Calculation And Analysis Of Effective Utilization Coefficient Of Irrigation Water In Farmland

In order to calculate the effective utilization coefficient of farmland irrigation water in recent years in Xianyang City and provide theoretical and technical support for the planning and utilization of regional water resources and the development of efficient water saving,this paper calculates the effective utilization coefficient of farmland irrigation water in Xianyang City from 2015 to 2017 by the first and last measurement algorithm,and uses the sectional first and last method to review the calculation results,and analyses the influencing factors of the effective utilization coefficient of farmland irrigation water.The following conclusions are drawn:(1)47 sample irrigation districts were selected in Xianyang City,including 3 large-scale irrigation districts,11 medium-sized irrigation districts,8 small-scale irrigation districts and 25 pure well irrigation districts.After calculation,the effective utilization coefficients of comprehensive farmland irrigation water in Xianyang City in 2015,2016 and 2017 are 0.5768,0.5770 and 0.5784,respectively.Compared with 2016 and 2015,2017 increased by 0.24% and 0.27% respectively.The results show that after a series of water-saving measures have been implemented in Xianyang City for three years,the effective utilization coefficient of farmland irrigation water shows an overall upward trend year by year.(2)The relationship between the effective utilization coefficients of farmland irrigation water in different types of irrigation areas in Xianyang City is as follows: large-scale irrigation area < medium-sized irrigation area < small-scale irrigation area < pure well irrigation area,and water-raising irrigation area > self-drainage irrigation area.The effective utilization coefficient of farmland irrigation water calculated by the piecewise head-tail method is higher than that calculated by the head-tail method.The results calculated by the two methods are quite different in large irrigation area and medium irrigation area,and the results calculated by the two methods in small irrigation area are slightly different.(3)The influencing factors of the effective utilization coefficient of farmland irrigation water are as follows: the length of seepage-proof canal,the lining rate of canal,the area of water-saving irrigation project,the scale of irrigation area,the management level of irrigation area,irrigation system,soil moisture and rainfall,while the effective utilization coefficient of farmland irrigation water is affected by crop irrigation system,the length of seepage-proof canal,the lining rate of canal and the area of water-saving irrigation project.The relationship between the effective utilization coefficient of farmland irrigation water in different soils is loam > clayey soil > sandy soil,and there is a positive correlation between the effective utilization coefficient of farmland irrigation water and rainfall.Within a certain range,the greater the rainfall,the greater the effective utilization coefficient of farmland irrigation water.Through calculation,the effective utilization coefficient of field irrigation water under inadequate irrigation system is 0.941,which is significantly higher than the effective utilization coefficient of field irrigation water in Jinghuiqu irrigation area as a whole 4.19%,and also significantly higher than that of field irrigation water under pure well irrigation area in Xianyang City 1.94%.It can be seen that inadequate irrigation system not only saves water,but also achieves water saving and high yield.It is also helpful to improve the effective utilization coefficient of farmland irrigation water.