Optimization of Planting Structure under the Background of Water-Saving Irrigation in Shiyang River Basin, China

Adjusting the agricultural planting structure is one of the important means to realize agricultural water-saving, especially in arid inland river basin. In this paper, taking Shiyang River Basin as an example, on the basis of determining the crop water production function, a multi-objective optimization model was constructed, which comprehensively considered the maximization of economic benefits, the green water utilization rate and ecological benefits. The optimized planting structure was obtained by using GAMS (General Algebraic Modeling System) model solver. The results showed that: The common features of the three level years after optimization is that the sown area proportion of wheat, tubers, vegetables, fruits and cotton all increased, of which the sown area of fruits increased most by 5.30 x 104 ha. However, the sown area proportion of corn and oil-bearing crops decreased, of which the sown area of corn decreased most by 8.90 x 104 ha. Comparing of three level years, it is found that the impact of climate change on planting structure adjustment was relatively weak. With the decrease of precipitation, it is suggested to slightly decrease the sown area of wheat but slightly increase the sown area of tubers. The optimization results of planting structure were different in different counties. The average contribution rate of planting structure adjustment to total water-saving was 73.32%, indicating that planting structure adjustment was the key to water-saving. The water consumption of the same crop was different in different counties. Oil-bearing crops and vegetables were more suitable for planting in lower reaches, while corn and tubers were more suitable for planting in middle reaches.