| China is one of the top ten rice agricultural countries in the world,and the resear ch on rice irrigation water consumption has always been the focus of research in China.According to the principle of controlled irrigation technology and the existing research results,grid data are used to estimate and forecast the rice irrigation water consumption,so as to understand the rules of rice irrigation water and water demand.It lays a foundation for alleviating the contradiction between supply and demand of water resources in irrigation area and making the optimal scheduling scheme of multiple water sources.The main research contents and conclusions are as follows:(1)According to the research results of water-saving controlled irrigation technology for rice in North China,meteorological data and irrigation water data of each typical irriga tion area are collected and analyzed.The soil water regression coefficient method is used to calculate the field irrigation water consumption and the annual average irrigation water consumption in each growth period from 2008 to 2020.The average annual increase rate of field irrigation water consumption from 2008 to 2020 is 1.3 mm/a.The irrigation water used by rice under controlled irrigation condition is calculated by field leakage method,and the accuracy is tested with the measured water used by rice.The correlation coefficient of typical irrigated area is between 0.79～0.92,and RMSE is between 5.88～9.30.It is considered that the deviation between the calculated value and the measured value is small,and the calculated result is good.This method has a good applicability in the calculation of irrigation water consumption of paddy fields in North China.(2)FAO-56 PM method is used to calculate the reference crop efflorescence and rice water demand in typical irrigated areas.The variation trend of reference crop efflorescence and rice water demand is analyzed,and the rice water demand is compared with rice water utilization under controlled irrigation conditions.The inter-annual variation of reference crop evapotranspiration and rice water demand from 2008 to 2020 showed a fluctuating state,with a decreasing trend first and then increasing trend on the whole,but an increasing trend on the whole.Under controlled irrigation,the ratios of average rice water use to rice water demand in typical irriga ted areas for years are 0.79,0.81,0.82,0.79,0.80,0.80,respectively.Compared with normal rice growth,rice evapotranspiration under controlled irrigation decreased by 20% on average,which significantly reduced inter-plant evaporation and field leakage.The water saving effect is very remarkable.(3)Based on the downscaling data of future climate scenarios,the rice water demand and irrigation water consumption under controlled irrigation in typical irrigated areas from 2021 to 2100 are predicted,and the change trend under future climate scenarios is analyzed,and compared with the annual average rice water demand and irrigation water consumption under controlled irrigation from 2008 to 2020 were compared.Under the RCP4.5 scenario,the annual average irrigation water consumption increases by 1.0mm/a from 2021 to 2100.Under the RCP8.5 scenario,the annual average irrigation water consumption will increase by 1.8mm/a from 2021 to 2100.Under the future scenario,the water consumption for controlled irrigation will increase,and the growth rate from2008 to 2020 will exceed the growth rate from 2021 to 2100 under THE RCP4.5 scenario,but not reach the growth rate from 2021 to 2100 under the RCP8.5 scenario.The increase of water consumption for controlled irrigation is bound to further aggravate the contradiction between water supply and demand.In the future,the construction of irrigation and water conservancy projects and supporting facilities should be further improved to optimize water resource scheduling strategies,so as to improve the utilization efficiency of irrigation water. |
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