灌区节水的生态环境效应及高效用水调控

In arid and semi-arid irrigation districts, various water-saving strategies and practices have been found of impacts on the local as well as regional hydrological, ecological and environmental processes. The objectives of this proposal are to assess the effects of various water-saving practices on ecological and environmental situations both on farmland and irrigation district, and to understand the mechanisms of improving water productivities under different scales, and propose appropriate water-saving practices considering the sustainable agriculture and eco-environment. Agro-hydrology models will be developed to quantitatively characterize the relationship among the hydrological components, crop growth, and yield as well as water productivity. Response of hydrological processes and water productivity to various water saving practices will analyzed under different scales. The effects of various water-saving practices on ecology and environment will be quantitatively assessed accordingly. Considering the impact of water saving practices on water productivity and eco-environment, scenarios analysis will be carried out, and water saving thresholds will be proposed both for farmland and irrigation district. Based on the multi-objective analysis and various optimization methodologies, agricultural water management strategies and program will be developed. The proposed research results are expected to provide scientific implications for the efficient use of irrigation water and the protection of ecology and environment in arid and semi-arid irrigation districts.

灌区高效用水及生态环境效应是旱区农业可持续发展的重要因素，其涉及水转化及物质迁移转化、作物生长及生态植被响应的生物过程，且各过程相互作用耦合。本项目拟开展农业节水条件下灌区多尺度水文过程与生态环境响应及农业水生产力提升的适应性调控研究，通过农业水文－生态环境－农业水生产力多过程和多尺度监测、数学模型、情景分析等方法，围绕灌区农业节水对生态环境及水生产力驱动机制、量化表征及适应性调控方面开展研究，阐明农业水转化过程与物质迁移转化规律，揭示农业节水对多尺度水文及生态环境与水生产力的驱动机制；建立农业水文及伴生多过程耦合与农业水分生产力的定量表征模型与方法，探讨灌区农业水生产力的尺度效应和提升机制；发展农业节水的生态环境效应的评估方法，实现灌区生态环境演变的认识由定性向定量方向发展；提出节水、控盐、提效等多目标的灌区农业节水阈值与调控模式，为灌区农业高效用水与生态环境保护提供科学依据与定量方法。

本项目围绕我国北方干旱灌区灌排不合理导致水肥利用效率低、土壤次生盐渍化严重、农业面源污染突出等问题，以内蒙古河套灌区为典型研究区，系统开展了节水条件下灌区多尺度农业水转化与伴生多过程耦合及量化表征、灌区的生态环境与水生产力对节水响应、灌区农业高效用水的适应性调控等研究。主要的研究内容和取得的成果如下：（1）开展了不同灌溉条件下农田水热通量、多尺度水-盐-氮多过程的定位试验和区域监测，揭示了农田水盐运移响应规律及其与作物生长的互馈作用、地下水系统对农田耗水的贡献机制；发展了农田尺度水-盐-氮耦合模拟模型，建立了适用于干旱地下水浅埋灌区（流域）农业水文模型，量化了干旱灌区多尺度农业水转化及其伴生多过程，明晰了灌区水-盐-氮耦合机制及其对农业节水的响应机制；（2）量化了干旱区树木蒸腾变化规律及其对地下水系统的依赖关系，确定了树木耗水的地下水埋深阈值；集成采样试验、地统计方法与水盐运移均衡模型，解析了研究区水盐时空动态特征与盐分累积规律及其归趋平衡机制；明晰了灌区主要大田作物小麦-玉米-葵花农田系统水-碳-氮循环转化过程，揭示了农田温室气体排放和农业面源污染形成机制及其对农业节水的响应规律与面源污染削减机制；（3）明晰了不同节水处理条件下作物水生产力变化特征，建立了多尺度水转化要素与农业水生产力的定量关系与模拟模型，揭示了灌区多尺度水生产力提升机制；（4）构建了基于水文过程的多种作物间的模拟-优化灌溉调控模型、基于农业水文过程的多层多目标区域灌溉决策优化模型，实现了灌区农业种植结构调整、灌溉定额控制、渠系衬砌、优化配水等多维决策，提出了基于水转化多环节调控的多维协同节水综合调控模式与农业节水阈值。项目成果在国内外学术刊物上发表论文78篇，申请（授权）发明专利3件、获软件著作权6项，培养长江学者1位、杰青1位、优青2位、教授3位、博士16人、硕士13人，获教育部自然科学二等奖1项。