Study On Evaluation Method Of Irrigation Water Use Coefficient In Irrigation District

Water conservancy is the lifeblood of agriculture, agriculture is related to people’slivelihood problems. In recent years China has carried out a series of rehabilitation andwater-saving reform in large and medium-sized irrigated district and plant to found thehigh standard farmland for demonstration,aims to improve the efficiency and benefit ofthe irrigation water in irrigation district. Large irrigation district in Hebei province is animportant production base of food farmland in north of China, Irrigation agricultureplays an important rolein the economic development in Hebei province. The paperbasedon the large scale irrigation of Yehe district in Hebei as a representative for research andanalysis，based on the research and data analysis of irrigation water use coefficient inYehe district, make the measure result of canal system water lossand irrigation wateruse coefficient more accurate in Yehe district, theresearch on Yehe districtwill be has apositive guide to build a typical high standard demonstration farmland and furtherimprove the irrigation water-saving engineering technical measures and managementmeasures in large and medium-sized irrigation district in Hebei province.By collecting therelevant information both at home and abroadabout irrigation water usecoefficient, seeking the adaptive method of measuring the water use coefficient, waterenvironment and water quality of underground water in Yehe district. The projectselects four and fivebranch canal ofDatongcanal as typical systems forstudying onirrigation water use coefficient, and the main research results are as follows:(1)Study onirrigation water use coefficient of determination and calculationmethods.This paper analyzed the different determination method and calculationmethod of irrigation water use coefficient, including the head-tailmethod, the differenttesting methods of canal water use coefficient and the different methods of the fieldwater utilization coefficient. For different irrigation area, it needs to take adaptivemethod of irrigation water use coefficientbecause the different irrigation canals system,management system and thelabor and financial resources.Adopt the combination of thehead-tailmethod withthe measuring method of dynamic water(including the method ofhydraulic structures and current meter) to measure the irrigation water use coefficient inYehe district.(2)The determination result of irrigation water use coefficient in Yehe irrigationarea.The observation of typical systems of canal water use coefficient by parshall flume,trapezoidal measuring weir and current meter for supplemented, the calculation of fieldwater use coefficient is based on the field irrigation before and after the determination of soil moisture content and the field plot of inlet water. The result shows that irrigationwater use coefficient of typical systems by dynamic water method is0.403;Theresultabout irrigation water use coefficient by the head-tailmethodof Yehe district is0.409.(3)Study on the relationship between the field water effective use and the nitratenitrogen migration. Track the movement of nitrogenbefore and afterirrigationin the soilprofile every time, at the same time observe the level and quality of the undergroundwater, the density of soil, precipitation and evaporation.Disposal a large experimentaldata, the analysis result is that if the greater the net irrigation water of filed, the smallerthe water effective utilization coefficient of field,that the more obvious the movement ofnitrogen in the vertical direction of soil profile, the higher the level of ground water, themore the content of nitrogen in the groundwater.(4)The estimation of irrigation water use coefficient of large irrigation area in Hebeiprovince.Analysis and screening of large irrigation area in Hebei province, combinedwith the data of irrigation water use coefficient in selected typical large irrigation area,the prediction shows that irrigation water use coefficient of large irrigation area ofHebei province by s of0.533.(5)The measures of improving irrigation water use coefficient and groundwaterenvironmental.By analyzing the influence factors of irrigation water use coefficient andthe groundwater environment,it is more effective to increase the rate of channellining,enhance the managementmaintenance of channel system and optimizemanagement system of the water distributing and many other methods for improvingthe irrigation water use coefficient in irrigation district；At the same time puts forwardsome measures to improve ecological water environment inirrigation district, such asthe rational use of chemical fertilizer, using the optimal irrigation system and improvingirrigation water use coefficient, etc.