| In order to quantify the water demand and water deficit indices of drought-alkali wheat in Hebei Province at each growth stage, using the meteorological observation data of the main production areas of drought-alkali wheat, the Pearson Ⅲ type curve was used to determine the four hydrological annual types of wet year, average year, dry year and extreme dry year and the corresponding effective precipitation. Characteristics of water deficit and irrigation demand index and their spatial and temporal distribution characteristics were determined using the Penman-Monteith model, combined with the crop coefficient method and the soil correction coefficient method. The results showed that from 1988 to 2022, the water demand of drought-alkali wheat increased significantly during the whole growth period, and the precipitation, effective precipitation, and water deficit showed an increasing trend. The water deficit and irrigation demand indices increased significantly with the decrease of annual precipitation. For the four hydrological annual types, the water deficit were 97.7, 106.5, 126.2 and 149.7 mm, respectively; the irrigation demand indices were 0.56, 0.60, 0.70 and 0.79, respectively, while the difference in water demand was 181.0 mm among different year patterns. Spatially, the water demand was more in the north and less in the south, and the water deficit was more in the northwest and less in the southeast. There were obvious differences in the characteristics of water demand at different growth stages, and the water demand from the reviving stage to the grain filling stage was larger, and the water deficit was more serious. The deficit was the most serious at the reviving stage, with the water demand, water deficit and irrigation demand indices were 48.1 mm, 38.7 mm, and 0.80, respectively. As a whole, the irrigation of drought-alkali wheat can be carried out according to the hydrological year with different proportions, which can save irrigation costs and ensure the stable and high yield of drought-alkali wheat. Expansion to Mengcun, Yanshan, and Haixing counties and cities in the south can effectively expand the sowing area of drought-alkali wheat and strengthen the comprehensive utilization of saline-alkali land. |
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