协同调控水-农业-生态的干旱区多水源优化配置

干旱区农业发展往往以挤占生态用水和超采地下水为代价，考虑水-农业-生态互馈关系的水资源优化配置有助于平衡利益冲突。该研究以地下水均衡、经济效益和生态用水满足度为调控目标，构建基于水-农业-生态协同调控的多水源优化配置模型，并推求协调发展度计算式，提出了结合NSGA-Ⅱ算法和协调发展度的协同优化算法，分析石羊河流域水、农业和生态之间的权衡和协同关系，确定水-农业-生态协同提升下的水资源配置方案以及适宜的农业和生态用水比例。结果表明，现状条件下，六河子系统的水资源优化配置方案的经济效益可提升1.9%，实现地下水正均衡0.59亿m³；全流域农业和生态用水比例为90%: 10%，渠井用水比为67%: 33%。平水年保障蔡旗来水为3.48亿m³/a时，能够以牺牲中游1.6%的经济效益实现生态用水满足度和地下水均衡量分别较基准情景提升4.8%和18.6%。研究为协同调控复杂的水-农业-生态关系提供了一种有效方法，可为干旱区流域水资源规划与管理提供参考。

Optimal allocation of multiple water sources in arid areas based on water-agriculture-ecology coordinated regulation

Water scarcity, food crisis, and ecological degradation have been the bottlenecks in a considerable percentage of the world under the dual influence of global climate and human activities. Trade-offs between agricultural development and ecological effects are of great importance, especially in arid areas with highly developed agriculture. Water resources can be allocated, according to the mutual feedback relation among water, agriculture, and ecology. The agricultural and ecological water supply can also be optimized in different units. Synergy effects of the system can be expected to compromise the conflicts for the water security, sustainable development, and ecological health. In this study, an optimal allocation model of multi-water resources was constructed in the Shiyang River Basin using water-agriculture-ecology synergistic regulation. The objectives were taken as the groundwater balance, agricultural benefits, and ecological water use. Besides, the coordinated development degree was deduced using collaborative optimization with the NSGA-II algorithm. Trade-off and collaborative relationships were then quantified among water, agriculture, and ecology. The allocation schemes of water resources were finally proposed for the suitable water use proportion between agricultural and ecological under the synergistic promotion of water-agriculture-ecology. The results showed that the net water demand of irrigation was 14.99×10⁸ m³ in the Shiyang River Basin, whereas, the upper and lower water demand of ecological vegetation were 0.91×10⁸ and 3.35×10⁸ m³, respectively. The current balance between the supply and demand of water resources was attributed to the crowding out of ecological water and overexploiting groundwater. The water demand was also exceeded the water supply, in order to fully meet the minimum demand of for ecological water and groundwater. There was a water shortage of 1.44~2.63×10⁸m³/a in the Liuhe subsystem alone. Furthermore, the agricultural benefits, ecological water use, and groundwater balance were 137.53×10⁸ Yuan, 0.60, and 0.59×10⁸ m³, respectively, in the optimal allocation scheme. The agricultural benefits increased by 1.9% than before. The positive balance of groundwater was achieved in 0.59×10⁸m³. The agricultural and ecological water was accounted by for 90% and 10%, respectively, in the whole watershed, while that in canals and wells was 67% and 33%, respectively. The economic benefits of schemes S2 and S4 were reduced by 5.4%, compared with the optimal decision scheme (S0), while the groundwater balance of schemes S1 and S3 was reduced by 92.9% and 95.2%, respectively. Compared with the baseline, there was a 6% reduction in the water diversion from the middle reaches under diverse water and soil resource management, in order to guarantee a water inflow of 3.48×10⁸m³/a from Caiqi. In this case, the agricultural and ecological water consumptions of the Liuhe subsystem were 13.87×10⁸ and 1.62×10⁸m³, respectively, while the groundwater was in a positive equilibrium of 0.70×10⁸m³. When the inflow in Caiqi was 3.48×10⁸m³/a in a normal year, the ecological water use and groundwater were achieved to balance 1.6% of the agricultural benefits in the middle reaches. The ecological water use and the balance of groundwater were elevated by 4.8% and 18.6%, respectively, compared with the baseline. There was a synergistic trade-off between groundwater balance and ecological water in agriculture. The water resources in arid areas can be managed to maintain an appropriate balance among water security, agricultural development, and ecological health. Failure to consider the mutual influence among different water users can result in the decision biases and suboptimal schemes. This finding can provide an effective way to analyze the complex relationship among water, agriculture, and ecology. A strong reference was also offered for water resource planning and management in arid basins.