| Ningxia is located in the northwest of China,is arid and semi-arid climate,is one of the most scarce areas in China.In recent decades,due to the influence of social and economic development and local policies,the agricultural planting structure in Ningxia has undergone great changes,which directly affects the agricultural water demand of the whole region.Therefore,deeply studying the evolution of agricultural planting structure and its impact on agricultural water demand has an important reference value for the efficient utilization of water resources and the high-quality regional development.On the basis of extensive data collection,this paper uses multivariate statistical analysis,Mann-Kendall test,ArcGIS spatial analysis and multi-objective optimization model to reveal the spatial and temporal evolution law of agricultural planting structure,and obtains the adjustment plan of agricultural planting structure in Ningxia.The main conclusions are as follows:(1)Based on the meteorological and agricultural data in Ningxia,using the peng man formula method and irrigation quota method calculated the Ningxia rice,wheat and corn net irrigation water demand,the results show that the two methods of wheat and corn net irrigation water demand fit is high,quota method of rice net irrigation water demand is greater than peng man formula calculation of rice net irrigation water demand.The influencing factor of agricultural water demand was analyzed by gray correlation method,principal component analysis method and ridge regression method,and it found that planting area is the dominant factor of agricultural water demand.(2)The changes of crop planting area and planting structure in Ningxia were analyzed by using multiple statistical analysis and Mann-Kendall test.The results showed that the planting area of wheat,beans and oil decreased significantly,the food crop area decreased but not significantly,and the area of other crops increased significantly.From 1993 to 2019,there were 28 planting structure types in Ningxia,which continued to increase and reduced the type of single planting structure continuously,gradually transforming into a variety of crop combination planting structure,and the planting structure was more diversified.(3)The ArcGIS software spatial analysis tool was applied to analyze the spatial change of the planting structure of various crops in Ningxia.The results showed that rice planting was mainly concentrated in the northern Yellow River irrigation area,and the rice planting area in all counties increased to varying degrees.Wheat,corn,vegetables and fruits were all planted in 22 counties and districts in Ningxia.The planting area of wheat was decreasing,while the planting area of corn,vegetables and fruits was on the rise.From 1 993 to 2019,the planting structure in the northern irrigation area was mainly corn,rice,vegetables and fruits;in the central arid zone,from single wheat to wheat,and in the southern mountainous area,wheat to corn,potato and wheat.(4)With the goal of improving agricultural economic benefits and reducing agricultural water demand,the planting structure optimization model was established,and the STEM method was used to solve the optimization scheme of crop planting structure in Ningxia was obtained.The results show that scheme 2 is the optimal scheme,and the water demand decreases by 286 million m3 compared with that before the adjustment,and the net output value increases by 3.519 billion yuan.The optimized scheme saves water resources and obtains higher economic benefits. |
PDF Full Text Request