Optimization Of Grain,Vegetable And Fruit Planting Structure In Hebei Province Under The Constraint Of Water Resources

Crop planting structure is an important factor of agricultural water resources utilization and food safety.Hebei Province,located in the North China Plain,is an important grain producing area in China,but it has the serious contradiction between water and grain,and groundwater overexploitation,which limits the improvement of ecological environment and the development of regional agriculture.Therefore,from the perspective of“determination of yield with water”,the primary crop planting structure in Hebei Province is optimized,which provides support for the utilization of agricultural water and sustainable development in water resources shortage areas.The dietary consumption of Chinese residents is changing from a dual structure of“grain and vegetable”to a diversified type of“grain,meat,vegetable and fruit”.Based on the goal of balanced dietary needs of residents,the study optimizes the cultivation structure of grain,vegetable and fruit crops in Hebei Province under the limited supply of water resources.Taking 2019 as the planning base year,the model of grain,vegetable and fruit crop cultivation structure is constructed with the maximum total production and minimum agricultural water consumption as the objectives,and the total crop cultivation area,agricultural water consumption and food demand as the constraints,and the NSGA II algorithm is used to solve the model.The main conclusions are as follows:（1）The total crop production in Hebei Province continued to rise,with an overall decrease in sown area and an increase in unit production;agricultural water consumption decreased slightly.From 1984 to 2019,the overall crop production of grain,vegetables and fruits in 11 cities in Hebei Province rose,with an average annual growth rate of 7.13%,10.19%and 15.04%,respectively.During the same period,the sown area of grain,vegetables and fruits decreased as a whole,and the unit production increased.2000-2019,the annual average value of total agricultural water consumption in Hebei Province was 14,272.8 million m~3,with an overall decreasing trend and an average annual decreasing rate of 1.88%.（2）Under the constraint of water resources,when the agricultural water consumption is the least,the grain planting area is decreased and the fruit area is increased.Crop yields meet low levels of balanced dietary needs.Compared with 2019,the planting area of grain and vegetable crops decreased by 19.91%and 0.52%,respectively,and the planting area of fruit crops increased by 2.62 times.The production water consumption of Scheme 1 is 101.68 billion m~3,and the water saving is 661million m~3,accounting for 88.96%of the total agricultural water consumption.（3）Under the constraint of water resources,when the agricultural water consumption is the largest,the planting area of vegetables and fruits is reduced,the grain planting area is increased,and the crop yield meets the high level of balanced dietary demand.Compared with 2019,the total planting area increased by 31.37thousand hm~2,the proportion of grain planting area increased by 7.14%,and the proportion of vegetable and fruit planting area decreased by 3.52%and 3.63%,respectively.The total amount of production water in scheme 2 was 11.081 billion m~3,which was 252 million m~3 higher than that in 2019,accounting for 96.95%of the total amount of agricultural water.The results of the multi-objective planting structure optimization model show that in order to achieve a high level of food demand,Hebei Province should reduce the cultivation area of high water-consuming crops such as vegetables for achieving efficient use of water resources and meeting the balanced dietary needs of residents.Among them,Chengde City,Baoding City and Xingtai City should develop forestry and fruit cultivation with the advantage of regional topography to reduce the occupation of arable land;plain areas such as Cangzhou City and Hengshui City should ensure efficient utilization of arable land and high grain yield to further improve arable land production capacity.In addition,there is space to improve the agricultural water use efficiency and water saving potential of each city in Hebei Province,and modern water saving technologies such as micro-irrigation and drip irrigation should be vigorously developed to maximize the efficient use of water resources.