maize, cotton and soybean) under natural conditions are given,which would be useful.To optimize the irrigation system and provide theoretical support to improve water use efficiency.The conclusions are shown as follows:1) Based on crop yield-water function of FAO-1979, analyzing the relationship between the crop water deficiency and the cut rate, fitting function equations are established, which are used to measure costs and irrigation efficiency increasement, optimize the irrigation systems;2) The spatial distribution of the average years of climatic resources of four crops is revelaled: the serious area of water distribution losses of winter wheat is in North China, Southwest and Xinjiang; the water deficit of summer maize distribute along with Guangxi - Hunan - Hubei - Henan Province - Central China Hebei, water deficit is less than 40%; cotton in the north and the Xinjiang region in Huang; the average water deficit rate of the soybean in Northeast China is generally between 20 % to 60%;3)Verifying the meteorological indicators of water-saving irrigation levels of winter wheat, summer maize, cotton and bean in positive and negative direction,the details of meteorological water saving irrigation indexes are concluded: winter wheat: the whole growth period:[ 15,35), [35,50), and≥50; sowing– jointing period: [20,40), [40,60), and≥60; jointing - heading period: [15,30), [30,45), and≥45; heading– Mature period: [15,30), [30,50), and≥50. Summer maize: the whole growth period:[10,25), [25,45), and≥45; sowing– jointing period: [15,30), [30,45), and≥45; jointing– heading period: [15,25), [25,45), and≥45; heading– Mature period: [15,30), [30,40), and≥40. cotton: the whole growth period:[15,30), [30,50), and≥50; sowing– squaring period: [20,40), [40,60), and≥60; bud– blossom period: [20,35 ), [35,45), and≥45; flowering - boll opening period: [20,35), [35,50), and≥50. Soybean: the whole growth period: [15,35), [35,50), and≥50%; sowing– Branch period: [20,40), [40,60), and≥60; branches– pod period:: [20 , 30), [30,45), and≥45; pod– Mature period: [15,30), [30,45), and≥45.4) Based on distribution of the water deficit risk of the four crops in nature, the maps of risk and water deficit risk distribution at different water-saving irrigation meteorological levels are drawn. It's aimed to provide support to optimize the irrigation system and improve water use efficiency by quantifying the risk of irrigation.