Study Of Variation Characteristics Of Water Efficiency Of Irrigation In Different Years

Water efficiency of irrigation is an important reference index to evaluate and measure the efficiency of irrigation water use and the potential of water-saving.It is a comprehensive index reflecting the level of irrigation technology in irrigation areas,the quality of irrigation works,and the level of management of agricultural irrigation.With the impact of global meteorological changes,the occurrence frequency of droughts and floods(waterlogging)has intensified.Thus,studies on the impact of drought and waterlogging conditions on Water efficiency of irrigation can provide important guidance for the management of irrigation areas and the efficient use of water resources.This thesis takes the Wenxikou Irrigation District in Zhongxiang City,Hubei Province as the research object,and studies the temporal and spatial distribution characteristics and evolution trends of drought and flood in Hubei Province and Zhongxiang City based on meteorological data.Field experiments were conducted to investigate the effects of drought or flood conditions on root growth and water efficiency of application.Further,a software based on Kostiakov formula capable of computing water efficiency of canal system was developed using.Net.Using the software,the variation regularities of Water efficiency of canal system,water efficiency of application and water efficiency of irrigation in different conditions of drought and waterlogging were analyzed.The main results are as follows:(i)Hubei Province generally experiences frequent occurrences of drought and flood disasters,and the disasters occur alternately with an overall trend of aridity.Summer is the high frequency season of droughts and waterlogging in Hubei Province.The frequency of drought in spring and summer in Hubei Province shows an upward trend.The frequencies of drought in autumn,waterlogging in spring,autumn and winter show a downward trend.Summer has the most frequent occurrence of droughts and floods in Zhongxiang.Spring drought and autumn waterlogging also occur frequently in this area.(ii)Minirhizotron is a suitable method for observing the growth of roots dynamically.Drought and waterlogging stress conditions affect the depth of cotton roots.After the application of drought and waterlogging stress on cotton's boll-setting stage,the maximum root depth of control treatment was 55?60cm,the drought treatment was 60?65cm,and the waterlogging treatment was 45?55cm.(iii)Several types of empirical formula methods were compared and analyzed.A software for estimating the Water efficiency of canal system was developed based on the formula of Kostiakov.(?)The Water efficiency of irrigation of Wenxiakou irrigation region was calculated to be 0.4932 using the software,which is basically consistent with the measured data.As the year type changed from heavy waterlogging to heavy drought,the Water efficiency of application increased from 0.8600 to 0.9120,the Water efficiency of canal system increased from 0.5160 to 0.5840,and the Water efficiency of irrigation increased from 0.4437 to 0.5327.(?)Under normal years,the maximum water efficiency of irrigation after lining reconstruction of the channel is 0.8146,which can create an improvement potential of 0.3214.The maximum water efficiency of canal system after same treatment is 0.9194,which can create an improvement potential of 0.3567.Comparing the coefficient of correspondence between normal years and droughts or waterlogging years,the type of drought and waterlogging has no effect on the growth potential of Water efficiency of irrigation.A comparison of the impact on the increase of Water efficiency of canal system is as follows:waterlogging year>normal year>drought year.(?)The trunk canals and the branch canals should have a high priority when lining.The lining priority should be given to the trunk canal,branch canal and sublateral canal of the North canal system,branch canal and sublateral canal of the South canal system in this area.