Trend of agricultural plantation and irrigation requirements in the upper reaches of Xiong'an New Area

The agriculture is a major consumer of water. Since Xiong'an New Area is facing serious water shortage and groundwater declining, it is necessary to optimize the scale of upstream agriculture water use. By using crop models for simulating the irrigation requirements of wheat and maize, and taking the Pan-evaporation coefficient (K_p) approach to estimate the irrigation requirement of other crops, such as vegetables and fruit trees, our study reconstructed the spatial and temporal trend of agriculture plantation and irrigation requirement in the upper reaches of Xiong'an New Area from 1970. The proportion of irrigation requirements and time-dependent changes of different crops formed a clear trend. The results showed that the total planting area generally increased. There was no significant change in the area of cultivated land and the effective irrigated area. The average cultivated area for many years was 849 000 hm², while the effective irrigated area averaged 713 000 hm², accounting for 84% of the total cultivated land area. The planting area of wheat decreased slightly, the planting areas of maize and vegetables increased significantly, and the planting proportion of fruit trees increased in the mountain area and decreased in the plain area. The annual average irrigation requirement was 22.52×10⁸ m³, of which wheat, maize, vegetables, fruit trees, and other crops accounted for 58.6%, 12.6%, 5.8%, 16.3%, and 6.7% of the total irrigation requirement, respectively. The irrigation requirement of vegetables and fruit trees increased significantly, and was affected by the increase in planting area. Spatially, the total irrigation requirement increased significantly in the mountain area but decreased in the plain area. After elimination of the influence of annual precipitation fluctuation, the irrigation requirement showed a sharply increasing trend from 1970 to 2015, but slowed down in the mid-1980s. Owing to the increase of planting area and irrigation requirements of vegetables and fruit trees, the irrigation requirement showed a slow increasing tendency overall. Therefore, controlling the agricultural water use in the upper mountainous reaches of Xiong'an New Area, planting of low-water-consuming crops and reducing the planting area of water-consuming crops are keys to restoring water production for Xiong'an New Area. Finally, the sustainable utilization of regional water resources should be based on local natural conditions and the layout of agricultural production should be arranged in accordance with the spatial and temporal distribution of water resources to seek a coordinated development for the water-ecology-social economy of Xiong'an New Area.