Calculation Of Effective Utilization Coefficient Of Farmland Irrigation Water In Hetao Irrigation Area Based On Multi-source Remote Sensing

The effective utilization coefficient of farmland irrigation water is the basic data of quantitative evaluation of agricultural water resource utilization efficiency,which plays an important guiding role in the construction of high-standard farmland and promoting agricultural water-saving.Therefore,accurate measurement of the effective utilization coefficient of farmland irrigation water is helpful to the intensive and economical utilization of water resources and to improve the efficiency of agricultural water use.However,at present,Chinese agricultural metering facilities are insufficient,and basic data collection is difficult.Many factors lead to the low measurement accuracy of effective utilization coefficient for farmland irrigation water,and the expansion of time and space scale is restricted.Therefore,adopting modern technical means and calculation methods to avoid and solve the problems existing in the calculation process of the traditional effective utilization coefficient of farmland irrigation water,so as to accurately and efficiently calculate the effective utilization coefficient of farmland irrigation water,can provide technical support for scientific and rational water distribution in agriculture and strengthen water resources management.In this paper,the typical irrigated area in the upper reaches of the Yellow River-Hetao Irrigation area is taken as the research area.The evapotranspiration of the irrigated area is retrieved based on multi-source remote sensing data and the accuracy analysis is carried out.The supervised classification method is adopted to interpret the land use type of the irrigated area.In order to provide scientific basis for optimizing water resources utilization mode and structure in irrigated areas and promoting agricultural water saving in irrigated areas.The research content and main achievements of this paper are as follows:(1)Based on Landsat remote sensing data,SEBAL model was used to estimate the surface parameters and radiation flux of crop growth and development period from April to October in 2020 in Hetao Irrigation area,as follows: Vegetation coverage,surface temperature,and surface albedo were used to obtain the instantaneous evapotranspiration of Hetao Irrigated area.The sinusoidal curve method was used to expand the temporal scale of the instantaneous evapotranspiration.On this basis,the spatio-temporal variation trend of the evapotranspiration of Hetao Irrigation area was analyzed.(2)Based on MODIS 16A2 remote sensing data,the MRT tool was used to preprocess the data,and the invalid value processing,clipping and mapping of remote sensing data were carried out in Arc GIS software.The typical monthly cumulative 8d evapotranspiration was analyzed,and the spatio-temporal variation characteristics of evapotranspiration in Hetao Irrigation area were verified.Based on the evapotranspiration results obtained by inversion of the above two kinds of remote sensing data,the accuracy of remote sensing inversion results was analyzed by using actual evapotranspiration data of weather stations and crop evapotranspiration data.The results show that the accuracy of evapotranspiration retrieval based on Landsat remote sensing data in Hetao Irrigation area is obviously higher than that of MODIS 16A2.(3)The supervised classification method was used to interpret the land use types of Hetao irrigated area.According to the actual land use of Hetao irrigated area,the land use types of Hetao Irrigation area were divided into five categories,namely forest and grass land,cultivated land,water area,building land and other land,and the accuracy was analyzed by using confusion matrix method.The results showed that the overall accuracy of land use classification results in this study reached 89%,and the Kappa coefficient was 0.8531,meeting the classification accuracy requirements.Combined with evapotranspiration inversion results of Hetao Irrigation area and precipitation and water diversion data of the irrigated area,the precipitation and evapotranspiration of cultivated land use types were calculated,and then the effective utilization coefficient of farmland irrigation water in Hetao Irrigation area was calculated,and the irrigation level of Hetao Irrigation area was scientifically evaluated by comparing and analyzing with the research results of other scholars.It enriches the calculation method of effective utilization coefficient of farmland irrigation water.