Optimal allocation of agricultural water resources in Yanghe River Basin based on water requirement of agriculture and animal husbandry

Abstract: With the growth of population and the rapid development of social economy, the shortage of water resources and the pollution of water environment in Yanghe River Basin have become increasingly prominent, which leads to the water quality in the assessment section of Yanghe River Basin is difficult to meet the water quality standard. In order to achieve the efficient utilization of water resources and environmental protection, combining with the characteristics of economic development and water resources utilization, an optimal allocation model of agricultural water resources was established with the water quality constraints for Yanghe River Basin. Therefore, under the premise of the water quality of assessment section, the monthly water allocation of different crops and livestock, as well as the crop planting area and the livestock number were optimized to maximize agricultural economic benefit. The paper proposed a method to control water quality by supplying water and reducing pullution simultaneously. Moreover, based on the water water requirement of agriculture and animal husbandry, this paper introduced a method to avoid unbalanced water supply problems and reduce the dimension to improve the solution efficiency. The optimization results showed that the assessment section of the Bridge 8 could be adjusted to meet the water quality standard by increasing the planting area of the vegetables and the tubers with higher benefit, as well as the large livestock number, and decreasing the planting area of oilseeds with severer emission, as well as the small livestock number. Comparing with the actual values in 2014, the agricultural water allocation decreased by 3.38%, and the economic benefit increased by 11.96%. Therefore, the model was verified effectively. Furthermore, the paper analyzed the optimization allocation schemes under different conditions of the low, median and high flow years in 2020. The results showed that, the more water quantity available, the more agricultural water allocation and river recharge correspondingly. In this condition, water allocation of most water users and subzones were also increased, of which Huailai and Xuanhua had larger increments. Besides, the water allocation of crops was larger than that of livestock, and the grains and fruits had larger increments. The increase rate of water users was relative to planting area, while the increase rate of subzones was relative to the crop type and planting area, and water allocation was the comprehensive tradeoff among available water for agriculture, pollution emissions and economic benefits. The proposed model is of great significance for ensuring water quality safety and sustainable development of regional economy in Yanghe River Basin, and has a certain reference value for optimizing allocation of water resources considering water quantity and quality.