Crop Irrigation Water Demand In The Yellow River Basin Under Climate Change Conditions

Affected by global climate change,the extreme weather events occur frequently,resulting in the safe of water resources suffered a great challenge,especially agricultural irrigation.Therefore,studying the crop irrigation water demand under climate change conditions will play an important role in ensuring food security and developing regional agricultural water resource planning.In this study,the main food crops in the Yellow River as the main object.A water balance irrigation model based on the double crop coefficient method was constructed.It was used for calculating the crop irrigation water demand in th,e historical period of the Yellow River and analyzing the sensitivity of crop irrigation water demand.Delta downscale method were used to predict the meteorological factors of the Yellow River and study the irrigation water demand under climate change conditions.The main research content and results of this paper are summarized as follows:(1)A water balance irrigation model based on the double crop coefficient method was constructed in order to simulate the crop irrigation water demand at the main sites in different cropping areas of the Yellow River Basin.The simulated values were different from the studied values.Using the trial and error method to control the |Re| within 10%,the model has good applicability in the Yellow River Basin.(2)The rated irrigation model was used to calculate the irrigation water demand of different crops in the historical period of the Yellow River.The results showed that:the irrigation water demand of winter wheat decreased significantly and the spatial variation of irrigation water was decreasing from the north to the south.The irrigation water demand of spring wheat decreased and the spatial variation decreased from northeast to southwest.The irrigation water demand of spring corn was not obvious and the spatial variation decreased from southeast to northwest.The irrigation water demand of summer corn decreased indistinctively and the spatial variation decreased from west to east.The irrigation water demand of summer corn was small.(3)The sensitivity of crop irrigation water demand to meteorological factors was explored by using the sensitivity coefficient method and constructing a combination of various meteorological factors.The crop irrigation water demand for typical irrigation years was inverse proportion to the precipitation and in proportion to the potential evaporation,the crop irrigation water demand was more sensitive to potential evaporation.When the precipitation and potential evaporation varied homogeneously and changed together,the sensitivity of different crop irrigation water demand were different in irrigation years,and the irrigation water demand of summer corn was more sensitive to changes in precipitation and potential evaporation.In terms of solar radiation,average wind speed and actual water vapor pressure,the sensitivities of irrigation water demand to the meteorological factors:actual water vapor pressure>average wind speed>solar radiation.Summer wheat irrigation water demand was more sensitive to actual water pressure and average wind speed.Spring wheat was more sensitive to solar radiation(4)Combined with the future climate scenarios of the Global Climate Models,Delta downscaling method was used to predict the precipitation,maximum temperature and minimum temperature of the Yellow River.The results show that:In the future,the precipitation in the Yellow River decreased slowly and the mutation time was 2018 and 2030,the minimum temperature increased indistinctively and the mutation time was 2046,the maximum temperature decreased and the mutation time was 2053.The precipitation and temperature had a cyclical variation of 20?30a.In the spatial variation,both precipitation and temperature had strong spatial autocorrelation.Compared with the reference period(1966-2010),the precipitation and temperature increased in the future(5)Future climate scenarios were input to the irrigation model in order to calculate the future crop irrigation water demand in the Yellow River Basin and explore the changes of crop irrigation water demand under climate change conditions.Compared with the historical period,the irrigation water demand of each site in the winter wheat,spring wheat,summer corn and spring corn planting areas varied between-25%?27%,-27%?30%,-30%?25% and-51%?34%.