Objective  To ensure the ecological security and high-quality development of the Yellow River Delta, it is necessary to adjust the crop structure, reduce the proportion of agricultural water and leave enough ecological water.

  Methods  Based on the measured meteorological data of the meteorological station from 2006 to 2019, the variation trend of precipitation and temperature in this area was analyzed, and the evapotranspiration of 7 local non-staple crops in each growth stage and the whole growth period was estimated by using Hargreaves Samani method and FAO crop coefficient method. Combined with the calculation of effective precipitation and leaching water demand, the average irrigation water demand in typical dry and humid years was obtained.

  Results  The results showed that the annual precipitation in the Yellow River Delta has no significant change trend, the precipitation in spring, autumn, and winter showed a downward trend, while the precipitation in summer showed an upward trend. The average annual temperature showed an upward trend year by year. The upward trend of average temperature in summer was the most significant, while the changing trend of temperature in winter was not significant. The irrigation water requirements of non-staple crops in the study area were sweet sorghum > medlar > ryegrass > alfalfa > Jerusalem artichoke > Sesbania > millet. In typical dry years, all 7 crops needed supplementary irrigation. In typical wet years, the precipitation for millet, Sesbania, Jerusalem artichoke and alfalfa was surplus, and in average years, the precipitation for millet and Sesbania was surplus.

  Conclusion  The distribution of effective precipitation in each growth stage of crops is uneven. When there is a surplus of total precipitation in the growth period, some growth stages will still be in a state of water deficit. The research results can provide a reference basis for crop planting structure adjustment and irrigation system optimization in this area.